Preface

Tomatoes are one of the most valuable and popular vegetables worldwide. The fruit of each cultivar differs in size, shape, taste, and color, as well as the firmness of skin and flesh. Ideally, tomatoes should be fertile and disease resistant. With increased consumer demand for large salad-type tomato varieties, they also need to be robust to meet transportation conditions. More than 80% of tomatoes grown worldwide are processed into products such as tomato juice, paste, puree, ketchup, sauce, and salsa.

Tomatoes and tomato-based food products are rich in biologically active compounds such as polyphenols and carotenoids (mainly lycopene), which have numerous biological functions in the human body. Rising market demand has stimulated the development of diverse production methods for these compounds, and nowadays, lycopene is mainly produced through chemical synthesis. Nevertheless, bioactive compounds of natural origin enjoy both higher bioaccessibility and greater consumer trust. The industrial processing of tomatoes into tomato products generates large amounts of by-products (peel, pulp and seeds). These by-products are costly to dispose of and have a potentially negative impact on the environment, but they also represent a promising, low-cost source of carotenoids (primarily lycopene).

Among the interesting research topics covered in this book are the chemical composition, nutrition, production, and protection of tomato plants, and tomato processing applications, including sustainable technologies. This book will be of significant value to researchers, academics, and students in the field of agronomy, food, pharmacy, and other sectors.

> **Pranas Viškelis, Jonas Viškelis and Dalia Urbonavičienė** Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Babtai, Lithuania

**1**

Section 1

Tomato Plant Nutrition

and Production

Section 1

## Tomato Plant Nutrition and Production

#### **Chapter 1**

## Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown under Salt Stress

*Salma Wasti, Salwa Mouelhi, Feriel Ben Aïch, Hajer Mimouni, Salima Chaabani and Hela Ben Ahmed*

#### **Abstract**

Abiotic environmental stresses such as drought stress, mineral deficiency, heat stress, and salinity stress are major limiting factors of plant growth and productivity. Tomato (*Solanum lycopersicum* L*.*), one of the important and widespread crops in the world, is sensitive to moderate levels of salt in the soil. So many authors have reported large variation among tomato genotypes in their response to salinity. The present study was conducted to study the effect of different concentrations of salicylic acid on growth parameters, yield, and yield attributes of tomato under saline conditions. Tomato plants cv. Marmande were grown under normal or saline (100 mM NaCl) conditions. Different levels of salicylic acid: SA (0, 0.01, 0.1, and 1 mM) were applied as a foliar spray. The study was conducted at the vegetative and reproductive stage. Salt stress reduced significantly the whole plant growth at the two stages. Application of SA caused a significantly increase in biomass under non-saline conditions. However, in salt medium, treatment of leaves by SA induces a slight increase in biomass, leaf area and ameliorates the fruit diameter compared with plant grown only in the presence of salt. The beneficial effect of SA is more pronounced with the dose 0.01 mM.

**Keywords:** tomato, growth, foliar spray, fruit, salinity, salicylic acid

#### **1. Introduction**

During their development cycle, plants are exposed to several constraints under inappropriate environments without being able to escape them. Soil salinity is a major abiotic factor that reduced productivity of many crops.

About one third of the irrigated land in the world is affected by salinity to varying degrees [1]. According to FAO [2], more than 800 million hectares of land around the world are affected by salinity, accounting for more than 6% of the earth's surface. In Tunisia, saline soils cover about 23% of the total area, i.e., 8.7 million hectares of

arable land [2]. It caused various deleterious effects on morphological, physiological, biochemical, and nutritional attributes. During the onset and development of salt stress within the plant, all mechanism such as: photosynthesis and protein synthesis are affected. So, plants' first reaction was to reduce the extension of leaf area, followed by extension cessation with the increase of stress [3].

Tomatoes (*Solanum lycopersicum* L.) are today the most consumed vegetable in the world. They are an important greenhouse crop in semiarid coastal areas of Mediterranean countries. In these regions, soil and groundwater salinity are insidious problems that affect both tomato yield and quality [4]. It is known that dry biomass and fruit yield of tomato plants are strongly affected by soil salinity [5]. In a recent study, Ors and al. [6] reported that photosynthetic rate, plant dry weight, stomatal conductance, chlorophyll reading value decreased with salt in tomato seedlings. Plants exposed to NaCl stress were confronted with three fundamental problems, which are reduction of water potential, ion toxicity associated with the excessive accumulation of sodium (Na+ ) and chloride (Cl−) leading to essential cations potassium (K<sup>+</sup> ) and calcium (Ca2+) deficiency, and production of ROS [7]. Salinity causes also unfavorable conditions that limit normal plant production. The increase of salinity most often causes a decrease in plants development and in general the average weight, the diameter of the stems, and size of the fruits were reduced significantly. Thus, driving with high salinity results in, therefore, a loss of production [8].

Furthermore, many research studies have focused on the physiological responses of plant subjected to salinity. The development of plants tolerant to environmental stress is seen as a promising approach, which can help satisfy the growing food demands in the world. Thus, overcoming NaCl stress is a major objective to ensure the stability of agricultural production. Salicylic acid (SA) is a signaling molecule that plays an important role in the induction of acquired systemic resistance (ASR) against pathogens; it was first demonstrated to play a crucial role in biotic stress such virus, fungi, [9]. Progressively, it was shown that SA induces tolerance to major abiotic stresses such as drought and salinity. Most papers, on this subject, have reported on the protective effect of exogenous salicylic acid against abiotic stress [9]. The exogenous application of SA affects various physiological, biochemical, and molecular processes in plants. Gharbi and al. [10] reported that SA (0.01 mM) enhanced shoot growth in Solanum lycopersicum cv Ailsa Craig and its wild salt-resistant relative Solanum chilense. Moreover, Mimouni and al. [11] found that the application of SA (0.01 mM) restored photosynthetic rates and photosynthetic pigment levels under salt (NaCl) exposure.

The purpose of this work was to study the effect of different concentrations of salicylic acid on growth parameters; yield and yield attributes of tomato under saline conditions. The study was conducted at two stages (vegetative and reproductive) and based on growth parameters (biomass production and leaf area).

#### **2. Materials and methods**

#### **2.1 Plant material and growth conditions**

Plant material studied is the cultivated tomato (*Solanum lycopersicum* L.) *var* Marmande. The tomato seeds were germinated in Petri dishes. Boxes containing 20 seeds are placed in an enclosure air-conditioned at a constant temperature (25°C) and under an illumination at low intensity (10 μ mol m−2 s−1). Eight days after, seedlings were transferred to nutrient solution composed by macroelements and microelements *Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown… DOI: http://dx.doi.org/10.5772/intechopen.106769*

as described by Wasti and al. [12] and placed in a *growth chamber* under controlled environmental conditions with relative humidity of 80%, temperature 25/18°C (day/ night), artificial light 150 μmol.m−2. s−1, and 16 h photoperiod. Two experiments were undertaken: one at the vegetative stage and the other at reproductive stage. The salicylic acid was applied as a foliar spray.

#### **2.2 Experience 1**

The plants were grown in pots, each pot containing four plants. The plants were grown for 11 days before the start of salt treatment. Each pot receives a basic nutrient solution. After an acclimation period of 11 days, the seedlings at three-leaf stage are divided into eight lots. Four control groups without NaCl continued to grow in the basic nutrient solution : Lot (1), the leaves are sprayed daily until the end of culture by distilled water, while the lots (2), (3), and (4) are sprayed with distilled water supplemented with SA (0.01, 0.1, 1 mM). The other four lots are transferred to nutrient solution enriched with NaCl (100 mM), and the leaves are sprayed daily until the end of the culture by distilled water added or not by salicylic acid (0.01, 0.1, 1 mM). The addition of salt is done gradually, with 25 mM every 24 hours, until a final concentration of 100 mM. The pH was adjusted to 5.9 with KOH (1N).

#### **2.3 Experience 2**

The second experiment was conducted under the same culture conditions as above, has tracked the growth and development of plants to produce fruit. The plants were divided into four groups. Two groups continued to grow on the nutrient solution, leaves of the first group were sprayed with distilled water while those of the second batch were sprayed with a solution of 0.01 mM SA. Plants of the third and fourth groups were transferred to a nutrient solution supplemented with 100 mM NaCl and leaves were sprayed with SA solution 0.01 mM. Spraying of SA continued until flowers were developed.

#### **2.4 Growth parameters and ion analysis**

\* Dry mass (DM) was determined after desiccation at 80°C for 48h. \* Sensitivity index (SI), i.e., the difference between dry matter production of treated plants and the control, expressed in percent of the latter, was calculated according to the following expression:

$$\text{SI}\_{\text{treatment}} = \left(\mathbf{100} \,\mathrm{x} \left(\mathrm{DM}\_{\text{treatment}} - \mathrm{DM}\_{\text{control}}\right) / \mathrm{DM}\_{\text{control}}\right). \tag{1}$$

This parameter was more negative when the plant was sensitive to treatment \* *Leaf area* of the tagged leaf 5 was determined by using a leaf area meter AM 300.

#### **3. Results**

#### **3.1 Plant growth**

The tomato seedlings treated with 100 mM NaCl are less developed than the control plants. Indeed, salt stress reduced significantly the whole plant growth (42% compared with control). Application of SA caused a significantly increase in biomass of whole plant under non-saline conditions. This increase is about 45, 30, and 32% (compared with control plants sprayed with distilled water) respectively for the concentrations 0.01, 0.1, and 1 mM. (**Figure 1**). This beneficial effect is more pronounced at the root system where there is a significant increase in biomass, about 66, 52, and 57% respectively, compared with control for the doses (0.01, 0.1, and 1 mM), whereas in aerial organs, stimulation is about 52, 33, and 32% for leaves and 26, 19, and 25% for stems compared with the control respectively for doses (0.01, 0.1, and 1 mM). (**Figure 2**).

Salt negatively affects the three organs. However, the roots were much less sensitive to NaCl than the aerial parts (leaves and stems). The decrease in dry matter was respectively 16, 40, and 50% (**Figure 2**). Foliar application of SA reduced the damaging effect of salinity on plant. The masses of dry matter increased compared with plants subjected only to NaCl. Indeed, in the presence of NaCl 100 mM, inhibition of growth of the whole plant was about 42% compared with the control plants, it was 40% when plants treated by salt were sprayed with Sa 1 mM and the inhibition was even more attenuated (29 and 27%) with the lower doses of SA (0.1 and 0.01 mM) (**Figure 1**). The root system of plants subjected to salt and sprayed by 0.01 mM SA was stimulated by 4% compared with the control (**Figure 2**).

#### **3.2 Leaf area**

The salt induced a decrease in leaf area by 50% in leaves of rank 5. Foliar application of SA induced an increase in leaf area of stressed plants. The stimulation was significantly with SA application at 0.01 and 0.1 mM (**Table 1**). While the foliar spray of SA did not affect the expansion of leaf plants grown without NaCl.

#### **3.3 Na+ compartmentalization**

Vacuolar compartmentalization of Na+ ions is one of the major strategies for salt stress tolerance. In tomato *var*. Marmande, when the content of Na+ ions increases,

#### **Figure 1.**

*Dry mass of the whole plant of tomato var Marmande submitted to 100 mM NaCl for 18 days and sprayed or not with salicylic acid (1; 0.1; 0.01 mM). Data are means of 16 replicates ± SE. Means with similar letters are not different at P* ≤ *0.05 according to Duncan's multiple range test at 95%.*

*Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown… DOI: http://dx.doi.org/10.5772/intechopen.106769*

#### **Figure 2.**

*Dry mass of leaves, stems, and roots of tomato seedlings submitted to 100 mM NaCl for 18 days and sprayed or not with salicylic acid (1;0.1; 0.01 mM). Data are means of 16 replicates ± SE. Means with similar letters are not different at P* ≤ *0.05 according to Duncan's multiple range test at 95%.*

a drop in the water content of leaf tissue is observed (**Figure 3**); this decrease suggests that Na+ is not properly compartmentalized in the leaf tissue vacuole; on the contrary, it is accumulated in the extracellular spaces. This accumulation is associated with a tissue dehydration. In the presence of NaCl, foliar spray of salicylic acid with


**Table 1.**

*Leaf area (cm2 ) of order 5 of tomato seedlings submitted to 100 mM NaCl for 18 days and sprayed or not with salicylic acid (1; 0.1; 0.01 mM). Data are means of 16 replicates ± SE.*

#### **Figure 3.**

*Dry mass of leaves of tomato seedlings cultivated to the reproductive growth stage in the absence (Control) or presence of NaCl 100 mM and sprayed or not with salicylic acid 0,01 mM. Data are means of 16 replicates per treatment. Means with similar letters are not different at P < 0.05 according to Duncan's multiple range test at 95%).*

different concentrations (1, 0.1, and 0.01mM) improves vacuolar Na<sup>+</sup> compartmentalization, as shown in **Figure 3**, since leaf water contents are relatively stable, despite the accumulation of leaf with sodium. Maintaining leaf tissue hydration despite the accumulation of sodium suggests that the leaves have a light ability to compartmentalize Na<sup>+</sup> in the vacuoles.

#### **3.4 Reproductive growth stage**

Based on the results of the first experiment, the better amelioration of salt tolerance of tomato plants was obtained with SA 0.01 mM, for this we have used the dose (0.01 mM) in this part of our study. Salt stress at the reproductive stage caused

*Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown… DOI: http://dx.doi.org/10.5772/intechopen.106769*


*Data are means of 16 replicates per treatment. Means with similar letters are not different at P < 0.05 according to Duncan's multiple range test at 95%.*

#### **Table 2.**

*Yiedl parameters of tomato seedlings cultivated to the reproductive growth stage in the absence (Control) or presence of NaCl 100 mM and sprayed or not with salicylic acid 0.01 mM.*

**Figure 4.**

*Relationship between sodium and water in the leaves of tomato seedlings submitted to 100 mM NaCl for 18 days and sprayed or not with salicylic acid (1; 0.1; 0.01 mM). Data are means of 16 replicates.*

a reduction in plant size, number of stalk, and fruit diameter. In detail, the length of the plants decreased from 170 cm to 75 cm, so compared with control, reduction was about 56%. In control medium, plants sprayed or not by SA at the stage were at 25 foliar stages. In the presence of 100 mM NaCl, they only have 17 stages and thus have a developmental delay. In addition, there was a significant decrease in the number and the size of fruit; it is respectively about 70 and 67% compared with control (**Table 2**).

The salt has a depressive effect on weight of aerial organs in particular stems. The decrease was equal to 70%. The foliar spray of salicylic acid (0.01 mM) attenuated the effect of salt. The reduction was more than 30% (**Figure 4**). The fruit diameter was enhanced. The amelioration was about 16% compared with plants subjected only to NaCl.

#### **4. Discussion**

Saline soils and saline irrigations constitute a serious production problem for vegetable crops as saline conditions are known to suppress plant growth [13]. The present study demonstrates salinity adversely affected the growth of tomato *cv* Marmande regardless of SA treatments. Earlier studies have shown that the concentration of 100 mM NaCl decreased total dry biomass and leaf area [11, 14]. Also, previous study reported a decrease in whole plant DW, shoot DW, root DW, and leaf area in tomato plant *cv*. Marmande under NaCl stress [11]. In fact, the reason of this reduction is due essentially to the nutritional imbalance and the specific ion toxicity [15]. On the other hand, it could be due to the decrease of the water content in relation to a decrease of external water potential [16]. However, foliar SA applications reduced the negative impact of salinity on growth of tomato plants. Application of SA caused a significantly increase in biomass under non-saline condition. Spraying leaves with SA at concentrations (0.01, 0.1, and 1 mM) in tomato seedlings grown on medium supplemented with 100 mM NaCl improves their tolerance to salinity, this increased tolerance is evidenced by the increase mass of dry matter and leaf area compared with plants that are subjected only to NaCl (**Figures 1** and **4**).Various studies on different plants, including quinoa [17], barley [18], and cowpea [19], showed that the use of SA ameliorates growth biomass under NaCl stress. Foliar applications of SA (0.01, 0.1, and 1 mM) in tomato seedlings grown on control medium induced a strong increase in biomass production at the whole plant, it is about 45, 30, and 32% respectively compared with the control for concentrations 0.01, 0.1, and 1 mM. These results are in agreement with those of El-Tayeb [8] and Arfan et al. [9], who reported that exogenous foliar application of SA ameliorated the adverse effects of salt stress on growth of barley and cowpea. Similarly the work of Noreen et al. [10] shows that exogenous application of SA stimulates foliar growth in sunflower plants grown in the absence or in the presence of salt. Similar results were obtained by Idrees et al. [11]. Also, Abdi et al. [12] showed that the salicylic acid causes a significant increase on the plant density and dry weight of root and shoot. Spraying maize plants "Single hybrid 10" with SA increased dry weight of stem, leaves, and whole plant [12].

To better assess the effect of salt and salicylic acid on growth of tomato seedlings *cv* Marmande, we have calculated a sensitivity index (SI) based on the dry matter production. **Table 3** shows that the presence of NaCl affects the three organs; however, it is the aerial organs, especially stems, that reflecting the greater depressive effect of salt. Foliar spraying of SA (0.01, 0.1, and 1 mM) reduces the effects caused by NaCl, this beneficial effect is more pronounced with the dose 0.01 mM, the improvement was about 15% compared with plants subjected only to NaCl. The protective effect of


#### **Table 3.**

 *Index of salt sensitivity of roots, stems, leaves, and whole plant of Marmande tomatoes submitted to 100 mM NaCl for 18 days and sprayed or not with salicylic acid (1; 0.1; 0.01 mM).*

*Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown… DOI: http://dx.doi.org/10.5772/intechopen.106769*

exogenous salicylic on plants cultivated under abiotic stress have been also reported by Idrees et al. [21] on in lemongrass plants subjected to water stress and by Abdi et al. [22] on Marigold cultived under salt stress.

Most commercial tomato cultivars are moderately sensitive to salinity at all stages of development, including seed germination, vegetative growth, and reproduction, and therefore yield is markedly reduced [23].

Our study reports that during the whole development cycle, tomato was sensitive to NaCl. Dry weight of the leaves decreased significantly (−70%). Salt affected negatively yield and yield attributes of tomato (plant size, number of stalk, number, and size of fruit). Decreased shoot and root weight, plant height, and leaf number were reported in soybean plant due to salt stress [24]. Also Lauchli and Grattan [25] reported that salinity adversely affected performances of grain crops and cowpea plants at flowering and seed filling stage. Kinsou et al. [26] also report that salinity reduced the number of fruits in tomato (*Lycopersicon esculentum* Mill.) *var* Akikon. This number has increased from approximately 7.67 in the control plants to 5 fruits at 30 mM NaCl. Salt stress reduces also the size of tomato fruits, the productivity and increases flowering time. Foliar spray of salicylic acid (0.01 mM) counteracted salt-stress-induced growth inhibition and improved yield attributes of tomato. The fruit diameter was enhanced, amelioration was about 16% compared with plants subjected only to NaCl. According to Shakirova et al. [27], the positive effect of salicylic acid on growth and yield can be due to its influence on other plant hormones. Salicylic acid altered the auxin, cytokinin, and ABA balances in wheat and increased the growth and yield under both normal and saline conditions. Stimulation of yield under foliar application of salicylic acid could be assigned to the well-known roles of these plant hormones on photosynthetic parameters and plant water relations. Some studies showed that SA increased membrane permeability facilitating absorption and utilization of nutrients [28]. This would contribute to ameliorating the growth of the stressed plants.

In conclusion, from the results of this study, it can be affirmed that exogenous application of SA (0.1 mM) as foliar spraying once at vegetative and second time at reproductive stage influences growth parameters; yield and yield attributes of tomato under saline conditions, which could be used as a useful strategy in order to enhance the tolerance of tomato plants to salinity and biological yield.

#### **Acknowledgements**

The authors acknowledge the Ministry of Higher Education and Scientific Research of Tunisia.

#### **Conflict of interests**

The authors declare that the research was conducted in the absence of any commercial or relationships that could lead to a conflict of interest.

#### **Disclosure**

The authors alone are responsible for the content and writing of the paper.

### **Author details**

Salma Wasti1,2,3, Salwa Mouelhi1 , Feriel Ben Aïch1,2,3, Hajer Mimouni1 , Salima Chaabani1,2,3 and Hela Ben Ahmed1,2,3\*

1 Laboratory of Plant, Soil and Environment Interactions (LR21ES01), Faculty of Sciences of Tunis, Manar University, Tunis, Tunisia

2 Mixed Tunisian-Morocan Laboratory of Plant Physiology, Biotechnology and climate change LR11ES09, Faculty of Sciences of Tunis, University of Tunis El Manar II, Tunis, Tunisia

3 Faculty of Sciences Semlalia, University Cadi Ayyad Marrakech, Morocco

\*Address all correspondence to: benahmed\_hela@yahoo.fr

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown… DOI: http://dx.doi.org/10.5772/intechopen.106769*

#### **References**

[1] Hashemi A, Abdolzadeh A, Sadeghipour HR. Beneficial effects of silicon nutrition in alleviating salinity stress in hydroponically grown canola, Brassica napus L., plants. Soil Science & Plant Nutrition. 2010;**56**:244-253

[2] FAO. Land and plant nutrition management service. 2008

[3] Parida A, Das A. Salt tolerance and salinity effect on plants. Ecotoxicology and Environmental Safety. 2005;**60**:324-349

[4] Cuartero J, Fernandez-Munoz R. Tomato and salinity. Scientia Horticulture. 1999;**78**:83-125. DOI: 10.1016/S0304-4238(98)00191-5

[5] Najla S, Vercambre G, Pagès L, Grasselly D, Gautier H, Génard M. Tomato plant architecture as affected by salinity: Descriptive analysis and integration in a 3-D simulation model Botany. Botanique. 2009;**87**(10):893-904. DOI: 10.1139/ B09-061

[6] Ors S, Ekinci M, Yildirim E, Sahin U, Turan M, Dursun A. Interactive effects of salinity and drought stress on photosynthetic characteristics and physiology of tomato (Lycopersicon esculentum L.) seedlings. Bottomline. 2021;**137**:335-339. DOI: 10.1016/j. sajb.2020.10.031

[7] Movahhedi-Dehnavi M, Behzadi Y, Niknam N, Mohtashami R. Salicylic acid mitigates the effects of drought and salinity on nutrient and dry matter accumulation of Linseed. Journal of Plant Process and Function. 2019;**8**:31

[8] Fabre R, Duval M, Benoit B. Jeannequin. Influence de la salinité sur la qualité gustative et le rendement de

tomates greffées cultivées hors-sol sous serre chauffée dans le Sud de la France. Cahiers Agricultures, EDP Sciences. 2011;**20**:266

[9] Shaukat K, Zahra N, Hafeez MB, Naseer R, Batool A, Batool H, et al. Role of salicylic acid–induced abiotic stress tolerance and underlying mechanisms in plants. In: Aftab T, Naeem M, editors. Emerging Plant Growth Regulators in Agriculture: Roles in Stress Tolerance. 2022. pp. 73-98

[10] Gharbi E, Martínez JP, Ben Ahmed H, Fauconnier ML, Lutts S, Quinet M. Salicylic acid differently impacts ethylene and polyamine synthesis in the glycophyte Solanum lycopersicum and the wild-related halophyte Solanum chilense exposed to mild salt stress. Physiologia Plantarum. 2016;**158**(2):152-167. DOI: 10.1111/ ppl.12458

[11] Mimouni H, Wasti S, Manaa A, Abdallah C, Vandoorne B, Lutts S, et al. Does salicylic acid (SA) improve tolerance to salt stress in plants? A study of SA effects on tomato plant growth, water dynamics, photosynthesis, and biochemical parameters. OMICS. 2016;**20**:180-190

[12] Wasti S, Mimouni H, Smiti S, Zid E, Ben Ahmed H. Enhanced salt tolerance of tomatoes by exogenous salicylic acid applied through rooting medium. OMICS. 2012;**16**:4. DOI: 10.1089/ omi.2011.0071

[13] Behera TK, Krishna R, Ansari WA, Aamir M, Kumar P, Kashyap SP, et al. Approaches involved in the vegetable crops salt stress tolerance improvement: Present status and way ahead. Frontiers in Plant Science. 2021;**12**:787292. DOI: 10.3389/fpls.2021.787292

[14] Ben Ahmed H, Sayeh I, Manaa A, Ghidaoui J, Zid E. Varietal differences in salinity tolerance and mineral nutrition in tomatoes (Solanum lycopersicum). In: The Proceedings of the International Plant Nutrition Colloquium XVI. UC Davis. 2009. Available from: https:// escholarship.org/uc/item/65b1n6h9

[15] Manuel Almeida Machado R, Paulo Serralheiro R. Soil salinity: Effect on vegetable crop growth. Management practices to prevent and mitigate soil salinization. Horticulturae. 2017;**3**:30

[16] Manaa A, Gharbi E, Mimouni H, Wasti S, Aschi-Smiti S, Lutts S, et al. Simultaneous application of salicylic acid and calcium improves salt tolerance in two contrasting tomato (Solanum lycopersicum) cultivars. South Africa Journal of Botany. 2014;**95**:32-39

[17] Mohammadi H, Rahimpour B, Pirasteh-Anosheh H, Race M. Salicylic acid manipulates ion accumulation and distribution in favor of salinity tolerance in Chenopodium quinoa. International Journal of Environmental Research and Public Health. 2022;**19**:1576

[18] Pirasteh-Anosheh H, Emam Y, Sepaskhah AZ. Improving barley performance by proper foliar applied salicylic-acid under saline conditions. International Journal of Plant Production. 2015;**9**:467

[19] El-Taher AM, Abd El-Raouf HS, Osman NA, Azoz SN, Omar MA, Elkelish A, et al. Effect of salt stress and foliar application of salicylic acid on morphological, biochemical, anatomical, and productivity characteristics of Cowpea (*Vigna unguiculata* L.). Plants. 2022;**11**:115. DOI: 10.3390/plants11010115

[20] Noreen S, Ashraf M, Akram NA. Does exogenous application of salicylic acid improve growth and some key

physiological attributes in sunflower plants subjected to salt stress? Journal of Applied Botany and Food Quality. 2011;**84**:169-177

[21] Idrees M, Khan MMA, Aftab T, et al. Salicylic acid induced physiological and biochemical changes in lemongrass varieties under water stress. Journal of Plant Interactions. 2010;**5**:293-303

[22] Abdi G, Hedaya M, Askari N. Effect of different concentrations of salicylic acid on growth and flowering of marigold (*Tagetes erecta*). In: Proceeding of the 6th Iranian Horticultural Science Congress. Rasht, Iran; 2009. pp. 12-15

[23] Bolarin MC, Perez-Alfocea F, Cano EA, Estañ MT, Caro M. Growth, fruit yield, and ion concentration in tomato genotypes after pre-emergence and post-emergence salt treatments. Journal of American Society. 1993;**118**:655-660

[24] Dolatabadian A, Modarres Sanavy SAM, Ghanati F. Effect of salinity on growth, xylem structure and anatomical characteristics of soybean. Notulae Scientia Biologicae. 2011;**3**(1):41-45

[25] Lauchli A, Grattan SR. Plant growth and development under salinity stress. In: Jenks MA, Hasegawa PA, Jain SM, editors. Advances in Molecular-breeding Toward Drought and Salt Tolerant Crops. Dordrecht, Netherlands: Springer-Verlag; 2007. pp. 1-32

[26] Kinsou E, Amoussa AM, Mensah ACG, Kpinkoun JK, Assogba Komlan F, Ahissou H, et al. Effet de la salinité sur la floraison, la fructification et la qualité nutritionnelle des fruits du cultivar local Akikon de tomate (Lycopersicon esculentum Mill.) du Bénin. International Journal of Biological *Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown… DOI: http://dx.doi.org/10.5772/intechopen.106769*

and Chemical Sciences. 2021;**15**(2):737- 749. Available from: http://indexmedicus. afro.who.int

[27] Shakirova FM. Role of hormonal system in the manisfestation of growth promoting and anti-stress action of salicylic acid. In: Hayat S, Ahmad A, editors. Salicylic Acid. A Plant Hormone. Dordrecht. Netherlands: Springer; 2007. pp. 69-89

[28] Javaheri M, Mashayekhi K, Dadkhah A, Tavallaee FZ. Effects of salicylic acid on yield and quality characters of tomato fruit (*Lycopersicum esculentum* Mill.). International Journal of Agriculture and Crop Sciences. 2012;**4**(16):1184-1187

#### **Chapter 2**

## Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology and Alternative Tolerance Options

*Rowland Maganizo Kamanga and Patrick Alois Ndakidemi*

#### **Abstract**

Tomato is an important fruit vegetable in the world, as a nutritional source and an income option for a majority of resource constrained households. However, tomato supply in developing countries is often fluctuating, with high scarcity in both supply and quality during rainy season. Unlike many crops, cultivation of tomato is a challenging task during rainy season, with high pest and disease infestation. Hence, dry season is the most favorable period for tomato cultivation. However, inadequate water supply poses a yet another significant hurdle, as the crop requires high soil moisture for optimum growth. According to a landmark study by FAO, Tomato has a yield response factor of 1.05, which signifies that a smaller decline in water uptake results into a proportionally larger decline in yield. Moreover, over the years, there have been increasing reports of soil salinization, which imposes similar effects to drought stress through osmotic effects of Na+ in the soil solution and oxidative stress through excessive generation of reactive oxygen species. This chapter will dissect how tomato plants respond to these abiotic stress factors on physiological, anatomical, and molecular levels and suggest options to improve the crop's productivity under these constraining environments.

**Keywords:** drought, salinity, physiology, acclimation, osmotic tolerance

#### **1. Introduction**

Global changes in the climate scenario undeniably pose insurmountable challenge on global food supply system. Formerly agriculturally productive lands are insidiously becoming unarable. Yet, global population is steadily increasing, projected to reach an insane 9.8 billion by 2050 [1]. Therefore, finding ways to sustain agricultural productivity in light of the prevailing and worsening climate to support the growing population is one of the current and future's major global hurdles. Persistent droughts, extreme temperatures, soil salinization, and heat stresses have gradually become abiotic norms in the agricultural setting.

Tomato is among the most commercially important fruit vegetables globally [2, 3]. In one of the FAO's milestone publications on crop water relations, tomato was established to have a yield response factor (Ky) of 1.05, indicating that a small decline in water uptake results into a proportionally larger yield decrease [4–6]. This substantiates the need for development of cultivars that are able to maintain yield or exhibit less yield decline under limited water conditions. Worldwide, agricultural productivity is confronted with accelerating environmental constraints such as drought and salinity. Coupled with the global changes in climate, water stress is progressively becoming a major environmental factor limiting plant growth, development, and yield [7]. Drought and salinity stress impose somewhat similar effects on growth of crop plants, as both result into reductions in soil water availability and plant water uptake capacity. When soil water potential and plant's turgor fall below a threshold, such that normal plant functioning is perturbed, the soil is said to be droughted [8] or in a state of water stress. Some authors refer to soil as droughted when plant's water deficiency results from evaporative demand of the atmosphere exceeding plant roots' capacity to extract soil water [9]. It is indicated that initial reductions in shoot growth under salinity stress are due to increases in plants' osmotic pressure due to heavy presence of salts around roots, resulting into hormonal signals that eventually reduce stomatal conductance and consequently growth [10]. These effects are similar to those generated by drought stress. Tomato (*Solanum lycopersicum* L.) is recognized as a crop of an immense economic importance globally [2]. What is more is that drought and soil salinity have considerable impacts on its production [11, 12]. Present understanding proves that water stress perturbs various physiological and biochemical processes [7, 13–16] eliciting expression of various stress-related genes [12, 17, 18]. Therefore, in order to achieve the required knowledge for attainment of water stress tolerance, it remains imperative to couple physiological analysis's descriptive power with biochemical, morphological, and transcriptomic analysis [19] in carefully screened and selected varieties with proven differential tolerance under drought stress.

#### **2. Drought stress: an overview**

Plant water deficit develops as its demand exceeds the supply of water. The supply is determined by the amount of water held in the soil to the depth of the crop root system. The demand for water is set by plant transpiration rate or crop evapotranspiration, which includes both plant transpiration and soil evaporation. Evapotranspiration is driven by the crop environment as well as major crop attributes such as plant architecture, leaf area, and plant development. Drought stress is often measured by the Palmer Index (the Palmer drought severity index, PDSI), a regional drought index commonly used for monitoring drought events and studying areal extent and severity of drought episodes [20]. The index uses precipitation and temperature data to study moisture supply and demand using a simple water balance model. Water moves into the plant within a physical system also known as the soilplant-atmosphere continuum (SPAC). Here, water is driven through the plant from the soil to the atmosphere by the difference in water potential between the atmosphere (very low potential) and the soil (relatively high potential when wet).

Plants often receive excessive radiation, out of which only a small fraction is used for photosynthesis (photosynthetically active radiation), while the rest is dissipated as heat and transpiration [21], this led to the term "transpirational cooling." Transpiration functions to cool leaves relative to ambient temperatures when the environmental energy load on the plant is high, without which plant leaves could heat up to lethal temperatures [22]. When a leaf transpires, leaf water potential becomes

#### *Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

more negative (lowers), creating a water potential gradient (pull) that drives water movement into the plant (assuming more water is available in the soil). As the soil gets drier, it is necessary that leaf water potential be reduced further in order to create the required pull to drive water into the plant leaf.

This brings a concept of osmotic adjustment (OA), defined as the net accumulation of solutes after the plant has been exposed to a predetermined rate of water deficit [23]. OA has been suggested as a prime drought stress adaptive engine in support of plant production. Osmotic adjustment (OA) and cellular compatible solute accumulation are widely recognized to have a role in plant adaptation to dehydration mainly through turgor maintenance and the protection of specific cellular functions by defined solutes. A typical leaf cell comprises a battery organic and inorganic osmolytes (osmotically active solutes), such as soluble sugars, proline, and glycine betaine, which determine the leaf osmotic potential. Relatively, osmotic potential is lower than leaf water potential, whose difference is what constitutes turgor potential, a critical determinant of cellular growth and function, devoid of which collapses the cells and wilts the leaves. A lower turgor is typified with stomata closure (as an attempt to reduce transpiration), this reduction reduces intercellular CO2 concentration (Ci), consequently downregulating CO2 fixation and photosynthetic assimilation [7, 24] and an increase in leaf temperature [18]. Rise in temperature may get excessive, causing heat damage to the leaf especially under hotter environments. Therefore, turgor maintenance and transpiration are two critical aspects for plants growing under dehydrated conditions. Turgor maintenance can be maintained by sustaining water uptake to keep leaf water potential higher or through accumulation of osmolytes (osmotic adjustment).

At a whole plant level, transpiration rate can be controlled by limiting total leaf area. For example, two plants growing in a pot of similar volume, a large plant will require irrigation more frequently than a smaller one. Reduction of plant size and growth rate has therefore been a key revolutionary feature for plants' adaptation to drier environments [25]. As such, it has been observed that as water deficit becomes severe, older leaves desiccate and shed off first as an attempt to reduce leaf area and slow down on water requirement, while younger leaves maintain stomatal opening and carbon assimilation. At the crop level, the relationship between plant size and the demand for water can be extrapolated by measurement of leaf area index (LAI), which expresses total area of live leaves per unit ground surface. When LAI is high, crop evapotranspiration (ET) also increases, at least until LAI reaches a maximum threshold beyond which ET does not increase. As the crop matures and leaves senesce, LAI is reduced and so does evapotranspiration. In response to desiccation, growth regulating hormone abscisic acid (ABA) is produced in the shoot, inducing a cascade of responses such as arrested growth, stomatal closure, and reproductive failure. ABA is also produced in the root in direct response to the drying soil and its hardness as it dries. Root ABA is translocated to the shoots via the transpiration stream, eliciting stomatal closure or arrested growth before any water deficit develops in the shoot. This "hormonal or chemical root signal" may therefore serve as an "early warning system" to the plant. This results into the ABA-dependent pathway of signal transduction under drought stress. In this pathway, ABA induces novel protein synthesis, which regulates expression of numerous "ABA responsive" genes. Alternatively, ABA may also regulate stress responsive genes without novel protein synthesis. These gene products are either functional (e.g., water-channel proteins or key enzymes) or regulatory (e.g., protein kinases), and they are involved in mediating various cellular responses. Presently, thousands of "drought stress responsive genes" have been identified that are either upregulated or downregulated under dehydration.

#### **2.1 Responses of tomato plants to drought stress**

Physiologically, photosynthesis is one of the highly regulated, sensitive, and primary traits affected by drought [26, 27]. Hence, ability to maintain photosynthetic capacity under water stress deserves solemn consideration when screening for drought stress. Ueda et al. [28] observed that water and salinity stresses downregulate photosynthesis through stomatal and non-stomatal limitations. Yuan et al. [7] observed that under different water stress conditions, reasons for decline in photosynthetic rates are different; with stomatal limitations being more apparent under mild stress while non-stomatal limitations were more prevalent under moderate and severe water stress. This may suggest that severing water stress affects photosynthesis, principally via photosystem damage, inhibition of RuBISCO enzyme and other enzyme activities [29], and these non-stomatal effects may be even more apparent in sensitive cultivars. Furthermore, water stress affects photosynthesis through stomatal closure triggered by root to shoot signaling after sensing lower plant water potential. Thus, cultivars that present higher stomatal conductance under water stress conditions indicate a higher adaptability to water stress [30]. A consequence of inhibited photosynthesis is downregulation of plant growth; however, this cause-effect relationship remains difficult to entangle [31]. Under water stress, accumulation of soluble sugars and other osmolytes has been implicated in osmotic adjustment in tomatoes. Several studies have thus observed and correlated an increase in sugars and proline accumulation with drought tolerance [32, 33]. As a consequence of photosynthetic downregulation, drought stress often results into accumulation of reactive oxygen species (ROS), which damage photosynthetic machinery and cell membranes consequently resulting into cell death [13, 34]. Malondialdehyde is a widely used marker for lipid peroxidation and shows greater accumulation under abiotic stresses [7, 35]. Cell membrane stability and electrolyte leakage have also emerged as important tools in assessing membrane damage elicited by abiotic stress [36, 37].

#### **3. Salinity stress: an overview and effects**

The global consequences of the rapidly changing climate scenario imply that the environment for crop growth and development is gradually becoming unbearably altered. Soil salinization for one has victimized agriculture since time immemorial and has remained an important factor constraining worldwide crop productivity [38]. As a result, remarkable strides have been made in unmasking plants' responses and tolerance mechanisms to salinity stress. Deposition of salts in agricultural fields is principally through rain and wind and in rare cases through weathering of rocks [39]. It is estimated that over 800 million hectares of land are saline representing more than 6% of world's land area [31]. Spatially, soil salinity is most widespread in arid and semiarid regions in addition to sub-humid and humid climatic conditions. In most cases, these regions experience lower precipitation, yet suffer from higher evapotranspiration rates. This imbalance results into capillary transport of salts from the water table to the ground surface [40]. There are various types of salts that accumulate in the soil and water to agriculturally lethal levels. However, sodium chlorides (NaCl) are considered the most soluble and abundantly released salts, hence have been the subject of considerable research attention insofar as soil salinity is concerned. Soil salinity increases electrical conductivity of soil, hence soils are

#### *Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

characterized as saline when its ECe is at least 4 dS/m at 25°C [41], approximately 40 mM NaCl, with about 15% exchangeable sodium [42].

Plants' responses to soil salinity are governed by complex interactions of morphological, physiological, and biochemical processes, thereby affecting plants from seed germination, vegetative growth, reproductive development [42], and uptake of water and soil nutrients [43]. The complexity of salinity stress renders it particularly difficult to manage as it is associated with interlinked yet dissimilar effects that require different tolerance strategies. The first observable primary effect of salinity on plant growth is the reduction of water uptake capacity of plants. Usually, this effect is as a result of salts outside the roots, which increase the osmotic pressure of water making it harder for plants to take up water [31]. This osmotic component of salinity is rapid, progressing a few hours after encountering soluble salts and is characterized by decreases in new shoot growth, through reductions in leaf expansion rates, slow new leaf emergence, and lateral buds development. As a consequence of the resultant decline in soil water potential and subsequent cell dehydration, osmotic stress induces stomatal closure and a decline in photosynthetic activity that eventually chucks growth [28, 44]. In addition, soil salinity may result into ion toxicity and nutritional imbalances. Na<sup>+</sup> and K+ compete for binding sites, due to their similarity in physicochemical properties [45], such that excess availability of Na+ in the growth media results into replacement of K<sup>+</sup> by Na+ in some key biochemical reactions [42], which may become inhibitory to some enzymes [46]. It is well understood that most enzymes rely on K+ as a cofactor and can thus not be substituted by Na<sup>+</sup> . Thereby, maintaining an optimal Na+ /K+ ratio has emerged a crucial aspect of salinity tolerance [47]. The ion-specific phase is relatively slow and begins when salts accumulate to lethal concentrations particularly in older leaves that have ceased expanding and eventually die. According to Munns and Tester [31], ionic stress becomes a major concern in crop plants with uncontrollable accumulation of ions in the shoots coupled with an inability to tolerate the accumulated ions. Therefore, maintenance of a lower Na+ accumulation in relation to essential ions such as K<sup>+</sup> , Mg2+, and Ca2+ is a desirable trait under salinity stress. Toxic accumulation of Na<sup>+</sup> and Cl− salts in the cytosol and osmotic-effect-induced reductions in water uptake result into metabolic imbalances, which in turn cause oxidative stress [48]. Meanwhile, it is widely accepted that accumulation of reaction oxygen species (ROS) accounts for a major part of damage caused to macromolecules and cellular structure by most abiotic stresses [49] suggesting that generation of ROS might be the prime cause of lethality in stressed organisms. Under optimal conditions, plants' cellular homeostasis is dependent on a delicate balance of multiple interlinked pathways. However, water stress disrupts that balance, uncoupling the pathways resulting into transferring of high energy state electrons to oxygen, which generates reactive oxygen species [50, 51]. These include hydrogen peroxide (H2O2), superoxide radicles (O2**•** − ), singlet oxygen (1 O2), and hydroxyl radicles (OH**•**). When their generation exceeds their scavenging, they are potentially toxic and capable of causing oxidative stress to proteins, DNA, and lipids [13, 52, 53]. Therefore, tolerance to salinity stress requires a combination of multiple strategies and mechanisms that confront osmotic stress, specific ion toxicity and scavenge reactive oxygen species.

#### **3.1 Tolerance mechanisms to salinity stress**

As a result of the widespread nature of salinity stress, plants have developed multiple mechanisms and strategies to confront salinity stress. Tolerance to salinity stress falls within three main categories; osmotic tolerance, ion exclusion, and tissue tolerance (**Figure 1**). A yet fourth tolerance strategy pertains to tolerance to oxidative stress elicited by excessive generation of ROS. Osmotic stress inhibits ability of plants to take up water due to excessive presence of salts around the roots. Thereby first mechanism, termed osmotic tolerance, is targeted at sustaining water uptake in plants and ensuring a well-hydrated leaf status of plants to maintain key metabolic activities such as photosynthesis. This is regulated by long distance signals that reduce shoot growth [54] way before Na+ accumulates to the shoots. ROS and Ca2+ waves are speculated to be involved in the long-distance signaling under osmotic tolerance [55]. One important mechanism through which plants confront osmotic stress is through accumulation of solutes to balance extra osmotic pressure generated in the soil solution to maintain turgor [18]. This can be achieved by excluding saline ions from accumulating in the shoots and principally relying on accumulation of organic osmolytes such as sugars, proline, glycine betaine, etc. However, controversy sparks from this strategy as it comes with a larger trade-off in the form of energy cost [56]. That notwithstanding, this strategy is employed particularly among glycophytes through selective uptake of ions by roots, excluding uptake of Na<sup>+</sup> and Cl− , preferentially loading K+ in the xylem vessels, and controlling Na+ loading and unloading of Na+ from the xylem in the upper part of the roots, stems, and petiole [10]. Cognizant of the energy cost of synthesizing organic solutes for osmotic adjustment, some plants, mostly halophytes, rely on accumulation of Na+ as a cheap osmoticum. This way, the plants transport Na+ to the shoots to levels bearable and sequester them into vacuoles so as not to interfere with key cytosolic metabolic activities [57]. Works leading to the discovery of tissue tolerance as a strategy in plants were inspired by an earlier finding that in vitro, halophytic enzymes were not any more tolerant to high salt than those of glycophytic plants [58, 59]. Besides, several species have reported higher tissue Na+ concentrations in leaves that are still functioning [60, 61]. When Na<sup>+</sup> /Cl− accumulates in the vacuole, K+ and organic solutes must accumulate in the cytoplasm to balance

**Figure 1.** *A summary of mechanisms of salinity tolerance in tomato plants.*

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

the osmotic pressure of ions in the vacuole. Common organic osmolytes in tomatoes are proline [62] and soluble sugars [24, 63].

All these compounds are found under both drought and salt stress and accumulate in higher levels in plants adapted to such environments. Under salt stress, their accumulation reflects more of an osmotic response than salt-specific (ionic) response. This strategy is termed tissue tolerance and in tomatoes, it is aided by Na<sup>+</sup> /H<sup>+</sup> antiporters NHX, isoforms *SlNHX3* and *SlNHX4* [64]. It is important to note that plants transpire 30–70% more water than is used for cell expansion [10]. Salts carried in the transpiration stream are deposited in leaves as the water evaporates, gradually building up to toxic levels. In older leaves, salt toxicity becomes much higher than younger leaves since they are no longer expanding and cannot dilute incoming salts. Eventually, the salt concentration becomes high enough to kill the cells. Hence, some plants rely on Na<sup>+</sup> exclusion, to reduce the rate at which salt accumulates in transpiring organs. This can be achieved through (1) root cells and can selectively avoid uptake of Na<sup>+</sup> (2) preferentially loading of K<sup>+</sup> into the xylem at the expense of Na<sup>+</sup> and (3) unloading of Na<sup>+</sup> from the xylem, this is aided in tomato by high-affinity K<sup>+</sup> transporters (SlHKT1;2). Being a glycophytic plant, tomato is less efficient in sequestering Na<sup>+</sup> in the vacuoles but relies predominantly on exclusion of Na<sup>+</sup> from the leaves.

#### **3.2 Screening techniques for drought and salinity tolerance**

In view of the devastating effects of drought and salinity coupled with sensitivity of this agronomically important crop, it is substantiated to develop cultivars that are able to maintain yield or exhibit less yield decline under these environments. Such breeding goals can be aided with proper screening and selection for water stress-tolerant cultivars. Various techniques and parameters have been derived from screening for drought tolerance [65, 66]. A classical approach to investigating plants' responses to abiotic stresses is to use two genotypes with contrasting tolerance reputations. Some have argued that this approach is narrow, hence have advocated for the broadening of these types of analyses by using several genotypes before speculating about a species' performance [67]. Furthermore, when selecting a few contrasting genotypes, it is necessary to take into account the potential variability of the trait under study within the population, especially crops and plants with determinate and indeterminate growth habits such as tomato. In such cases, derivation of salt tolerance indices obtained as relative decreases in plant biomass by comparing plant biomass of stressed and control plants [68] is imperative. Stress susceptibility index (SSI) serves as a reliable measure of sensitivity to stress as it considers the intensity of stress and performance ratio between stress and their respective controls [69]. That notwithstanding, screening techniques need to be supplemented with other techniques to increase their reliability. Cluster analysis is one dependable tool that allows self-grouping of cultivars into groups of similar characteristics and has been widely used as a screening tool in tomato [24, 65, 66]. For reference to a variety of screening methods and their merits, refer to [70].

#### **4. Salinity and water stress: where is the synergy?**

Firstly, it is important to understand that plants' responses to salinity stress occur in two distinct temporal phases [71]: a rapid response to the increase in external

osmotic pressure, and a slower response due to the accumulation of Na+ in leaves. Hence, in order to correctly dissect the physiological mechanisms associated with salinity tolerance of plants, it is necessary to first identify whether their growth is being limited by the osmotic effect of the salt in the soil or the toxic effect of the salt within the plant. According to [31], in the first few hours occurring immediately after plant roots are exposed to a saline media, plant's shoot growth is considerably reduced, largely as a result of osmotic effect of salts "outside" the plant roots. Evidently, plants experience a lower rate of leaf expansion, slower emergency of newer leaves, and slower development of lateral buds consequently forming fewer branches and lateral shoots. It is important to note that shoot growth is far much sensitive to the osmotic effects than root growth. This phenomenon is also common in drying soils under drought conditions. It has been suggested that reduction in leaf area development relative to root growth would decrease the water use by the plant, thus allowing it to conserve soil moisture and prevent an escalation in the salt concentration in the soil [31]. Relatively, it is the osmotic stress component of salinity stress that exhibits both an immediate and greater effect on growth than the ionic stress. The latter is manifested much later and lesser. Ionic effects of salinity stress are only higher either at very high salinity levels or in extremely sensitive species such as rice whose ability to control Na<sup>+</sup> transport is limited.

Now, the question may remain as to whether these osmotic responses are salt and species-specific. Experiments in maize [72, 73], rice [74] as well as wheat and barley [75] have all recorded rapid and transient reductions in leaf expansion rates after a sudden increase in salinity. Likewise, similar changes were reported when plants are exposed to KCl, mannitol, or polyethylene glycol (PEG) [76]. These results are indicative that the responses are neither salt- nor species-specific. This first phase growth reduction is quickly apparent and is due to the salt outside the roots. It is essentially a water stress or osmotic phase, for which there is surprisingly little genotypic variation. The growth reduction is presumably regulated by hormonal signals coming from the roots. It is from this point of view that salinity stress synonymizes drought stress, hence the usage of the term "physiological drought" by some authors [62, 77]. **Figure 2** shows this synergy, drought-specific responses involve synthesis of ABA and induction of ABA responsive genes involved in synthesis of water channels, enzymes, and protein kinases.

#### **4.1 Comparative osmotic responses to salt and drought stress**

Plants growing under salt stress are faced with three prime costs; (1) the cost of excluding Na+ from uptake by roots, (2) the cost of compartmentalizing/sequestering Na+ in the vacuole, and (3) that of excreting the salt through salt glands. In tomatoes, the latter cost is of less importance as tomatoes do not have the salt glands. Under drought stress, the prime cost is to synthesize organic osmolytes, a far much higher cost. While it remains unclear whether plants growing under saline media produce lesser organic solutes compared with those growing under non-saline media, a comparison of four tomato genotypes growing under PEG and NaCl at an isotonic solution, much greater accumulation of soluble sugars was observed under PEG than NaCl [78]. Correspondingly, the tomato plants growing under NaCl grew much better than under the isotonic PEG solution. This result suggests the higher cost of synthesizing organic osmolytes in tomatoes on growth, hence it may follow that plants growing under saline conditions grow faster than under non-saline media. However, this conclusion may not be overarching, as equivocal results have been obtained in other species, notably [10].

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

**Figure 2.**

*The synergy of drought and salinity stresses. Osmotic stress and oxidative stress are common links of both salinity and drought stress, whereas salt specific response is ionic toxicity (Na<sup>+</sup> and Cl− ) and drought-specific responses include synthesis of ABA in either shoots or roots that trigger expression of ABA responsive genes.*

#### **5. Learning from tomato wild relatives**

Despite that tomato remains sensitive to drought and salt stress, the genus *Solanum* has extensive wealth of genetic variation existing in wild relatives. Tomato, for example, has a number of wild relatives with remarkable reputation for tolerance to drought and salt stress, such as *Solanum pennellii*, *S. habrochaites*, *S. pimpinellifolium*, *S. hirsutum*, *Lycopersicum chillense*, and *L. peruvianum.* As such, they represent a valuable system in which to study local adaptation to drought and salt stress. A number of comparative studies have been conducted to evaluate physiological and molecular responses of cultivated tomato (*S. lycopersicum)* in comparison with wild relatives. For example, Egea et al. [17] reported substantial physiological differences, with the wild relative *Sp* leaves showing greater ability to avoid water loss and oxidative damage under drought stress. Similar results were also found in another wild relative *S. habrochaites* under root-chilling-induced water stress, in which *Sh* exhibited higher shoot turgor through enhanced stomata closure relative to cultivated tomato, which failed to close stomata and consequently wilted [79]. QTL mapping revealed a single QTL coincidental with the gene or genes contributing to shoot turgor maintenance under root chilling residing on chromosome 9 region that have been associated with abiotic stress tolerance in cultivated tomato. Under salinity stress, another study showed that *Sp* was able to reduce water loss by regulating transpiration through reduced stomatal density and aperture [18]. Furthermore, *Sp* leaves had larger and more turgid cells occupied by a giant vacuole, which was associated with higher water and Na+ accumulation. On Na<sup>+</sup> homeostasis, the wild relative had higher expression of SpHKT1;2 and SpSOS1, which played an important role in Na+ translocation from root to shoot, and therefore, in the determination of the included behavior in the wild species, which was in concordance with the higher transcript levels of Na<sup>+</sup> vacuolar transporters SpNHX3 and SpNHX4 in *Sp* leaves. An association study in 94 genotypes of *S. pimpinellifolium* to identify variations linked to salt tolerance traits

(physiological and yield traits under salt stress) in four candidate genes identified five SNP/Indels in DREB1A and VP1.1 genes that explained substantially, phenotypic variation for various salt tolerance traits [80].

#### **6. Improving salt and drought tolerance in tomato**

Salinity stress affects many aspects of physiology and biochemistry of plants and, subsequently, yield. Growing knowledge and advances in molecular techniques provide room and opportunity for quicker enhancement of salt tolerance in tomatoes. Even though genetic transformation could become a powerful tool in plant breeding, it is necessary to integrate the growing knowledge from plant physiology with molecular breeding techniques. Notwithstanding the many relatively salt tolerant wild relatives of the cultivated tomato, it has proved difficult to enrich elite lines with genes from wild species that confer tolerance because of the large number of genes involved, most of them with small effect in comparison to the environment [81]. Critical in breeding for salt and drought tolerance is the need for the new cultivars to be both tolerant and maintain attributes of higher yield and quality shown by modern cultivars. Hypothetically, susceptible but productive cultivars should be converted to tolerant cultivars, while maintaining all the very valuable characters current cultivars possess, making the introduction of genes conveying salt tolerance to elite cultivars by transformation an attractive option. However, the problem of drought and salt tolerance is complex and multigenic, requiring a battery of strategies. Instead, scientists have resorted to a range of cultural techniques, each contributing to a small extent to allow plants to withstand better the deleterious effects of salt.

For many years to recent, it was believed that salt tolerance was solely a factor of expression of genetic information counteracting effects of stress [82]. However, present understanding tells that plants can improve their physiological ability and adapt to severe stresses when pretreated (PT) with mild stress, a phenomenon termed acclimation [61, 83–85] as shown in **Figure 3**. During the plant response and acclimation to abiotic stress, important changes in biochemistry and physiology take place and many genes are activated, leading to accumulation of numerous proteins involved in abiotic stress tolerance. Benefits of acclimation to salinity stress have been linked to improved growth via effective vacuolar Na+ sequestration [61], improved survival rates [84], and reduced shoot Na+ accumulation [62, 85, 86]. The successful adaptation of cell lines to salinity suggests that a genetic potential for salt tolerance is present in cells of plants from which the lines were derived and that exposure of the cells to salt triggers the expression of this information.

In tomato, success stories of acclimation have been reported through seedling pretreatment with NaCl [62, 87], pre-exposure to salicylic acid [88, 89], and seed priming with NaCl [82]. Another study by Gémes et al. [90] showed that pretreatment of tomato plants with salicylic acid attenuated oxidative stress by reducing H2O2 generation under salt stress, suggesting a cross talk between salicylic acid and saltstress-induced ROS. H2O2 is considered functional link of cross-tolerance to various stressors, as also reported in rice under saline-alkaline stress [86]. Szepesi [91] found that salicylic acid pretreatment improved the acclimation of tomato plants to tolerance levels comparable to that of tomato's wild relative *L. pennellii*, a wild relative with a high reputation for stress tolerance. Humic acids pretreatment of tomato seedlings has also been explored and showed that seedlings primed by humic acids minimized the salinity stress by changing ion balance, promoting plasma membrane proton pumps activity and enhancing photosynthesis rate and plant growth [92].

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

#### **Figure 3.**

*A schematic of acclimation in tomato plants, wherein seedlings' previous exposure to a mild level of stress (salt or drought) primes tomato plants to exhibit faster and stronger responses to subsequent lethal stresses.*

Plant adaptation to abiotic stress has also been observed under drought stress. For example, a study by [93] showed that multiple exposures to drought stress trained transcriptional responses in Arabidopsis. In the study, it was shown that during recurring dehydration stresses, Arabidopsis plants displayed transcriptional stress memory demonstrated by an increase in the rate of transcription and elevated transcript levels of a subset of the stress-response genes (trainable genes). Four distinct types of dehydration stress memory genes in *Arabidopsis thaliana* have been further identified [94]. These observations of altered plants' subsequent responses following pre-exposure to various abiotic stresses by improving resistance to future exposures, have led to the concept of "stress memory" implying that during subsequent exposures, plants provide responses that are different from those during their first encounter with the stress. While these phenomena have not been reported in tomato, yet they might represent a general feature of plant stress-response systems and could lead to novel approaches for increasing the flexibility of a plant's ability to respond to the environment. In tomato, it has been shown that a moderate water deficit applied 10 days after anthesis induced acclimation to a subsequent more severe drought stress [95]. Similar results have also been reported in wheat [96]. It has been reported that plants exposed to one stress may show tolerance to other stresses, displaying a concept of cross-tolerance [86, 97, 98]. It is hypothesized that drought pretreatment could increase the tolerance to the osmotic effect, the main effect induced by salinity when moderate salt levels are used. This has been observed in tomato plants previously exposed to a drought stress pretreatment, which subsequently grew better than non-pretreated plants after 21 days of salt treatment [99]. Similar findings were reported by [100], who found improved salt tolerance of tomato plants following seedling pretreatment with PEG, a chemical drought (osmotic) stress simulator. This illustrates a concept of induced cross-tolerance (**Figure 4**), in which prior exposure to one stress induces tolerance to another stress, as opposed to inherent cross-tolerance that manifests itself as genetic correlation of gene expression under different stresses (**Figure 4**).

#### **Figure 4.**

*A schematic of cross-tolerance. Plants may exhibit inherent cross-tolerance, manifesting itself as genetic correlation of gene expression under different stresses. Cross-tolerance may also be induced by previous exposure to one stress that may develop tolerance to another stress compared with plants without prior exposure to any stress.*

Plant adaptation to stresses is a complex process, involving numerous physiological and biochemical changes. The key components in a typical stress-response relationship involve stress stimulus, perception of stress by signals, expression of stress-induced genes, and resultant changes at morphological, biochemical, and physiological levels [98]. The signaling and response pathways have been reported to overlap during exposure to different abiotic stresses, including reactive oxygen species (ROS), hormones, protein kinase cascades, and calcium gradients as common elements [101]. In a case of cross-tolerance, it has been suggested that specific proteins are induced by one kind of stress and are involved in the protection against other kinds of stress [97, 98], although a common mechanism has not been found.

Aside from the use of pretreatments, another route for enhancing salt and drought stress tolerance in tomato would be to graft cultivars on to rootstocks able to reduce the effect of external salt or drought on the shoot. This strategy could also provide the opportunity to growers of combining good shoot characters with good root characters. In tomato, grafting has previously been used to limit soil-borne and vascular diseases such as Fusarium. Over the years, application of grafting technique has been widened across various uses such as improving yield, fruit quality, low and high temperature as well as Fe chlorosis as outlined in [81]. In Citrus spp., for example, the positive effect of rootstock is related to the ability of the rootstock to exclude chloride [102, 103]. However, grafting has rarely been used to increase the productivity of vegetables growing under adverse conditions. In tomato, a commercial tomato cultivar Jaguar as scion has been grafted onto roots derived from the same genotype (J/J) or other cultivars' root stocks that increased fruit yield by more than 60% under salinity stress by regulating the transport of Na<sup>+</sup> and Cl<sup>−</sup> throughout the plant growth cycle, even after 90 days of salt treatment [104]. Similar results have also been reported by [105], further revealing that rootstock effect on the tomato salinity response depends on the shoot genotype. Furthermore, [106] also found higher improvements in vegetative growth as well as yield in a commercial tomato cultivar grafted on tomato wild relatives coupled with changes in morphological, physiological, and molecular attributes. The results suggest that the saline ion accumulation in leaves is predominantly controlled by the genotype of


*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

#### **Table 1.**

*List of some cultural techniques that have been used to enhance drought and salt tolerance in tomato and other crops.*

the rootstock, providing an alternative way of enhancing salt tolerance in tomato – quicker and least costly.

An observation has been made that acclimation ability to abiotic stress in tomatoes is dependent on degree of tolerance of the cultivar such that more salt-sensitive cultivars benefit more from the acclimation process than tolerant cultivars [62, 87].

### **7. Concluding remarks**

Despite being a crop of considerable agronomic importance, tomato remains a sensitive crop to droughts and salinity stress. Cultivation under these environments is an extremely challenging task; hence, it is imperative to develop tomato cultivars resistant to these adverse conditions. This, however, requires an understanding of their physiological and molecular mechanisms underpinning tolerance. This chapter has dissected in detail the key physiological and molecular changes that take place under both drought and salinity. These two stresses, albeit being distinct, pose considerable similarities and affect tomato growth in significantly comparable manners. The chapter also drew learning points from tomato's wild relatives that present the required variation for development of tolerant cultivated varieties. However, development of tolerant cultivars is often a long and costly endeavor and subject to country-specific regulatory frameworks. Moreover, considering the multigenic nature of drought and salt tolerance trait, the chapter suggests exploration of some quicker options that promote adaptation to adverse environments. In tomato, options such as acclimation, cross-tolerance, and grafting have proved effective in developing tolerance to abiotic and in some cases, biotic stress conditions (**Table 1**). These may provide some required short-term yield gains when cultivating tomato under adverse environmental conditions.

### **Conflict of interest**

The authors declare no conflict of interest.

### **Author details**

Rowland Maganizo Kamanga1 \* and Patrick Alois Ndakidemi2

1 Department of Horticulture, Lilongwe University of Agriculture and Natural Resources, Lilongwe, Malawi

2 School of Life Science and Bio-Engineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania

\*Address all correspondence to: rowlandkamanga5@gmail.com

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

#### **References**

[1] UN. World Population Projected to Reach 9.8 Billion in 2050, and 11.2 Billion in 2100. 2017. Available from: https:// www.un.org/development/desa/en/ news/population/world-populationprospects-2017.html. [Accessed: October 12, 2020]

[2] Schwarz D, Thompson AJ, Kläring H-P. Guidelines to use tomato in experiments with a controlled environment. Frontiers in Plant Science. 2014;**5**(November):1-16. DOI: 10.3389/ fpls.2014.00625

[3] Jangid KK, Dwivedi P. Physiological responses of drought stress in tomato: A review. International Journal of Agriculture, Environment and Biotechnology. 2016;**9**(February):5958

[4] Steduto P, Hsiao TC, Fereres E, Raes D. Crop yield response to water. In: FAO irrigation and drainage paper N° 66. Rome: FAO; 2012. p. 505

[5] Smith M, Steduto P. Yield response to water: the original FAO water production function. FAO Irrigation and Drainage Paper. 2012;**66**:6-13

[6] Johl SS. United Nations. Economic Commission for Western Asia., Food and Agriculture Organization of the United Nations., and Mu'assasat al-Baḥth al-ʻIlmī (Iraq), Irrigation and agricultural development: Based on an International Expert Consultation, Baghdad, Iraq, 24 February-1 March 1979. 2013

[7] Yuan XK, Yang ZQ, Li YX, Liu Q, Han W. Effects of different levels of water stress on leaf photosynthetic characteristics and antioxidant enzyme activities of greenhouse tomato.

Photosynthetica. 2016;**54**(1):28-39. DOI: 10.1007/s11099-015-0122-5

[8] Kramer PJ, Boyer JS. Water Relations of Plants and Soils. London: Elsevier Science; 1995

[9] Blum A. Crop responses to drought and the interpretation of adaptation. In: Drought Tolerance in Higher Plants: Genetical, Physiological and Molecular Biological Analysis. Dordrecht: Springer Netherlands; 1996. pp. 57-70

[10] Munns R. Comparative physiology of salt and water stress. Plant, Cell & Environment. 2002;**25**(2):239-250. DOI: 10.1046/j.0016-8025.2001.00808.x

[11] Saadi S, Todorovic M, Tanasijevic L, Pereira LS, Pizzigalli C, Lionello P. Climate change and Mediterranean agriculture: Impacts on winter wheat and tomato crop evapotranspiration, irrigation requirements and yield. Agricultural Water Management. 2015;**147**:103-115. DOI: 10.1016/J.AGWAT.2014.05.008

[12] Ijaz R et al. Overexpression of annexin gene AnnSp2, enhances drought and salt tolerance through modulation of ABA synthesis and scavenging ROS in tomato. Scientific Reports. 2017;**7**(1):12087. DOI: 10.1038/ s41598-017-11168-2

[13] Kamanga RM, Mbega E, Ndakidemi P. Drought tolerance mechanisms in plants: Physiological responses associated with water deficit stress in *Solanum lycopersicum*. Advances in Crop Science and Technology. 2018;**6**(3):362. DOI: 10.4172/2329-8863.1000362

[14] Soltys-Kalina D, Plich J, Strzelczyk-Żyta D, Śliwka J, Marczewski W. The

effect of drought stress on the leaf relative water content and tuber yield of a half-sib family of 'Katahdin'-derived potato cultivars. Breeding Science. 2016;**66**(2):328-331. DOI: 10.1270/ jsbbs.66.328

[15] Kamanga RM, Mndala L. Crop abiotic stresses and nutrition of harvested food crops: A review of impacts, interventions and their effectiveness. African Journal of Agricultural Research. 2019;**14**(3):118- 135. DOI: 10.5897/AJAR2018.13668

[16] Wang Y, Frei M. Stressed food—The impact of abiotic environmental stresses on crop quality. Agriculture, Ecosystems and Environment. 2011;**141**(3-4):271- 286. DOI: 10.1016/j.agee.2011.03.017

[17] Egea I et al. The drought-tolerant *Solanum pennellii* regulates leaf water loss and induces genes involved in amino acid and ethylene/jasmonate metabolism under dehydration. Scientific Reports. 2018;**8**(1):1-14. DOI: 10.1038/ s41598-018-21187-2

[18] Albaladejo I, Meco V, Plasencia F, Flores FB, Bolarin MC, Egea I. Unravelling the strategies used by the wild tomato species *Solanum pennellii* to confront salt stress: From leaf anatomical adaptations to molecular responses. Environmental and Experimental Botany. 2017;**135**:1-12. DOI: 10.1016/j. envexpbot.2016.12.003

[19] Zhu M et al. Molecular and systems approaches towards drought-tolerant canola crops. The New Phytologist. 2016;**210**(4):1169-1189. DOI: 10.1111/ nph.13866

[20] Alley WM. The palmer drought severity index as a measure of hydrologic drought. Journal of the American Water Resources Association. 1985;**21**(1):105- 114. DOI: 10.1111/J.1752-1688.1985. TB05357.X

[21] Maxwell K, Johnson GN. Chlorophyll fluorescence—A practical guide. Journal of Experimental Botany. 2000;**51**(345):659-668. DOI: 10.1093/ jxb/51.345.659

[22] Blum A. Drought resistance, wateruse efficiency, and yield potential—Are they compatible, dissonant, or mutually exclusive? Australian Journal of Agricultural Research. 2005;**56**(11):1159. DOI: 10.1071/AR05069

[23] Blum A. Osmotic adjustment is a prime drought stress adaptive engine in support of plant production. Plant, Cell & Environment. 2017;**40**(1):4-10. DOI: 10.1111/pce.12800

[24] Kamanga RM. Screening and differential physiological responses of tomato (*Solanum lycopersicum* L.) to drought stress. Plant Physiology Reports. 2020;**25**(3):1-4. DOI: 10.1007/ s40502-020-00532-6

[25] Poorter H, Jülich F. Interspecific variation in relative growth rate: On ecological causes and physiological consequences T. [Online]. Available from: https://www.researchgate.net/ publication/255663299. [Accessed: May 08, 2022]

[26] Chaves MM. Effects of water deficits on carbon assimilation. Journal of Experimental Botany. 1991;**42**(1):1-16. DOI: 10.1093/jxb/42.1.1

[27] Galmés J et al. Physiological and morphological adaptations in relation to water use efficiency in Mediterranean accessions of Solanum lycopersicum. Plant, Cell & Environment. 2011;**34**(2):245-260. DOI: 10.1111/j. 1365-3040.2010.02239.x

[28] Ueda A, Kanechi M, Uno Y, Inagaki N. Photosynthetic limitations of a halophyte sea aster (*Aster* 

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

*tripolium* L) under water stress and NaCl stress. Journal of Plant Research. 2003;**116**(1):65-70. DOI: 10.1007/ s10265-002-0070-6

[29] Cornic G, Fresneau C. Photosynthetic carbon reduction and carbon oxidation cycles are the main electron sinks for photosystem II activity during a mild drought. Annals of Botany. 2002;**89**(7):887-894. DOI: 10.1093/aob/ mcf064

[30] Medrano H, Escalona JM, Bota J, Gulías J, Ex JFL. Regulation of photosynthesis of C 3 plants in response to progressive drought: Stomatal conductance as a reference parameter. Annals of Botany. 2002;**89**:895-905. DOI: 10.1093/aob/mcf079

[31] Munns R, Tester M. Mechanisms of salinity tolerance. Annual Review of Plant Biology. 2008;**59**(1):651-681. DOI: 10.1146/annurev.arplant.59.032607. 092911

[32] Mohammadkhani N, Heidari R. Drought-induced accumulation of soluble sugars and proline in two maize varieties. World Applied Sciences Journal 2008;3(3):448-453. Available from: https://pdfs.semanticscholar.org/4e67/13f 4cd5fc7a45a43aa7962a9cb3e3fbba8d7.pdf. [Accessed: October 03, 2018]

[33] Alarcon JJ, Sanchez-Blanco MJ, Bolarin MC, Torrecillas A. Water relations and osmotic adjustment in *Lycopersicon esculentum* and *L. pennellii* during short-term salt exposure and recovery. Physiologia Plantarum. 1993;**89**(3):441-447. DOI: 10.1111/j.1399- 3054.1993.tb05196.x

[34] Sharma P, Jha AB, Dubey RS, Pessarakli M. Reactive oxygen species, oxidative damage, and antioxidative defense mechanism in plants under stressful conditions. Journal of Botany. 2012;**2012**:1-26. DOI: 10.1155/ 2012/217037

[35] Mekawy AMM, Abdelaziz MN, Ueda A. Apigenin pretreatment enhances growth and salinity tolerance of rice seedlings. Plant Physiology and Biochemistry. 2018;**130**:94-104. DOI: 10.1016/J.PLAPHY.2018.06.036

[36] Farooq S, Azam F. The use of cell membrane stability (CMS) technique to screen for salt tolerant wheat varieties. Journal of Plant Physiology. 2006;**163**(6):629-637. DOI: 10.1016/j. jplph.2005.06.006

[37] Jungklang J, Saengnil K, Uthaibutra J. Effects of water-deficit stress and paclobutrazol on growth, relative water content, electrolyte leakage, proline content and some antioxidant changes in Curcuma alismatifolia Gagnep. cv. Chiang Mai Pink. Saudi Journal of Biological Sciences. 2017;**24**(7):1505-1512. DOI: 10.1016/J.SJBS.2015.09.017

[38] Negrão S, Courtois B, Ahmadi N, Abreu I, Saibo N, Oliveira MM. Recent updates on salinity stress in rice: From physiological to molecular responses. Critical Reviews in Plant Sciences. 2011;**30**(4):329-377. DOI: 10.1080/ 07352689.2011.587725

[39] Rengasamy P. Soil processes affecting crop production in salt-affected soils. Functional Plant Biology. 2010;**37**(7):613. DOI: 10.1071/FP09249

[40] Ueda A et al. Comparative physiological analysis of salinity tolerance in rice. Soil Science & Plant Nutrition. 2013;**59**(6):896-903. DOI: 10.1080/00380768.2013.842883

[41] USDA-ARS. Research Databases. Bibliography on Salt Tolerance. In: Brown GE Jr. Riverside, CA: Salinity Lab. US

Dep. Agric., Agric. Res. Serv.; 2008. Available from: https://www.ars.usda. gov/pacific-west-area/riverside-ca/ us-salinity-laboratory/docs/researchdatabases/. [Accessed: May 31, 2019]

[42] Shrivastava P, Kumar R. Soil salinity: A serious environmental issue and plant growth promoting bacteria as one of the tools for its alleviation. Saudi Journal of Biological Sciences. 2015;**22**(2):123-131. DOI: 10.1016/J. SJBS.2014.12.001

[43] Gharaei A et al. Salinity effects on seed germination and seedling growth of bread wheat cultivars of Hamoun International Wetland in different scenarios. Granted by Sistan and Baluchestan Department of Environment. View project. 2011. Available from: http://www.uni-sz.bg [Accessed: May 31, 2019]

[44] Janda T, Darko É, Shehata S, Kovács V, Pál M, Szalai G. Salt acclimation processes in wheat. Plant Physiology and Biochemistry. 2016;**101**:68-75. DOI: 10.1016/J. PLAPHY.2016.01.025

[45] Marschner H, Marschner P. Marschner's Mineral Nutrition of Higher Plants. London: Academic Press; 2012

[46] Cuin TA, Shabala S. Compatible solutes reduce ROS-induced potassium efflux in Arabidopsis roots. Plant, Cell & Environment. 2007;**30**(7):875-885. DOI: 10.1111/j.1365-3040.2007.01674.x

[47] Assaha DVM, Ueda A, Saneoka H, Al-Yahyai R, Yaish MW. The role of Na+ and K+ transporters in salt stress adaptation in glycophytes. Frontiers in Physiology. 2017;**8**:509. DOI: 10.3389/ fphys.2017.00509

[48] Chinnusamy V, Zhu J, Zhu J-K. Gene regulation during cold acclimation in plants. Physiologia Plantarum. 2006;**126**(1):52-61. DOI: 10.1111/j.1399-3054.2006.00596.x

[49] Sairam RK, Rao KV, Srivastava G. Differential response of wheat genotypes to long term salinity stress in relation to oxidative stress, antioxidant activity and osmolyte concentration. Plant Science. 2002;**163**(5):1037-1046. DOI: 10.1016/ S0168-9452(02)00278-9

[50] Miller G, Suzuki N, Ciftci-Yilmaz S, Mittler R. Reactive oxygen species homeostasis and signalling during drought and salinity stresses. Plant, Cell & Environment. 2010;**33**(4):453-467. DOI: 10.1111/j.1365-3040.2009.02041.x

[51] Mittler R. Oxidative stress, antioxidants and stress tolerance. Trends in Plant Science. 2002;**7**(9):405-410. DOI: 10.1016/ S1360-1385(02)02312-9

[52] Mittler R, Vanderauwera S, Gollery M, Van Breusegem F. Reactive oxygen gene network of plants. Trends in Plant Science. 2004;**9**(10):490-498. DOI: 10.1016/J.TPLANTS.2004.08.009

[53] Mittler R. ROS are good. Trends in Plant Science. 2017;**22**(1):11-19. DOI: 10.1016/j.tplants.2016.08.002

[54] Roy SJ, Negrão S, Tester M. Salt resistant crop plants. Current Opinion in Biotechnology. 2014;**26**:115-124. DOI: 10.1016/j.copbio.2013.12.004

[55] Mittler R et al. ROS signaling: The new wave? Trends in Plant Science. 2011;**16**(6):300-309. DOI: 10.1016/J. TPLANTS.2011.03.007

[56] Munns R, Gilliham M. Salinity tolerance of crops—What is the cost? The New Phytologist. 2015;**208**(3):668-673. DOI: 10.1111/nph.13519

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

[57] Maathuis FJM. Sodium in plants: Perception, signalling, and regulation of sodium fluxes. Journal of Experimental Botany. 2014;**65**(3):849-858. DOI: 10.1093/jxb/ert326

[58] Greenway H, Osmond CB. Salt responses of enzymes from species differing in salt tolerance. Plant Physiology. 1972;**49**(2):256-259. DOI: 10.1104/PP.49.2.256

[59] Flowers TJ, Troke PF, Yeo AR. The mechanism of salt tolerance in halophytes. Annual Review of Plant Biology. 1977;**28**(1):89-121. DOI: 10.1146/ ANNUREV.PP.28.060177.000513

[60] Shabala S et al. Xylem ionic relations and salinity tolerance in barley. The Plant Journal. 2010;**61**(5):839-853. DOI: 10.1111/j.1365-313X.2009. 04110.x

[61] Pandolfi C, Mancuso S, Shabala S. Physiology of acclimation to salinity stress in pea (*Pisum sativum*). Environmental and Experimental Botany. 2012;**84**:44-51. DOI: 10.1016/j. envexpbot.2012.04.015

[62] Kamanga RM, Echigo K, Yodoya K, Mekawy AMM, Ueda A. Salinity acclimation ameliorates salt stress in tomato (Solanum lycopersicum L.) seedlings by triggering a cascade of physiological processes in the leaves. Scientia Horticulturae (Amsterdam). 2020;**270**(April):109434. DOI: 10.1016/j. scienta.2020.109434

[63] Hasegawa PM, Bressan RA, Zhu J-K, Bohnert HJ. Plant cellular and molecular responses to high salinity. Annual Review of Plant Physiology and Plant Molecular Biology. 2000;**51**(1):463-499. DOI: 10.1146/annurev.arplant.51.1.463

[64] Gálvez FJ, Baghour M, Hao G, Cagnac O, Rodríguez-Rosales MP,

Venema K. Expression of LeNHX isoforms in response to salt stress in salt sensitive and salt tolerant tomato species. Plant Physiology and Biochemistry. 2012;**51**:109-115. DOI: 10.1016/J. PLAPHY.2011.10.012

[65] Zdravković J, Jovanovic Z, Djordjević M, Girek Z, Zdravković M, Stikic R. Application of stress susceptibility index for drought tolerance screening of tomato populations. Genetika. 2013;**45**(3):679- 689. DOI: 10.2298/GENSR1303679Z

[66] Shamim F, Saqlan SM, Athar HUR, Waheed A. Screening and selection of tomato genotypes/cultivars for drought tolerance using multivariate analysis. Pakistan Journal of Botany. 2014;**46**(4):1165-1178

[67] Negrão S, Schmöckel SM, Tester M. Evaluating physiological responses of plants to salinity stress. Annals of Botany. 2017;**119**(1):1-11. DOI: 10.1093/AOB/ MCW191

[68] Munns R et al. Avenues for increasing salt tolerance of crops, and the role of physiologically based selection traits. Progress in Plant Nutrition: Plenary Lectures of the XIV International Plant Nutrition Colloquium. 2002;**98**:93-105. DOI: 10.1007/978-94-017-2789-1\_7

[69] Fischer R, Maurer R. Drought resistance in spring wheat cultivars. I. Grain yield responses. Australian Journal of Agricultural Research. 1978;**29**(5):897. DOI: 10.1071/AR9780897

[70] E. Farshadfar and J. Sutka, Screening drought tolerance criteria in maize. 2002. Available from: https://akademiai. com/doi/pdf/10.1556/AAgr.50.2002.4.3. [Accessed: June 11, 2019]

[71] Munns R. Physiological processes limiting plant growth in saline soils:

Some dogmas and hypotheses. Plant, Cell & Environment. 1993;**16**(1):15-24. DOI: 10.1111/J.1365-3040.1993.TB00840.X

[72] Cramer GR, Bowman DC. Kinetics of maize leaf elongation I. Increased yield threshold limits short-term, steadystate elongation rates after exposure to salinity. Journal of Experimental Botany. 1991;**42**(11):1417-1426. DOI: 10.1093/ JXB/42.11.1417

[73] Neumann PM. Rapid and reversible modifications of extension capacity of cell walls in elongating maize leaf tissues responding to root addition and removal of NaCl. Plant, Cell & Environment. 1993;**16**(9):1107-1114. DOI: 10.1111/ J.1365-3040.1996.TB02068.X

[74] Yeo AR, Lee ÀS, Izard P, Boursier PJ, Flowers TJ. Short- and long-term effects of salinity on leaf growth in rice (*Oryza sativa* L.). Journal of Experimental Botany. 1991;**42**(7):881-889. DOI: 10.1093/JXB/42.7.881

[75] Passioura JB, Munns R. Rapid environmental changes that affect leaf water status induce transient surges or pauses in leaf expansion rate. Functional Plant Biology. 2000;**27**(10):941-948. DOI: 10.1071/PP99207

[76] Chazen O, Hartung W, Neumann PM. The different effects of PEG 6000 and NaCI on leaf development are associated with differential inhibition of root water transport. Plant, Cell & Environment. 1995;**18**(7):727-735. DOI: 10.1111/J.1365- 3040.1995.TB00575.X

[77] Chuamnakthong S, Nampei M, Ueda A. Characterization of Na+ exclusion mechanism in rice under saline-alkaline stress conditions. Plant Science. 2019;**287**:110171. DOI: 10.1016/J. PLANTSCI.2019.110171

[78] Pérez-Alfocea F, Estañ MT, Caro M, Guerrier G. Osmotic adjustment in

*Lycopersicon esculentum* and *L. pennellii* under NaCl and polyethylene glycol 6000 iso-osmotic stresses. Physiologia Plantarum. 1993;**87**(4):493-498. DOI: 10.1111/J.1399-3054.1993.TB02498.X

[79] Arms EM, Bloom AJ, St. Clair DA. High-resolution mapping of a major effect QTL from wild tomato *Solanum habrochaites* that influences water relations under root chilling. Theoretical and Applied Genetics. 2015;**128**(9):1713- 1724. DOI: 10.1007/S00122-015-2540-Y/ FIGURES/4

[80] Rao ES, Kadirvel P, Symonds RC, Geethanjali S, Thontadarya RN, Ebert AW. Variations in DREB1A and VP1.1 genes show association with salt tolerance traits in wild tomato (*Solanum pimpinellifolium*). PLoS One. 2015;**10**(7):e0132535. DOI: 10.1371/JOURNAL.PONE.0132535

[81] Cuartero J, Bolarín MC, Asíns MJ, Moreno V. Increasing salt tolerance in the tomato. Journal of Experimental Botany. 2006;**57**(5):1045-1058. DOI: 10.1093/jxb/ erj102

[82] Cayuela E, Perez-Alfocea F, Caro M, Bolarin MC. Priming of seeds with NaCl induces physiological changes in tomato plants grown under salt stress. Physiologia Plantarum. 1996;**96**(2):231- 236. DOI: 10.1111/j.1399-3054.1996. tb00207.x

[83] Pandolfi C, Azzarello E, Mancuso S, Shabala S. Acclimation improves salt stress tolerance in *Zea mays* plants. Journal of Plant Physiology. 2016;**201**:1-8. DOI: 10.1016/j.jplph.2016.06.010

[84] Umezawa T, Shimizu K, Kato M, Ueda T. Enhancement of salt tolerance in soybean with NaCl pretreatment. Physiologia Plantarum. 2000;**110**(1):59- 63. DOI: 10.1034/j.1399-3054. 2000.110108.x

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

[85] Djanaguiraman M, Sheeba JA, Shanker AK, Devi DD, Bangarusamy U. Rice can acclimate to lethal level of salinity by pretreatment with sublethal level of salinity through osmotic adjustment. Plant and Soil. 2006;**284**(1-2):363-373. DOI: 10.1007/ s11104-006-0043-y

[86] Kamanga RM, Oguro S, Nampei M, Ueda A. Acclimation to NaCl and H2O2 develops cross tolerance to salinealkaline stress in rice (*Oryza sativa* L.) by enhancing fe acquisition and ROS homeostasis. Soil Science and Plant Nutrition. 2021;**68**(3):342-352. DOI: 10.1080/00380768.2021.1952849

[87] Cayuela E, Estañ MT, Parra M, Caro M, Bolarin MC. NaCl pre-treatment at the seedling stage enhances fruit yield of tomato plants irrigated with salt water. Plant and Soil. 2001;**230**(2):231-238. DOI: 10.1023/A:1010380432447

[88] Tari I et al. Acclimation of tomato plants to salinity stress after a salicylic acid pre-treatment. Acta Biologica Szegediensis. 2002;**46**(46):3-455. Available from: http://www.sci.u-szeged.hu/ABS

[89] Szepesi Á et al. Role of salicylic acid pre-treatment on the acclimation of tomato plants to salt- and osmotic stress. Acta Biologica Szegediensis 2000;49(1- 2):123-125. Available from: http://abs. bibl.u-szeged.hu/index.php/abs/article/ view/2442 [Accessed: December 05, 2018]

[90] Gémes K et al. Cross-talk between salicylic acid and NaCl-generated reactive oxygen species and nitric oxide in tomato during acclimation to high salinity. Physiologia Plantarum. 2011;**142**(2):179-192. DOI: 10.1111/J. 1399-3054.2011.01461.X

[91] Szepesi A. Salicylic acid improves the acclimation of *Lycopersicon esculentum*

Mill. L. to high salinity by approximating its salt stress response to that of the wild species *L. pennellii*. Acta Biologica Szegediensis. 2006;**50**(3-4):177. Available from: http://ttkde4.sci.u-szeged.hu/ ABS/2006/ActaHPb/50177.pdf

[92] Souza AC et al. Acclimation with humic acids enhances maize and tomato tolerance to salinity. Chemical and Biological Technologies in Agriculture. 2021;**8**(1):1-13. DOI: 10.1186/ S40538-021-00239-2/FIGURES/7

[93] Ding Y, Fromm M, Avramova Z. Multiple exposures to drought 'train' transcriptional responses in Arabidopsis. Nature Communications. 2012;**3**:1-9 DOI: 10.1038/ncomms1732

[94] Ding Y, Liu N, Virlouvet L, Riethoven J-J, Fromm M, Avramova Z. Four distinct types of dehydration stress memory genes in Arabidopsis thaliana. BMC Plant Biology. 2013;**13**(1):229. DOI: 10.1186/1471-2229-13-229

[95] Murshed R, Lopez-Lauri F, Keller C, Monnet F, Sallanon H. Acclimation to drought stress enhances oxidative stress tolerance in *Solanum lycopersicum* L. fruits. Plant Stress. 2008;**2**(2):145-151

[96] Amoah JN, Ko CS, Yoon JS, Weon SY. Effect of drought acclimation on oxidative stress and transcript expression in wheat (*Triticum aestivum* L.). Journal of Plant Interactions. 2019;**14**(1):492-505. DOI: 10.1080/17429145.2019.1662098/SUPPL\_ FILE/TJPI\_A\_1662098\_SM8992.DOCX

[97] Foyer CH, Rasool B, Davey JW, Hancock RD. Cross-tolerance to biotic and abiotic stresses in plants: A focus on resistance to aphid infestation. Journal of Experimental Botany. 2016;**67**(7):2025- 2037. DOI: 10.1093/jxb

[98] Pastori GM, Foyer CH. Common components, networks, and pathways of cross-tolerance to stress. The central role of 'redox' and abscisic acidmediated controls. Plant Physiology. 2002;**129**(2):460-468. DOI: 10.1104/ pp.011021

[99] Gonzalez-Fernandez J. Tolerancia a la Salinidad en el Tomate en Estado de Plañuela y Planta Adulta—Sécheresse Info. Universidad Córdoba; 1996

[100] Balibrea ME, Parra M, Bolarín MC, Pérez-Alfocea F. PEG-osmotic treatment in tomato seedlings induces saltadaptation in adult plants. Functional Plant Biology. 1999;**26**(8):781. DOI: 10.1071/PP99092

[101] Atkinson NJ, Urwin PE. The interaction of plant biotic and abiotic stresses: From genes to the field. Journal of Experimental Botany. 2012;**63**(10):3523- 3544. DOI: 10.1093/jxb/err313

[102] Moya JL, Gómez-Cadenas A, Primo-Millo E, Talon M. Chloride absorption in salt-sensitive *Carrizo citrange* and salt-tolerant *Cleopatra mandarin* citrus rootstocks is linked to water use. Journal of Experimental Botany. 2003;**54**(383):825-833. DOI: 10.1093/JXB/ERG064

[103] Tucker DPH, Alva AK, Jackson LK, Wheaton TA. How salinity damages citrus: Osmotic effects and specific ion toxicities. HortTechnology. 2005;**15**(1):95-99. DOI: 10.21273/ HORTTECH.15.1.0095

[104] Estañ MT, Martinez-Rodriguez MM, Perez-Alfocea F, Flowers TJ, Bolarin MC. Grafting raises the salt tolerance of tomato through limiting the transport of sodium and chloride to the shoot. Journal of Experimental Botany. 2005;**56**(412):703- 712. DOI: 10.1093/JXB/ERI027

[105] Santa-Cruz A, Martinez-Rodriguez MM, Perez-Alfocea F, Romero-Aranda R, Bolarin MC.

The rootstock effect on the tomato salinity response depends on the shoot genotype. Plant Science. 2002;**162**(5):825-831. DOI: 10.1016/ S0168-9452(02)00030-4

[106] Abdeldym EA, El-Mogy MM, Abdellateaf HRL, Atia MAM. Genetic characterization, agro-morphological and physiological evaluation of grafted tomato under salinity stress conditions. Agronomy. 2020;**10**:1948. DOI: 10.3390/ AGRONOMY10121948

[107] Kokulan KS, Osumi S, Chuamnakthong S, Ueda A, Saneoka H. 8 Varietal Differences in salt Acclimation Ability of Rice (関西支部講演会, 2016 年度各支部会)2017;**63**:304-304. DOI: 10.20710/dohikouen.63.0\_304\_2

[108] Chuamnakthong S, Kokulan KS, Ueda A, Saneoka H. 9 The Effects of Mild Salinity and Osmotic Pretreatment on Salt Acclimation in Rice (関西支部講演会, 2016年度各支部会)2017;**63**:304-304. DOI: 10.20710/DOHIKOUEN.63.0\_304\_3

[109] Ma LJ et al. Pretreatment with NaCl induces tolerance of rice seedlings to subsequent Cd or Cd + NaCl stress. Biologia Plantarum. 2013;**57**(3):567-570. DOI: 10.1007/s10535-013-0310-8

[110] P. Saha, P. Chatterjee, and A. K. Biswas, "NaCl pretreatment alleviates salt stress by enhancement of antioxidant defense system and osmolyte accumulation in mungbean (Vigna radiata L. Wilczek)," 2010. Available from: http://nopr.niscair. res.in/bitstream/123456789/9073/1/ IJEB48%286%29593-600.pdf. [Accessed: June 03, 2019]

[111] Khan A et al. Silicon and salicylic acid confer high-pH stress tolerance in tomato seedlings. Scientific Reports. 2019;**9**(1). DOI: 10.1038/ s41598-019-55651-4

*Cultivation of Tomato under Dehydration and Salinity Stress: Unravelling the Physiology... DOI: http://dx.doi.org/10.5772/intechopen.108172*

[112] A. R. Gurmani et al., Exogenous Abscisic Acid (ABA) and Silicon (Si) Promote Salinity Tolerance by Reducing Sodium (Na+) Transport and Bypass Flow in Rice (*'Oryza sativa*' indica) Crop Management View Project Scope of Wetland Plants for Phyto-remediation View Project Exogenous Abscisic Acid (ABA) and Silicon (Si) Promote Salinity Tolerance by Reducing Sodium (Na+) Transport and Bypass Flow in Rice (*Oryza sativa* indica). Available from: https://www.researchgate.net/ publication/270448560. [Accessed: November 08, 2019]

[113] Sripinyowanich S et al. Exogenous ABA induces salt tolerance in indica rice (*Oryza sativa* L.): The role of OsP5CS1 and OsP5CR gene expression during salt stress. Environmental and Experimental Botany. 2013;**86**:94-105. DOI: 10.1016/j. envexpbot.2010.01.009

[114] Wei L-X et al. Priming effect of abscisic acid on alkaline stress tolerance in rice (*Oryza sativa* L.) seedlings. Plant Physiology and Biochemistry. 2015;**90**:50-57. DOI: 10.1016/J. PLAPHY.2015.03.002

[115] Wei L-X et al. Priming of rice (*Oryza sativa* L.) seedlings with abscisic acid enhances seedling survival, plant growth, and grain yield in saline-alkaline paddy fields. Field Crops Research. 2017;**203**:86-93. DOI: 10.1016/J. FCR.2016.12.024

[116] Saeidi-Sar S, Abbaspour H, Hossein AS, Yaghoobi R. Effects of ascorbic acid and gibberellin A 3 on alleviation of salt stress in common bean (*Phaseolus vulgaris* L.) seedlings. Acta Physiologiae Plantarum. 2013;**35**(3):667- 677. DOI: 10.1007/s11738-012-1107-7

[117] Li XW et al. Exogenous application of cytokinins improves grain filling of rice (*Oryza sativa* L.) in saline-alkaline paddy field. Research on Crops. 2016;**17**(4):647-651. DOI: 10.5958/2348-7542.2016.00108.X

[118] Ma X, Zhang J, Huang B. Cytokinin-mitigation of salt-induced leaf senescence in perennial ryegrass involving the activation of antioxidant systems and ionic balance. Environmental and Experimental Botany. 2016;**125**:1-11. DOI: 10.1016/j. envexpbot.2016.01.002

[119] Samea-Andabjadid S, Ghassemi-Golezani K, Nasrollahzadeh S, Najafi N. Exogenous salicylic acid and cytokinin alter sugar accumulation, antioxidants and membrane stability of faba bean. Acta Biologica Hungarica. 2018;**69**(1):86- 96. DOI: 10.1556/018.68.2018.1.7

[120] Liu L, Saneoka H. Effects of NaHCO3 acclimation on Rye (*Secale cereale*) growth under sodic-alkaline stress. Plants. 2019;**8**(9):314. DOI: 10.3390/plants8090314

[121] Wahid A, Perveen M, Gelani S, Basra SMA. Pretreatment of seed with H2O2 improves salt tolerance of wheat seedlings by alleviation of oxidative damage and expression of stress proteins. Journal of Plant Physiology. 2007;**164**(3):283-294. DOI: 10.1016/j. jplph.2006.01.005

[122] Fedina IS, Nedeva D, Çiçek N. Pre-treatment with H2O2 induces salt tolerance in barley seedlings. Biologia Plantarum. 2009;**53**(2):321-324. DOI: 10.1007/s10535-009-0058-3

[123] Gondim FA, Miranda R d S, Gomes-Filho E, Prisco JT. Enhanced salt tolerance in maize plants induced by H2O2 leaf spraying is associated with improved gas exchange rather than with non-enzymatic antioxidant system. Theoretical and Experimental Plant Physiology. 2013;**25**(4):251-260. DOI: 10.1590/s2197-00252013000400003

#### **Chapter 3**

## Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics

*Peter Amoako Ofori, Stella Owusu-Nketia, Frank Opoku-Agyemang, Desmond Agbleke and Jacqueline Naalamle Amissah*

#### **Abstract**

Greenhouse vegetable cultivation offers one of the optimistic approaches to ensuring sustainable food and nutrition security in the tropics. Although greenhouse vegetable production is known to be costly, this system of production is gaining popularity and contributes to sustainable tomato production with improved fruit quality and productivity, which results in higher economic returns. Among vegetable crops, tomato is the most cultivated under this system. A study was conducted to identify suitable soilless media for regenerating tomato cuttings from axillary stem of tomato plants and to assess the agronomic performance of the regenerated cuttings under greenhouse condition. The tomato cuttings were raised using 100% rice husk biochar, 100% rice husk, 100% cocopeat, 50% biochar +50% cocopeat, 50% cocopeat +50% rice husk. Two tomato hybrid varieties (Lebombo and Anna) were used. Cuttings from axillary stems were compared with those raised from seed. A 2 × 2 factorial experiment was arranged in a Completely Randomized Design (CRD) with four replications. From the study, 100% rice husk biochar was found to induce root development in stem cuttings of tomato. However, no significant differences in yield and fruit quality were found between plants raised from seed and those from stem cuttings.

**Keywords:** greenhouse, tomato production, food and nutrition security, tropics

#### **1. Introduction**

Tomato (*Solanum lycopersicum*) is a flowering plant belonging to the Solanaceae family, also known as Nightshade. It is one of the most popular vegetable crops grown in the world due to its fruit quality—taste, color, flavor and nutritional content [1]. Tomato fruits can be consumed in different forms; either fresh, partially cooked or processed. Tomatoes provide carotenoids, flavonoids, phytosterols, vitamins, and minerals which are essential in human nutrition. Carotenoids are the most abundant in tomatoes with the most common one being lycopene, followed

by beta-carotene, gamma-carotene, lutein, phytoene, and a few other minor carotenoids [2, 3] which have anti-cancer properties [4, 5]. It is also a great source of carbohydrates, fiber and a small amount of vitamin A, vitamin B complex (thiamin, riboflavin, and niacin) and vitamin C [6] and is also rich in iron, copper, phosphorus, manganese and potassium [7].

According to the statistical agency of the Food and Agriculture Organization of the United Nations (FAOSTAT) (2020), the world's total tomato production is estimated at 186,821 million tonnes with a cultivated area of about 5,051,983 hectares. In comparison, there has been a 3.35% increase in production from 180,766 million tonnes in 2019 to 186,821 million tonnes produced in 2020. China is the leading producer of tomatoes in the world accounting for about 34.67%. Egypt ranked fifth in global tomato production contributing 3.6% whiles leading the tomato production in Africa estimated at 6731.22 million tonnes cultivated on an area of 170.862 hectares. In addition to Egypt, other North African countries with both tropical and temperate conditions including Algeria, Tunisia and Morocco accounted for about 2.39% of the world's tomato production. Among the West African countries, the leading producers, Nigeria and Cameroun produced 3693.72 million and 1.246.65 million, respectively, whiles Kenya produced 1056.18 million to lead tomato production in East Africa [8]. In Ghana, according to the Ministry of Food and Agriculture (MoFA), tomato production is estimated at 420,000 tonnes in 2019 cultivated on 47,000 hectares [9, 10].

The rapid increase in tomato consumption in the tropics is one of the factors influencing emerging production practices and strategies to meet local and export demands. Thus, many tropical countries have expanded their tomato acreage to meet local needs and, in some cases, to generate foreign exchange due to the increased importance of tomatoes in food and nutrition security. Several different production systems have been used successfully in different parts of the world to produce tomatoes. For instance, in the tropics, particularly in Africa, the open field cultivation system is mostly adopted whereas, in the developed countries, there is a massive shift to controlled environment systems [11]. Tomato cultivars with a determinate or semi-determinate growth habit are typically grown in open fields which are usually for fresh consumption. This system is also distinguished by the use of either direct sowing or transplanting where a nursery is established. Currently, transplanting is commonly practiced since it ensures good stand establishment, uniformity, reduced weed competition, and improved survival rate and yield compared to direct sowing [12]. Nonetheless, open-field tomato seedlings tend to be weaker and have a lower rate of transplant survival, resulting in low yields [13]. Other constraints such as biotic (high incidence of pests and diseases) and abiotic stresses (such as drought and high temperature) pose serious threats to open-field tomato production [14]. Rootknot nematodes (including *Meloidogyne incognita*, *M. javanica* and *M. arenaria*) are soil-borne pathogens that cause yield losses of about 30% in tomatoes in the tropics [5]. Thus, they cause stunted growth making the tomato plants more susceptible to soil-borne fungal (such as *Fusarium wilt* caused by *Fusarium oxysporum*) and bacterial diseases (such as bacterial wilt caused by *Ralstonia solanacearum*) [5]. Several studies on grafting techniques to combat these soil-borne root-knot nematodes and fungal diseases have resulted in the identification of potential rootstocks such as *Solanum torvum*, *Solanum macrocarpon*, and *Solanum aethiopicum* [15] that confer tolerance to these soil-borne problems. However, due to the high cost of producing grafted seedlings in large quantities, grafting is not widely used in large-scale production in the tropics [16]. Furthermore, open-field tomato cultivation exposes the plants to a

#### *DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*

variety of stinging and sucking insects, such as whitefly, thrips, and aphids, which cause moderate to severe physical damage as well as contribute to the transmission of viruses [5]. High temperatures observed in open-field tomato production in the tropics cause heat stress [17]. Tomato is an extremely sensitive crop to heat stress, which can lead to total yield loss [18]. A slight increase in night temperature especially can decrease pollen viability and female fertility thereby impairing fruit set and consequently yield reduction [19].

Increased tomato consumption [20] combined with unfavorable climatic conditions necessitates the development of urgent strategies to boost production whiles improving fruit quality in the tropics. Open field tomato production is hampered by climate change-related factors such as high temperatures, drought and high incidence of pests and diseases. In recent years, greenhouse tomato farming has proven to be the most efficient method of producing high-quality fresh tomatoes for both domestic and international markets [1]. In addition, it provides the opportunity for year-round production. Indeterminate tomato cultivars are usually used in this system, allowing the harvesting period to be extended, thereby, increasing the tomato productivity and revenue as well as improving the livelihood of farmers. This chapter discusses greenhouse structures and systems, agronomic practices, postharvest handling, prospects and challenges of greenhouse tomato production in the tropics and the use of axillary stem cuttings as an alternative method of producing true-to-type tomato seedlings for cultivation.

#### **2. Greenhouse structures**

Greenhouse farming systems have been adopted in some African countries, especially in Northern Africa (Algeria, Egypt, Morocco, and Tunisia), Eastern Africa (Kenya, Ethiopia, Uganda, and Rwanda), Western Africa (Ghana) and South Africa. In Northern Africa, the greenhouse system is mainly used for vegetable production whiles that of Eastern Africa (for e.g., Kenya), is for flower production. Furthermore, in Rwanda, South Africa and Ghana greenhouse system is mainly used for tomato production [21]. In all these countries, the greenhouse specifications are dependent on the availability of construction inputs, local climatic conditions and socio-economic status [11]. Generally, the initial investment cost of greenhouse construction is very high. Galvanized metals including steel or aluminum are the preferred construction material as they are durable and require less amount of material for construction thereby increasing light transmission (**Figure 1**). Wood such as bamboo is an alternative material (**Figure 2**). Though it is less expensive, more wooden materials are required to ensure a solid and firm structure. This, however, reduces light transmission. Also, the cost of maintenance in using bamboo is relatively higher compared to those constructed from metals [21].

High sidewalls in greenhouse construction are critical for maximizing the effectiveness of natural ventilation in greenhouses with roof venting. The direct/diffuse ratio in incident light, as well as the diffusion properties of covering materials [22, 23], greenhouse design, time of day, season, and location, all influence light transmission and spatial uniformity of light intensity inside the greenhouse [11]. To promote plant growth and development, an ideal greenhouse ensures that light is evenly distributed. Again, to ensure optimal light transmission in the greenhouse, the type of covering material should be considered. These include; (1) a non-waterproof net which provides partial shade and protection against insect permeability; (2) a plastic film

#### **Figure 1.**

*Greenhouse of West Africa Center for Crop Improvement (WACCI), University of Ghana built from galvanized metals including steel or aluminum.*

#### **Figure 2.**

*Greenhouse of Institute of Applied Science and Technology (IAST), University of Ghana built from bamboo.*

for protection against insects and rains and (3) a glass which is more durable and effective than plastic films. Glass is mostly used for high-tech greenhouses [21]. In most greenhouses in Africa, side nets are fixed to provide natural ventilation (**Figure 3**). Circulation fans (chimney) (**Figure 4**), misting/fogging and hosing (**Figure 5**) can also be used to regulate/manage the climatic conditions in the greenhouse. In addition, shade screens/nets are also used to reduce the intensity of solar radiation in the greenhouse (**Figure 5**) [21].

#### **2.1 Greenhouse agronomic practices**

Good greenhouse crop management practices serve as a gateway for ensuring sustainable production, increasing yield and high fruit quality, concomitant with increased income generation. Before plant establishment; raising vigorous and healthy seedlings, greenhouse fumigation media selection and sterilization, fertigation and irrigation, etc. need to be considered. In addition, other recommended

*DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*

**Figure 3.** *Fixing of side nets (indicated with the arrow) to provide natural ventilation.*

#### **Figure 4.**

*Circulation fans (chimney) are fixed on greenhouses of IAST to regulate the climatic conditions in the greenhouse.*

#### **Figure 5.**

*Misting/fogging and hosing (blue arrow) are used to regulate the climatic conditions as well a shade net (red arrow) is used to reduce the intensity of solar radiations in the greenhouse.*

greenhouse cultural practices such as plant spacing, pruning, topping, training/trellising and hormone application and pollination should be performed.

#### **2.2 Tomato varieties and propagation**

The cultivation of tomatoes in the tropics is solely by using seeds; either openpollinated (OPV) or hybrids. Hybrid seeds of tomatoes are the most suitable planting materials because of their vigor and high yielding potential [24]. Since greenhouse cultivation is done in a limited area, indeterminate hybrid tomato varieties are cultivated [11]. For instance, in Ghana, hybrid tomatoes such as Cobra, Anna F1, Lebombo, Kwando, Jaguar, Gamharr, Jarrah, Eva, Ranja, and Sodaja are being introduced by seed companies for greenhouse cultivation. Several greenhouse screenings and evaluations of exotic tomato lines are being carried out to identify adaptable high yielding types with excellent fruit quality. However, cultivating these hybrid tomatoes in the tropics could be very expensive and as such, vegetative propagation of tomatoes could be a viable option for producing true-to-type tomato hybrid planting materials [25] to ensure sustainable production.

A study was conducted to identify a suitable soilless medium for regenerating tomato seedlings from axillary stem cuttings and to assess the agronomic performance of the regenerated seedlings under greenhouse condition. Cuttings (12–15 cm long) from mature tomato plants were taken and raised using 100% rice husk biochar, 100% rice husk, 100% cocopeat, 50% biochar + 50% cocopeat, 50% cocopeat + 50% rice husk. A 2 × 2 factorial experiment arranged in a Completely Randomized Design (CRD) with four (4) replications was used. Treatments consisted of two factors; two tomato hybrid varieties (Lebombo and Anna) and planting materials (cuttings and seeds). Seedlings were also raised using 100% rice husk biochar. Seedlings and rooted cuttings were sown and transplanted 28 days respectively into pots (22 × 25 cm) half filled with 100% cocopeat. The study identified rice husk biochar (**Table 1**) as a suitable medium for generating vigorous and healthy tomato stem cuttings obtained from pruned axillary shoots of tomato varieties, Lebombo and Anna F1 (**Figure 6**). Further evaluation using tomato plants generated from seeds and stem cuttings indicated that there were no significant differences in yield (**Table 2**) and fruit quality (**Table 3**). Hence, vegetative propagation via axillary stem cuttings could be used as an alternative method of raising tomato seedlings in the tropics. Seed companies and tomato nursery production operators can collaborate to leverage this method to supply tomato seedlings at affordable rates to ensure sustainable greenhouse tomato production in the tropics.

#### **2.3 Substrate and sterilization**

Plant roots are contained within a porous rooting medium called a 'substrate' or 'growing medium.' A suitable growing medium is required to provide root anchorage and a favorable environment for healthy root development, [26]. Growing media for greenhouse cultivation in the tropics comes in two basic types: soil- and organicbased. Field soil is the main component of the soil-based media and is the most simple and cheapest. However, it is associated with a high risk of soil-borne diseases such as bacterial wilt [21]. On the other hand, organic materials such as composted waste, peat, coconut peat/coir, sawdust, wood and bark are used to prepare the organic-based media [27]. Peat moss, vermiculite, and perlite which are premixed blends of organic and inorganic materials are commercially available. These products, however, are costly and difficult to obtain locally in the tropics, especially in Africa. Agricultural

*DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*


#### **Table 1.**

*Mean Root length, Survival plants per replication, Root volume, shoot dry weight, root dry weight and Total dry weight. Means followed by the same letters within a column are not significantly different according to Fisher's Protected LSD at 5%.*

and municipal wastes, which are locally available, affordable, and environmentally sustainable, should be investigated as alternatives to commercial products in the tropics. A good soil-free substrate should have excellent chemical, biological and physical characteristics with low nutrient content, low pH, a unique combination of high-water retention capacity, high air space, lightweight, pest, and disease-free [28]. Cocopeat, a waste product obtained from the mesocarp of coconut (*Cocos nucifera*) fruit is most widely used in Africa and Asian countries such as the Philippines, Indonesia, India and Sri Lanka, where lots of coconuts are produced [28]. It can be combined with rice husk biochar and oyster shells. Although cocopeat is a better substitute for peat moss, high levels of natural soluble salts, sodium, and chloride are present and could cause osmotic stress to plants. As a result, to make these materials suitable for crop production, they are buffered or flushed out to remove excessive salts [29]. Sterilization of growing media is required before use, especially the locally prepared ones to prevent the introduction of pathogens and weeds in the greenhouse. Heat sterilization is the most common method (**Figure 7**). Although the most popular and cheapest method is solar sterilization, other improvised systems have been developed. Regardless of the system, it is critical to ensure that the entire media is exposed to uniform and adequate heat for efficient and effective sterilization [27].

#### **2.4 Plant spacing and density**

Due to the high cost of greenhouse infrastructure, increasing plant density is one strategy for maximizing the limited space [30]. However, it is also important to

**Figure 6.** *Lebombo (A) and Anna (B) tomato seedlings raised from stem cuttings.*


**Table 2.**

*Days to 50% flowering and fruiting, the total number of fruits, number of fruits per plant, fruit weight per plant, yield and shelf life of tomato plants. Means followed by the same letters within a column are not significantly different according to Fisher's Protected LSD at 5%.*

plant in rows at a recommended spacing (**Figure 8**) to achieve an optimum yield. The required spacing between tomato plants will ensure an even distribution of resources such as water, nutrients, light, and air [31]. For example, there is more competition for light due to the overlapping and shading of leaves when plants are closely spaced [32]. The amount of light intercepted by the basal leaves could be drastically reduced, lowering the plants' photosynthetic efficiency. Consequently, the plants may be


*Fruit girth, Fruit length, Brix, Firmness, Pericarp thickness, Juice volume, pH and Titratable acidity of tomato fruits. Means followed by the same letters within a column are not* 

*significantly different according to Fisher's Protected LSD at 5%.*

*DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*

**49**

**Figure 7.** *Dry heat from a flame used for the sterilization of growing media.*

**Figure 8.** *Tomato plants planted in rows at a recommended spacing.*

forced to trade off their energy for stem elongation and reduced assimilate transport to developing fruits [31], thereby, causing yield reduction and poor fruit quality [33]. There have been reports of great increases in tomato yield and yield components when recommended plant spacing was used [33–35]. A recent study by Nkansah et al. [36] suggested plant spacing of 0.2 × 1.3 m for greenhouse tomato production.

#### **2.5 Irrigation and fertigation**

Adequate water supply to plants is essential for various metabolic and physiological processes such as photosynthesis, nutrient transport, and cell expansion and development [27]. In the tropics, water for greenhouse production can be obtained from rivers, ponds or reservoirs, rain, groundwater (boreholes), and municipal sources (tap water). Unfortunately, water quantity, quality and seasonal availability are not guaranteed in most tropical environments. A good water should be free from pests (such as pathogenic bacteria, fungi, weeds and pesticide contamination) and high concentrations of dissolved salts and toxic ions (heavy metals) [27]. As a result, a thorough biological and chemical analysis of water for greenhouse tomato production

*DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*

#### **Figure 9.**

*Water tanks are elevated above the level of the field to allow for the natural flow of water and nutrients.*

#### **Figure 10.**

*Water and nutrients are applied using a computerized system with sensors and a pre-programmed fertigation regime.*

is required as this can affect plant health, growth and development. The chemical property, for instance, is useful for the formulation of nutrient solutions.

In the tropics, the manual irrigation system is the cheapest but does not give precision in terms of the quantity of water and nutrients applied. Gravitational fertigation in combination with drip irrigation is the commonly adopted method. The water tank is elevated (**Figure 9**) to allow water and nutrients to flow naturally [37]. Water and nutrients can be reused by using a recirculation system [11]. Water recirculation, on the other hand, increases the risk of spreading soil-borne diseases, necessitating the use of a disinfection unit (UV or heat treatment) [38] which can be costly. Another means of supplying water and nutrients is using a computerized system with sensors and a pre-programmed fertigation regime (**Figure 10**). This system, however, is reliant on a constant supply of electricity, which is a major challenge in the tropics [21].

#### **2.6 Pruning, topping and training/trellising**

Tomato cultivars are divided into two categories based on their growth habits: determinate and indeterminate. Determinate tomatoes grow in a bush-like manner,

**Figure 11.** *Pruning of tomato vines by removing the stem suckers.*

reaching a fixed mature size characterized by synchronized flower formation and fruit production. On the other hand, indeterminate tomatoes grow in a vine-like manner, continuing to grow throughout the growing season and thus, having continuous flower and fruit formation [39]. The indeterminate tomato cultivars are used in greenhouse tomato cultivation [11]. Tomato vines are pruned by removing the stem suckers (**Figure 11**). These are stem branches or side shoots that emerge from the leaf axils which are the junctions between the main stem and the true leaf. If not pruned, these suckers will grow into full shoots with leaves, flowers, and fruits, and even regenerate new suckers. When suckers are young and small, they can be pinched or cut using pruners such as knives, scissors and secateurs. In any of these pruning approaches, it is better to ensure decontamination either by using an alcohol-based sanitizer or washing with soap to prevent the spread of pathogens [40]. Pruning can be done on weekly basis to improve or ensure efficient air circulation/aeration [41]. In addition, pruning helps to prevent the diversion of assimilates from the developing fruits thereby, improving tomato fruit quality [40, 42].

Another important greenhouse technique is topping (**Figure 12**), which involves cutting or pinching off the terminal bud to break the apical dominance [43]. This technique is critical because tomato cultivars for greenhouse cultivation are indeterminate types characterized by indefinite growth. Topping has been shown to improve fruit quality and yield by causing assimilates to be redistributed to developing fruits [44, 45]. In the Solanaceae family, topping improved yield and yield components in eggplant [46], pepper [47] and tomato [36]. According to Nkansah et al. [36], tomato yields were increased by topping at truss 2.

The main stem of tomato plants is positioned upright immediately after transplanting to keep the leaves and fruits from touching the ground [48], facilitate pollination, maximize light interception of the younger leaves, and increase labor efficiency in pruning and harvesting [11]. This method known as stem training/trellising (**Figure 13**) is necessary for indeterminate tomato cultivars. It entails securing the main stem with a twine/rope suspended from a horizontal wire about 2.5–3.2 m above the ground [11, 49]. Non-slip loops or clips are used to secure the twine's tip

*DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*

**Figure 12.** *Topping tomato plants by cutting or pinching off the terminal bud.*

#### **Figure 13.**

*Trellising or training of tomato plants by securing the main stem with a twine/rope suspended above the ground.*

to the stem's base. The twine is then neatly wound in two or three spirals around the stem for each truss without damaging the stem [11].

#### **2.7 Hormone application and pollination**

Heat stress is a major problem hampering tomato production in the tropics [50]. Poor fruit set occurs in greenhouse systems where the microenvironment is not fully controlled or automated. Tomato is an extremely sensitive crop to heat stress, which can lead to total yield loss. The optimal day and night temperatures for tomato production are 21–29.5°C and 18.5–21°C, respectively. However, a slight increase in night temperature especially can decrease pollen viability and female fertility thereby impairing fruit set and consequently yield reduction [19]. Pollination and fertilization must both be completed before the fruit set can occur (**Figure 14**) [51]. Under heat stress, however, these processes are disrupted, resulting in flower abortion and flower drop [50]. Unfortunately, the molecular mechanisms underlying tomato fruit set are unknown, despite the fact that exogenous application of auxin and gibberellin to the

**Figure 14.** *Pollination and fertilization of tomato flowers before fruit set.*

tomato stigma improved tomato fruit set. Bypassing pollination and fertilization, auxin or gibberellin can stimulate tomato fruit development (cell division and expansion) [51]. As a result, using these hormones can help increase greenhouse tomato production by increasing fruit set and yield [52]. The coordinated mechanism of auxin, gibberellin, and cytokinin has been investigated for the development of parthenocarpic tomato fruits [53], which improves fruit quality. Although this may be labor intensive, the high returns from increased productivity and improved fruit quality can compensate for this.

#### **2.8 Greenhouse pest and disease management**

One of the reasons for the rise in greenhouse tomato production in the tropics is the benefit of reducing pest and disease outbreaks, which can affect plant growth and development, resulting in lower yields and poor fruit quality. To control pest or disease outbreaks, an integrated pest management approach including cultural, biological and chemical measures (**Figure 15**) is used. Because prevention is the best approach, ensuring good environmental practices is an important first step [54]. Regular cleaning and washing of the greenhouse and its equipment with disinfectant (such as bleach) and fumigation prior to the start of the production cycle are examples of best practices. Another strategy is to keep a close eye on the crops in the greenhouse in case of a pest or disease outbreak [55]. Pheromone traps

*DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*

#### **Figure 15.**

*Chemical application for the management of pest and disease in greenhouse vegetable production.*

#### **Figure 16.**

*Pheromone traps (A) and sticky cards (B) are used to trap, detect, and determine pest population thresholds in greenhouses.*

and sticky cards (**Figure 16**), for example, are used to trap, detect, and determine pest population thresholds of pests such as leaf miners, whiteflies aphids and thrips [8, 55]. A comprehensive pest management guide for tomato production is available [8]. Pruning, trellising, and proper plant density and spacing ensure good aeration. Avoidance of wet floors by preventing irrigation water spillage helps to reduce the creation of a microclimate that promotes disease outbreaks [55].

#### **2.9 Harvesting and postharvest handling**

Harvesting of greenhouse tomatoes is usually done at the breaker of color or when the fruit is orange-red, by handpicking. Thus, greenhouse tomatoes are typically

harvested riper than fresh market field-grown fruit, making them more susceptible to mechanical injuries due to their softer nature and shorter shelf life than mature-green fruit. Greenhouse-grown fruit harvesting is done twice or three times per week as it reaches the appropriate stage of fruit development [11]. Prior to temporary storage, tomato fruits are sorted and graded. Grading allows a grower to serve different qualities at different prices to different markets, such as a supermarket and a wet market. As such, good packaging is required to reduce losses during transportation [21]. Harvested tomato fruits are chilling sensitive. Breaker fruits can be stored at 10–12.5°C for a week whiles orange-red at 7–10°C for 3–5 days [11]. Even though greenhouse tomatoes are more expensive than field-grown fruits, they are primarily produced for local consumption in the tropics. On the other hand, Northern African countries (such as Egypt and Morocco) and South Africa, produce greenhouse tomatoes for export to Europe [21].

#### **3. Prospects and challenges of greenhouse tomato production in the tropics**

#### **3.1 Prospects**

In the tropics, greenhouse tomato production has the potential to create attractive jobs for youth and women in particular [56]. Greenhouse training programs have been introduced in West Africa, particularly in Ghana, to target entrepreneurs and young graduates to learn how to grow vegetables in greenhouses [57].

The increased demand for greenhouse tomatoes, owing to their superior fruit quality, benefits growers by earning appreciable income to improve their livelihoods [58]. People in urban and peri-urban cities have gradually accepted and are willing to pay more for greenhouse tomatoes, despite the fact they are more expensive than those grown in the field [59].

Greenhouse tomato production supplements local tomato production, which is primarily a field-grown system that is affected by biotic and abiotic factors. Thus, the introduction of greenhouses in the topics has helped to ensure year-round tomato production and supply of high-quality fruits, ensuring sustainable food and nutrition security [60]. Also, there will be a constant supply of tomatoes to the processing industries for various industrial activities.

In addition, the greenhouse tomato production system contributes to the economic maximization of limited land and other resources [61]. This system, for example, ensures efficient water and nutrient supply to the plants while reducing losses such as leaching, which is common in field-grown systems. Also, unproductive lands, rooftops and concreted areas can be utilized for greenhouse tomato cultivation [62].

Another advantage of greenhouse tomato production is the complete control over indiscriminate agrochemical (pesticides, fungicides and weedicides) application. Strict adherence to greenhouse agronomic practices and integrated pest management systems eliminates traces of these agrochemicals on tomato fruits, which are harmful to human health [58]. This could promote the use of traceability systems to encourage the export of greenhouse tomato fruits in order to generate foreign exchange to boost tropical economies [63].

The introduction of greenhouses has opened up new areas in the tropics for academic and research work. To improve greenhouse tomato cultivation in the tropics, researchers should look into areas such as greenhouse agronomic practices, breeding *DOI: http://dx.doi.org/10.5772/intechopen.105853 Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics*

for tropics-adapted greenhouse tomatoes, commercial adoption of grafting techniques for soil-based greenhouse cultivation, development of tropical soilless media and nutrient solutions, assessment and availability of raw materials for greenhouse constructions and so on.

#### **3.2 Challenges**

The initial cost of constructing a greenhouse is high which deters average income entrepreneurs to venture into greenhouse tomato production [64]. In addition to this, accessibility to credit facilities is difficult [65]. Lack of greenhouse technical know-how has also hindered the adoption of greenhouse tomato production in most tropical countries. In some areas, there are no greenhouse training centers for handson training to fully equip trainees in greenhouse design, construction, repair and maintenance and cultivation [66].

The unavailability of adaptable greenhouse tomato cultivation possess a major challenge. There is a high influx of imported tomato hybrids into various countries, however, some of these tomato hybrids are not adequately evaluated or screened to identify the promising candidates for further evaluations and official release. In addition, the available tomato hybrids are generally expensive for the local growers and may have fruit quality characteristics which are not preferred by the local market [45].

There is also a lack of greenhouse cultivation inputs and important resources. For instance, poor water quality and quantity prevent seasonal and year-round greenhouse tomato cultivation. Also, the unavailability of quality soilless substrates is a major challenge [58].

#### **4. Conclusions**

In conclusion, greenhouse tomato production is a promising technology that can ensure sustainable food and nutrition security in Africa. The selection of the proper greenhouse structure and system as well as the adoption of the appropriate agronomic practices and postharvest handling techniques would ensure enhanced tomato production under greenhouse condition in the tropics. Our research findings point to tomato cuttings as a viable source for raising planting material for tomato cultivation in the developing countries. The yields and fruit quality obtained from the use of seedlings versus stem cuttings were comparable.

It is therefore essential to encourage scientific research about greenhouse production in Africa to foster its adoption. Greenhouse tomato production has the potential of creating jobs and increasing income generation thereby improving the livelihood of the people in the greenhouse tomato value chain.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Author details**

Peter Amoako Ofori1 , Stella Owusu-Nketia<sup>2</sup> , Frank Opoku-Agyemang2 , Desmond Agbleke2 and Jacqueline Naalamle Amissah2 \*

1 Institute of Applied Science and Technology College of Basic and Applied Sciences, University of Ghana, Accra, Ghana

2 Department of Crop Science, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana

\*Address all correspondence to: jnamissah@ug.edu.gh

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics DOI: http://dx.doi.org/10.5772/intechopen.105853*

#### **References**

[1] Nicola S, Tibaldi G, Fontana E, Crops A-V, Plants A. Tomato production systems and their application to the tropics. Acta Horticulturae. 2009;**821**:27-34

[2] Beecher GR. Nutrient content of tomatoes and tomato products. Proceedings of the Society for Experimental Biology and Medicine. 1998;**218**:98-100

[3] Chaudhary P, Sharma A, Singh B, Nagpal AK. Bioactivities of phytochemicals present in tomato. Journal of Food Science and Technology. 2018;**55**:2833-2849

[4] Miller EC, Hadley CW, Schwartz SJ, Erdman JW, Boileau TW-M, Clinton SK. Lycopene, tomato products, and prostate cancer prevention. Have we established causality? Pure and Applied Chemistry. 2002;**74**:1435-1441

[5] Naika S, Van Lidt de Jeude J, de Goffau M, Hilmi M, Van Dam B. Cultivation of tomato. Production, processing and marketing. In: Dam BV, editor. Digigrafi; 2005

[6] Sainju UM, Dris R. Sustainable production of tomato. Europe. 2006;**703**(26):27

[7] Ivanova N, Khomich L, Beketova N. Tomato juice nutritional profile. Voprosy Pitaniia. 2018;**87**:53-64

[8] Hortoinfo. Worldwide tomato production exceeds 186,800 million kilos. Available online: [Accessed: April 19]

[9] MoFA. Annual Crop Estimates. Statistics, Research, and Information Directorate. Accra: Ministry of Food and Agriculture (MoFA); 2020

[10] IFPRI. Ghana's Tomato Market. MoFA-IFPRI market Brief No. 3 (April 2020), Accra, Ghana. Accra: International Food Policy Research Institute (IFPRI); 2020

[11] Heuvelink E. Tomatoes. Vol. 27. CABI; 2018. ISBN: 9781780641935

[12] Barrett D. Future innovations in tomato processing. In: Proceedings of the XIII International Symposium on Processing Tomato. Vol. 1081. ISHS Acta Horticulturae; 2014. pp. 49-55

[13] Siam G, Abdelhakim T. Analysis of the Tomato Value Chain in Egypt and Establishment of an Action Plan to Increase its Efficiency (Doctoral dissertation). Montpellier: CIHEAM-IAMM; 2018

[14] Melomey LD, Ayenan MA, Marechera G, Abu P, Danquah A, Tarus D, et al. Pre- and post-harvest practices and varietal preferences of tomato in Ghana. Sustainability. 2022;**14**:1436

[15] Okorley BA, Agyeman C, Amissah N, Nyaku ST. Screening selected solanum plants as potential rootstocks for the management of root-knot nematodes (Meloidogyne incognita). International Journal of Agronomy. 2018;**2018**:9. Article ID 6715909. DOI: 10.1155/2018/6715909

[16] Nyaku ST, Amissah N. Grafting: An effective strategy for nematode management in tomato genotypes. In: Recent Advances in Tomato Breeding and Production. London, UK: IntechOpen; 2018

[17] Zhou R, Yu X, Ottosen C-O, Rosenqvist E, Zhao L, Wang Y, et al. Drought stress had a predominant effect over heat stress on three tomato cultivars subjected to combined stress. BMC Plant Biology. 2017;**17**:1-13

[18] Bita CE. Heat Stress Tolerance Responses in Developing Tomato Anthers (Doctoral dissertation). Netherlands: Wageningen University and Research; 2016

[19] Ayenan MAT, Danquah A, Hanson P, Ampomah-Dwamena C, Sodedji FAK, Asante IK, et al. Accelerating breeding for heat tolerance in tomato (*Solanum lycopersicum* L.): An integrated approach. Agronomy. 2019;**9**:720

[20] Branthôme, FX. Global Consumption of Tomato Products 2018/2019 Edition. Available from: https://www.aptrc. asn.au/wp-content/uploads/2020/04/ WPTC-2020-Consumption-Study.pdf [Accessed: April 17]

[21] Elings A, Hemming S, van Os EA, Campen JB, Bakker JC. The African Greenhouse: A Toolbox. Wageningen UR Greenhouse Horticulture Report GTB-1360, Glastuinbouw; 2015

[22] Hemming S, Swinkels G, Van Breugel A, Mohammadkhani V. Evaluation of diffusing properties of greenhouse covering materials. In: Proceedings of the VIII International Symposium on Light in Horticulture. Vol. 1134. ISHS Acta Horticulturae; 2016. pp. 309-316

[23] Hemming S, Mohammadkhani V, Dueck T. Diffuse greenhouse covering materials-material technology, measurements and evaluation of optical properties. In: Proceedings of the International Workshop on Greenhouse Environmental Control and Crop Production in Semi-Arid Regions. Vol. 797. ISHS Acta Horticulturae; 2008. pp. 469-475

[24] Ahmad S, Quamruzzaman A, Islam M. Estimate of heterosis in tomato (Solanum lycopersicum L.). Bangladesh. Journal of Agricultural Research. 2011;**36**:521-527

[25] Yadav D, Pal A, Singh S. Vegetative methods of plant propagation: II-grafting, cutting, layering and budding in mango. International Journal of Pure and Applied Bioscience. 2018;**6**:575-586

[26] Awang Y, Shaharom AS, Mohamad RB, Selamat A. Chemical and physical characteristics of cocopeatbased media mixtures and their effects on the growth and development of Celosia cristata. American Journal of Agricultural and Biological Sciences. 2009;**4**:63-71

[27] Wilkinson KM, Landis TD, Haase DL, Daley BF, Dumroese RK. Tropical nursery manual: A guide to starting and operating a nursery for native and traditional plants. In: Agriculture Handbook 732. Washington, DC: US Department of Agriculture, Forest Service; 2014. p. 376 732

[28] Barrett G, Alexander P, Robinson J, Bragg N. Achieving environmentally sustainable growing media for soilless plant cultivation systems–A review. Scientia Horticulturae. 2016;**212**:220-234

[29] Jeyaseeli DM, Raj SP. Chemical characteristics of coir pith as a function of its particle size to be used as soilless medium. Ecoscan. 2010;**4**:163-169

[30] Hachmann TL, Echer MdM, Dalastra GM, Vasconcelos ES, Guimarães VF. Tomato cultivation under different spacings and different levels of defoliation of basal leaves. Bragantia. 2014;**73**:399-406

[31] Mueller S, Wamser AF. Combination of planting densities with top lopping heights of tomato plants. Horticultura Brasileira. 2009;**27**:64-69

[32] Resende GMd, Costa ND. Yield and fruit quality of melon in different *Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics DOI: http://dx.doi.org/10.5772/intechopen.105853*

planting densities. Horticultura Brasileira. 2003;**21**:690-694

[33] Maboko MM, Du Plooy CP, Chiloane S. Yield of determinate tomato cultivars grown in a closed hydroponic system as affected by plant spacing. Horticultura Brasileira. 2017;**35**:258-264

[34] Balemi T. Response of tomato cultivars differing in growth habit to nitrogen and phosphorus fertilizers and spacing on vertisol in Ethiopia. Acta Agriculturae Slovenica. 2008;**91**:103-119

[35] Castoldi R, Faveri L, Souza J, Braz L, Charlo H. Productivity characteristics of endive as a function of spacing. In XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Quality-Chain Management of Fresh Vegetables: From Fork to Farm. Vol. 936. ISHS Acta Horticulturae; 2010. pp. 305-309

[36] Nkansah GO, Amoatey C, Owusu-Nketia S, Ofori PA, Opoku-Agyemang F. Influence of topping and spacing on growth, yield and fruit quality of tomato (*Solanum lycopersicum* L.) under greenhouse condition. Frontiers in Sustainable Food Systems. 2021;**5**:470

[37] Raphael O, Amodu M, Okunade D, Elemile OO, Gbadamosi A. Field evaluation of gravity-fed surface drip irrigation systems in a sloped greenhouse. International Journal of Civil Engineering and Technology (IJCIET). 2018;**9**:536-548

[38] Ehret D, Alsanius B, Wohanka W, Menzies J, Utkhede R. Disinfestation of recirculating nutrient solutions in greenhouse horticulture. Agronomie. 2001;**21**:323-339

[39] Vicente MH, Zsögön A, de Sá AFL, Ribeiro RV, Peres LE. Semi-determinate growth habit adjusts the vegetativeto-reproductive balance and increases productivity and water-use efficiency in tomato (*Solanum lycopersicum*). Journal of Plant Physiology. 2015;**177**:11-19

[40] Strader C, Johnson L. Tomato Pruning. Extension Dane County: Wisconsin Horticulture; 2021

[41] Falodun E, Ogedegbe S. Effects of pruning location on growth and fruiting of three tomato (*Lycopersicon esculentum* Mill) varieties in rainforest zone of Nigeria. Agro-Science. 2019;**18**:1-4

[42] Mourão I, Brito LM, Moura L, Ferreira ME, Costa SR. The effect of pruning systems on yield and fruit quality of grafted tomato. Horticultura Brasileira. 2017;**35**:247-251

[43] Mohammed GH, Saeid AI. Effect of topping, humic acid, mulching color and their interactions on vegetative growth and seed yield of okra. Journal of Duhok University. 2018;**20**:41-49

[44] Kinet J, Peet M. Tomato. Wallingford, Oxon: CABI; 1997. pp. 207-258

[45] Robinson EJ, Kolavalli SL. The Case of Tomato in Ghana: Productivity. Washington, D.C: International Food Policy Research Institute (IFPRI); 2010

[46] Buczkowska H. Effect of plant pruning and topping on yielding of eggplant in unheated foil tunnel. Acta Scientiarium Polonorum Hortorum Cultus. 2010;**9**:105-115

[47] Adenle-Saheed V, Oso Y, Adebanwo I, Adetayo O. Effect of Apex Removal and Different Spacing on Growth and Yield of Capsicum Frutescence. Lagos State: Polytechnic School of Agriculture; 2016. p. 65

[48] Saunyama I, Knapp M. Effect of pruning and trellising of tomatoes on red spider mite incidence and crop yield in Zimbabwe. African Crop Science Journal. 2003;**11**:269-277

[49] Ayres S. Tomato Production Guideline. Johannesburgo, Sudáfrica: Starke Ayres; 2014

[50] Sarkar M, Jahan MS, Kabir M, Kabir K, Rojoni R. Flower and fruit setting of summer tomato regulated by plant hormones. Applied Scientific Reports. 2014;**7**:117-120

[51] De Jong M, Mariani C, Vriezen WH. The role of auxin and gibberellin in tomato fruit set. Journal of Experimental Botany. 2009;**60**:1523-1532

[52] Luitel BP, Lee TJ, Kang WH. Fruit set and yield enhancement in tomato (*Lycopersicon esculentum* Mill.) using gibberellic acid and 2, 4-dichlorophenoxy acetic acid spray. Protected Horticulture and Plant Factory. 2015:27-33. DOI: 10.12791/KSBEC.2015.24.1.027

[53] Ding J, Chen B, Xia X, Mao W, Shi K, Zhou Y, et al. Cytokinin-induced parthenocarpic fruit development in tomato is partly dependent on enhanced gibberellin and auxin biosynthesis. PLoS One. 2013;**8**:e70080

[54] Melanson RA. Greenhouse Tomatoes Pest Management in Mississippi. Agricultural Communications, Mississippi State University Extension Service; 2019

[55] Centre A-I. Commercial greenhouse tomato production: Pest and disease management. 2018

[56] Njenga PK, Mugo F, Opiyo R. Youth and Women Empowerment Through Agriculture in Kenya. Kenya: VSO Jitolee Nairobi; 2011

[57] Gyimah NY. Greenhouse vegetable production; Ghana's bet to reducing vegetable importation. 2021

[58] Osei MK, Ofori PA, Adjebeng-Danquah J, Nketia SO, Frimpong-Anin K, Osei-Bonsu I, et al. Harnessing technologies for vegetable cultivation: A panacea for food and nutrition insecurity in Ghana. In: Vegetable Crops-Health Benefits and Cultivation. London, UK: IntechOpen; 2022

[59] Ackerman K. Urban agriculture: Opportunities and constraints. In: Metropolitan Sustainability. Sawston, Cambridge: Woodhead Publishing; 2012. pp. 118-146. DOI: 10.1533/9780857096463.2.118

[60] O'Sullivan C, Bonnett G, McIntyre C, Hochman Z, Wasson A. Strategies to improve the productivity, product diversity and profitability of urban agriculture. Agricultural Systems. 2019;**174**:133-144

[61] Zhang Y, Alvarez-Manzo H, Leone J, Schweig S, Zhang Y. Botanical medicines *cryptolepis sanguinolenta*, *artemisia annua*, *scutellaria baicalensis*, *polygonum cuspidatum*, and *alchornea cordifolia* demonstrate inhibitory activity against *Babesia duncani*. Frontiers in Cellular and Infection Microbiology. 2021;**11**:22

[62] Sanyé-Mengual E, Cerón-Palma I, Oliver-Solà J, Montero JI, Rieradevall J. Integrating horticulture into cities: A guide for assessing the implementation potential of rooftop greenhouses (RTGs) in industrial and logistics parks. Journal of Urban Technology. 2015;**22**:87-111

[63] Eerenstein J, Zalmijn A. Production of greenhouse vegetable crops; Principles for humid tropical areas. In: Good Agricultural Practices (GAP) for Greenhouse Vegetable Crops. SURAGRIC – 009 (COMCEC); 2015

[64] Asci S, VanSickle JJ, Cantliffe DJ. Risk in investment decision making and greenhouse tomato production

*Greenhouse Tomato Production for Sustainable Food and Nutrition Security in the Tropics DOI: http://dx.doi.org/10.5772/intechopen.105853*

expansion in Florida. International Food and Agribusiness Management Review. 2014;**17**:1-26

[65] Forkuor G, Amponsah W, Oteng-Darko P, Osei G. Safeguarding food security through large-scale adoption of agricultural production technologies: The case of greenhouse farming in Ghana. Cleaner Engineering and Technology. 2022;**6**:100384

[66] Ozor N, Nwobodo C, Baiyeri P, Enete A. Controlled environment agriculture in Africa: Benefits, challenges and the political economy. Agriculture Development. 2018;**34**:38

#### **Chapter 4**

## Principles for the Production of Tomatoes in the Greenhouse

*Olatunji Olabisi and Akeem Nofiu*

#### **Abstract**

Greenhouse technology is the technique of regulating the environmental factors for the benefit of the plant (tomato) under protective cultivation. Production of tomatoes in the greenhouse involves two stages: nursery and greenhouse. In the nursery, the plants are seeded in small cavities of the nursery tray and arranged in the nursery chamber or a small-sized tunnel where they are given maximum care. At 3–4 weeks after seeding, when they must have developed four true leaves and a well-developed root system, the seedlings are transplanted into the bigger tunnel. The transplants are given water through drip irrigation. The nutrients are supplied through fertigation in the required quantity and concentration. Pest control is done by integrated pest management system (a combination of physical, biological, and sometimes chemical control).

**Keywords:** tomato, greenhouse, fertigation, integrated pest management, environmental factors

#### **1. Introduction**

Tomato is widely cultivated for its fleshy fruits that have special nutritive value. It is the world's second-largest vegetable crop following potato, and it is the most canned vegetable. Tomato is one of the most important vegetable crops produced by farmers in Nigeria with a demand gap of 2.3 million tons [1, 2]. Tomatoes can be eaten raw or processed. It could be processed into paste, tomato ketchup, soup, juice, diced, sauce, puree, etc. It is rich in nutrients, dietary fiber, and antioxidants such as lycopene and beta-carotene that prevent cells from cancer. It has high levels of vitamin A and C and some minerals such as iron and phosphorus [3].

Tomato production in Nigeria requires serious attention as the demand for domestic and industrial use has brought about peak rates in recent times. Tomato being one of the essential staple foods rich in minerals, carbohydrates, and vitamins is an important vegetable with premium and high processing values as well as a venture with production capacity to generate employment. In an attempt to achieve food-secured status as a nation, it is therefore pertinent to improve the production of tomatoes in Nigeria. However, generally, agriculture in Sub-Saharan Africa is rainfall-dependent, which is one of the factors debilitating the production output of agricultural produce. This dependence on climate/natural environment predisposes the crop plants to lots of dangers, such as pest and disease infestation and environmental stress due to various weather extremes, resulting in poor-quality fruits and ultimately low yield.

Kaduna and Kano states, which produce 43% of national production, have a yield of 7–10 tons and sometimes 15 tons per ha [2]. So now it is imperative to emphasize the adoption and use of a protected farming system, such as screen houses and greenhouses for the production of especially high-valued or premium vegetables or crops like tomatoes. This chapter, therefore, elucidates on basic principles of greenhouse tomato production.

Greenhouse production is more expensive than producing the same crop in the open field [4]. The most important factors determining costs are depreciation of the structure and equipment, labor, energy, and variable costs such as planting material, substrate, and fertilizer.

As the term implies, principle refers to a basic idea or rule that explains or controls how something happens or works.

#### **1.1 Advantages of greenhouse tomato production**


#### **1.2 Disadvantages of greenhouse tomato production**


#### **2. Greenhouse structures**

Tomatoes can be grown in every type of greenhouse, provided it is sufficiently high to manage and train the plants vertically. Generally, greenhouses can be classified into three based on structure: wooden (which could also be bamboo) framed, pipe framed, and truss framed. The cover could be glass, plastic film, or rigid panel. The cover must have high light transmission, and importantly photosynthetically active radiation (PAR) that falls within the range of 400–700 nanometers. In the central- and north-European countries, the Venlo-type glasshouses are mostly used. They typically have 3.2, 4, 6.4, 8, 9.6, 12, 12.8, and 16 m standard spans and 5–7 m gutter height to allow high wire planting systems [5–7]. There are variations in the dimensions, structures, and coverings used in the construction of greenhouses from one country to the other. For instance, most of the greenhouse facilities used in China are unheated [8].

#### **3. Substrates and substrate systems**

There is relatively little commercial tomato production done directly in the soil, except for organic growers. In large greenhouse complexes in developed countries, 95% of greenhouse tomatoes are grown on inert artificial substrates, a system usually referred to as soilless culture. The term "hydroponic" can refer to soilless culture or to systems such as the nutrient film technique (NFT), in which no solid substrate is used and water flows almost constantly down troughs holding plant roots [9–11].

There are many types of growing systems for greenhouse tomatoes, which include NFT (nutrient film technique), PVC pipes, sand, ground culture (in the soil), troughs, rock wool slabs, and various types of aggregate media. The various aggregate media include peat moss and peat–lite mixes, perlite, rock wool aggregate, glass wool, pine bark, and so on. In a trial of growing media at the University of Arizona [8], there were no significant differences in the yield of greenhouse tomatoes between five different media (coconut coir, perlite, peat–vermiculite mixes, coir/perlite, and rock wool).

#### **4. Selection of variety**

The first step in carrying out a successful crop production is the choice of good variety. Growing a variety that is not the best choice, or using seeds that are not of the best quality, reduces your potential for success at the outset. It is smart to start with the greatest potential rather than limiting yourself by using inferior seeds, even if it saves some money. Numerous tomato varieties are being pushed into the market, but only a few are suitable for greenhouse production. For greenhouse tomato growers, indeterminate tomato varieties are recommended. In indeterminate tomatoes, the growth of the stem is continuous and this allows for continual fruit production.

The selection of the best indeterminate seed to buy should be based on the following criteria:

i. size of fruit desired.

ii.disease resistance.

iii.Lack of physiological problems, that is, cracking, cat-facing, blossom-end rot.

iv.uniformity of fruit size.

v.market demand.

#### **5. Nursery**

The success of a production cycle starts with acquiring healthy seedlings. Good healthy seedlings can be purchased from a commercial nursery. Also, the farmer can grow his seedling. Most greenhouse operators grow their seedlings. This is very desirable because it reduces the possibility of importing new diseases and insects [12]. Notwithstanding, in many other countries, seedlings are being raised successfully by special nursery farms that sell economical and high-quality seedlings to local growers

with the aid of modern technology. Transplant raising is a crucial stage in greenhouse vegetable production. The performance of a crop depends largely on the attention paid to the care given to it when it was in the nursery.

Quality seedlings are plants free from pests and diseases, quickly grown with no suppression of yield due to poor quality roots. Transplant production takes about 3 weeks, depending on temperature and light conditions. Tomato seed germinates best at 25°C, while seedling growth is optimal at 18°C night-time minimum and 27°C daily maximum. Germination rates are at least 95% and so only one seed needs to be planted per cavity. The ideal transplant size is when the seedling has four true leaves (**Figure 1**). A good seedling is as wide as it is tall and has not started flowering.

#### **5.1 Step-wise procedure for raising a nursery**

The following are the tools and materials needed for a successful nursery production: nursery tables, nursing trays, knapsack sprayer, substrate (peat moss, cocopeat, sawdust, or sterilized soil), indeterminate tomato seeds, and clean water.

**Figure 1.** *A typical tomato seedling ready for transplanting.*

#### *5.1.1 Procedure*


### **6. Transplanting**

Transplanting of tomato seedlings into the greenhouse is often carried out when they have reached the height of 7.5 cm to 10 cm [13]. The media or substrate of any type chosen requires to be thoroughly wet with water or diluted nutrient solution several hours prior to planting. The plants should be checked for any individual that fails to establish after planting. They will have to be changed. To keep the substrate moist, plants will require irrigation with diluted fertilizer solution as often as necessary. A good general rule of thumb is to maintain moisture at a level where only a few drops of water are needed to compact the soil into a clump [14].

#### **6.1 Plant population**

It is important to use the proper planting density when growing greenhouse tomatoes. Using a higher planting density will cause the yield per plant to decrease. This is basically due to plants shading each other. The costs and the amount of labor required also increase with more plants. Likewise, crowding plants tends to encourage disease proliferation because sprays cannot easily penetrate the thick foliage and foliage does not dry as readily. Plants should be arranged in double rows, about 4 feet apart in the center. Within a row, plants will average 14–16 inches between stems [15].

#### **6.2 Step-wise procedure for establishing plants in the greenhouse**

Tools and materials needed are grow bags, plastic mulch, twine, soil, sterilizing pan, cooling pan, binding wire, spade, manure, wheelbarrow, firewood, lighter, NPK 15:15:15 fertilizer, iron rod, tape rule, hammer, and drip irrigation kit.

#### *6.2.1 Procedure*


#### **7. Growth and development**

Growth and development continue in the greenhouse after transplanting (**Figure 2**). The management techniques include: Irrigation, fertigation, desuckering, staking and trellising, application of fruit-setting solution, defoliation, cleaning of filters, and flushing of driplines.

#### **7.1 Irrigation**

Large amounts of high-quality water are needed for plant transpiration, which serves both to cool the leaves and to trigger the transport of nutrients from roots to leaves and fruits. For instance, the amount of water needed by the greenhouse in the Netherlands is about 0.9 m3 /m2 /year [16]. Therefore, before building a greenhouse, it is essential to ascertain that there is adequate, quality water available all year round. EC should be <0.5 dS/m, pH from 5.4 to 6.3 and alkalinity <2 meq/l [9].

In the greenhouse, water supply is by drip irrigation (surface or sub-surface). This allows for efficient uptake of water and nutrients when mixed with fertilizer [17]. The water and nutrients are delivered to the active root zone thereby reducing nutrient loss by leaching or soil fixation. Also, the vegetative part of the plant does not come in contact with water, which reduces the growth of infection.

The frequency of irrigation varies with substrate rooting volume and its waterholding capacity. The water requirements of plants also depend on the growth stage of the plant and the season. The quantity of water required could vary from 1 to 14 l/m2 / day (0.4–5.6 l/plant/day) [4, 18, 19]. Generally, water consumption increases with the growth of the plant. The water is either gravity-fed or pumped with a mini pumping machine.

#### **7.2 Fertilizer application**

Nutrient supply to the greenhouse plants is done by nutrigation or fertigation. Nutrigation is an acronym for the two words "nutrient" and "irrigation" just as fertigation is a blend of "fertilizer" and "irrigation," hence the application of water-soluble fertilizer with the irrigation water. This allows for precision and frequency in nutrient

**Figure 2.** *Tomato plants grown directly on the soil at 2 weeks after transplanting.*

#### *Principles for the Production of Tomatoes in the Greenhouse DOI: http://dx.doi.org/10.5772/intechopen.106975*

supply, especially when the water is delivered with drip lines. Also, the nutrient is delivered to the plant even when the plant is inaccessible. The fertilizer to be applied at a particular time depends on the developmental stage of the plant and the soil test result [20], which consequently inform the design of the fertigation program. For instance, more nitrogen is supplied at the vegetative stage of the plant, while potassium is supplied during flowering and fruiting. A typical fertigation program supplies 500 g polyfeed with micronutrients (e.g., Haifa Bonus) per 1000 L water for the first 2–3 weeks after transplanting. Potassium-nitrate (e.g., Maxi K) is supplied at 2 kg/1000 L water at pH 5.6–6.5 and E.C 1.2–1.6 from week 4 after transplanting onwards, and 2 kg calciumnitrate (e.g., Haifa CalNit) at about 4 weeks after transplanting onwards. Pavani et al. [21] recommend supplying WSF 19% each of NPK at 3.75 G/M two times in a week from 21 days after transplanting, 3 g/l micro nutrient 2–3 times from 60 days after transplanting once in 30 days, and calcium nitrate 2–3 times once in 15 days.

The fertilizer is dissolved in a bucket of water before being added to the 1000 L tank full of water or supplied through a venturi system. In a venturi set-up, the fertilizer is mixed in a separate, smaller tank and a venturi injector is used to connect the fertilizer tank to the pure water pipe that goes into the greenhouse. The venturi injector operates on the principle that pressure drops accelerate the change of velocity of the water as it passes through the constriction [22].

#### *7.2.1 Fertilizer compatibility*

Two or more soluble fertilizers can be mixed in the same water and supplied to the plant provided they are compatible (**Figure 3**). For example, calcium fertilizer reacts with phosphate fertilizer to form a precipitate which blocks the emitters of the drip lines. This prevents the plants from getting water. Also, there should be no physical segregation of the components. As such it is always advisable to have two tanks in each tunnel: one aptly labeled for fertilizers that contain calcium or magnesium, and the other for those fertilizers that contain phosphorus or sulfur [24].

Where two tanks are not available, there should be a standing rule that fertilizers should not be mixed except the agronomist is present. Water-soluble fertilizers are mixed with the irrigation water depending on the fertigation program adopted.

#### **7.3 Pruning**

In greenhouse tomato production, the quality of the fruit is as important as the quantity of the yield gotten. That is, the greenhouse market prefers big, clean, and sweet fruits with higher Brix. As such, instead of allowing the growth of several branches that produces more flowers and consequently more fruits, the plant is pruned early giving fewer but bigger fruits. The tomato plants are pruned to a single stem for best production by removing all lateral shoots commonly referred to as "suckers." Suckers are the buds that emanate from the node. Usually, one sucker will form at the inner angle of the point where the leaf petiole attaches to the main stem. If the suckers are not removed, they will grow into new stems, and produce more flowers and consequently fruits. The fruits, though plenty, will be small in size and poor in quality which is not desirable for the greenhouse market. Preferably, desuckering (which is the process of removing the suckers) is carried out to maintain one main stem. The fruits, though fewer in number, will be larger, of higher quality, and command premium prices in the market. The practice of desuckering is usually done once per week, continuously, throughout the life cycle of the plant. In the process of


**Figure 3.** *Water-soluble fertilizer compatibility chart [23].* removing the suckers, one or two top-most suckers at the shoot tip are left temporarily. One of them will be retained to continue the plant growth if the terminal of the main stem breaks.

#### **7.4 Cluster thinning and fruit pruning**

The purpose of fruit pruning is to increase fruit size and fruit quality and to balance fruit load. It also helps to maintain uniformity in fruit size. Distorted or undersized fruits at the end of each cluster are removed early because they are not desirable for the market and will reduce the size of the other good fruits in the cluster. Sometimes the clusters are generally pruned to the four proximal fruits. The decision to prune the clusters depends on the cultivar, that is, what is the expected fruit size and the number of fruits usually formed on a cluster of the variety. Also growing conditions and the market size preference are other factors that determine if to prune the cluster or not.

#### **7.5 Staking and trellising**

Staking is done 2–3 weeks after transplanting. For a distance of 2.5 m between the top and bottom binding wires, the twines should be cut into lengths of 3 m each. The twine is tied to the top and bottom binding wires and wound around the stem to keep the plant standing. The twine is made taut by tying it into a loop in the middle. As the plant grows taller, the loop is adjusted and wound around the newly grown shoot.

#### **7.6 Application of fruit-setting solution**

Pollination of the female flower part must occur before the fruit will set. Whatever prevents effective pollination reduces the number of fruit set per plant. Poor pollination could result in deformed fruit, smaller fruit, and fruit that is rough along the tops. Several factors, such as extreme temperatures, high humidity, drought, toxicities, nutrient deficiencies, and lack of pollen transfer, can cause poor pollination [25]. Pollination in greenhouse tomatoes is enhanced by the use of a fruit-setting solution. This operation starts when the plant starts flowering. The solution is diluted with water at 2 ml/L inside a spray bottle and sprayed directly into the flowers one by one. This is done twice weekly.

#### **7.7 Defoliation**

Defoliation is the removal of old and lower leaves. Usually, the old lower leaves are unproductive. Removing them reduces the number of sinks and allows more nutrients to be channeled to the fruits making them bigger and more qualitative. After every harvest, all the leaves below the last fruit at the lower part of the plant are cut. The lower leaves are detached up to the first fruit ground-up. A fungicide spray (copper or mancozeb preferably) should always follow every defoliation.

#### **7.8 Cleaning of irrigation filter**

The filter attached to the tank helps to sieve dirt from the irrigation water before it gets to the drip line. It is important to clean the filter frequently so that dirt will not accumulate in the drip lines.

#### **7.9 Flushing**

Occasionally, the emitters on the drip lines get blocked due to the dirt that passes through the filter. So, the end cap of the drip lines is removed and water is released to flush out the dirt every 2 weeks.

#### **8. Environmental control**

Computers are used to control environmental factors, such as temperature, relative humidity, light intensity, and CO2 concentrations due to their capacity for automation and ease of use. They provide records of the history of the crop and its environment over time and alert operators to malfunctions in the greenhouse (greenhouse tomato production). Computers can control many mechanical devices within a greenhouse (vents, heaters, fans, evaporative pads, CO2 burners, irrigation valves, fertilizer injectors, shade cloths, and energy-saving curtains) based on preset criteria, such as temperature, irradiance, humidity, wind, and CO2 levels. Also, they can collect data from different sensors and process it. This capacity of the computer is called artificial intelligence. The computer uses the result to regulate the inner temperature or humidity of the greenhouse. The use of a computer to control the environmental factors makes it easier to balance plant growth [26–28]. Control of irrigation and fertilizer application regimes based on environmental conditions can also be computerized.

#### **8.1 Relative humidity**

In the greenhouse, humidity is a result of a precarious balance among the following: crop transpiration, soil evaporation, condensation on the greenhouse cover, and vapor escape due to ventilation. Vapor pressure deficit (VPD) affects transpiration and relative humidity. It changes as the ambient temperature changes. That is when there is low humidity and high temperature, the VPD increases resulting in increased stomatal resistance and consequently transpiration. Likewise, low VPD causes a reduction in plant transpiration that eventually results into dehydration, wilting, and necrosis [29, 30].

When the relative humidity is low, water is supplied by irrigation. However, high humidity encourages the proliferation of diseases. Generally, high relative humidity supports growth and enhances fruit setting, but if not managed, can cause water to condense on the leaf surface and lead to disease development [31].

There are limitations to the effectiveness of computers in controlling relative humidity. For example, humidity levels changes as vents are opened and closed to control temperature [32]. If the humidity goes higher than recommended and the temperatures remain at the normal level, the heating and ventilation systems should be adjusted to maintain acceptable levels of humidity and temperature. In glasshouses that have vents, the heating system should be turned on and the vents opened. In houses with fans, the fans should be turned on for a few minutes, and then the heater turned on to maintain air temperature. Venting for humidity control is most effective when the outside air is significantly cooler and drier than that inside the greenhouse. As the cool, dry air heats up in the tunnel, it absorbs the atmospheric moisture, which results in lower humidity. When the outside air is humid, venting can still be used to effectively control the relative humidity so far, the outside air is cooler than the inner air. However, practically, the cost of ventilation is justified only when the air outside is cooler and drier than the air inside.

#### **8.2 Temperature control**

The ambient temperature in the greenhouse is the primary environmental factor that affects plant vegetative growth, flower cluster development, fruit setting, fruit development, fruit ripening, and fruit quality. The average temperatures both day and night influence the growth of the crop. Higher temperature encourages faster growth [12]. Cuong and Munehiro [33] established that higher cumulative temperatures flowers bloom faster. Although maximum growth is known to occur at a day and night temperature of approximately 25°C, maximum fruit production is achieved with a night temperature of 18°C and a day temperature of 20°C (see **Table 1**). Hence, the recommended temperatures in **Table 1** are a compromise and are developed to sustain high fruit productivity while maintaining a modest crop growth all through the season. The use of a shade net is advised (where sophisticated means are not affordable) to reduce the direct impact of sunlight and heat in hot areas.

#### *8.2.1 Maintaining optimal temperatures*

Optimal day and night temperatures for different crop developmental stages are important. As temperatures increase within the range of 10–20°C, there is a direct linear relationship between increased growth and development. If daytime temperatures are warm, night-time temperatures can be allowed to fall to conserve energy as long as the mean temperature remains in the optimal range.

#### **8.3 Light**

Light is a prerequisite for plant growth. Photosynthesis, which produces plant matter, can only take in the presence of light. The chlorophyll present in the green parts of the plant, especially leaves, uses light energy to fix atmospheric carbon dioxide with water to produce carbohydrates. Generally, the rate of photosynthesis is related to light intensity [35]. The value of light in tomato production is seen when it is not adequate. At low light intensities, flower bud development is inhibited and flowers fail to set into fruits. This is because the plant is unable to produce adequate sugar and carbohydrates needed for bud, flower, and fruit formation from the low levels of radiant energy. Not only do the poor light conditions limit photosynthetic productivity but the limited carbohydrates produced during the day are expended by the respiring plant so that it can survive through the long nights [36]. Generally,


#### **Table 1.**

*Growing recommendations for tomato cropping [34].*

increased natural light intensity benefits the tomato plants, especially when adequate water, nutrients, and carbon dioxide are made available to the plant and the air temperature is prevented from becoming too high.

#### **8.4 Carbon dioxide**

As ventilation is not needed during cold weather, a carbon dioxide concentration of 1000 ppm is recommended during the day. During summer, however, when ventilation is essential, supplementing with 400 ppm carbon dioxide is economically useful in other countries [37]. Regions with a moderate (sea) climate are more likely to benefit from carbon dioxide applied in the summer, while the procedure is uneconomical in regions that have continental climates [38].

#### **8.5 Air movement**

Horizontal air movement is beneficial for several reasons. Approximately 1 m/s airspeed, which causes leaves to move slightly, is beneficial [39]. It helps to minimize the air temperature gradients across the greenhouse by blowing the moisture under the foliage and distributing it to the other parts of the greenhouse. The motion also brings down the carbon dioxide from the top of the greenhouse into the leaf canopy where it is utilized for photosynthesis and may assist in pollination [40]. Air movement improves the uniformity of the greenhouse environment and this enhances crop productivity and energy conservation.

#### **9. Pest and disease management**

Pest and disease incidence is generally low in a greenhouse farm. The ones to watch out for are bacteria wilt, nematode, *Tuta absoluta*, thrips, mites, blossom end rot (BER), and early and late blight. Control is by integrated pest management.

The soil is sterilized to reduce the spread of soil-borne diseases (bacteria wilt and nematode), while it is eliminated in soil-less culture. The most damaging tomato disease is bacteria wilt (*Rastolnia solanacearum*). When tomatoes are grown in the soil, a combination of chemical soil treatment, soil solarization, and use of tolerant varieties are used to manage the bacteria wilt [41].

Insects such as *Tuta absoluta*, locusts, and crickets are absent in glasshouses and screened out in tunnels that are covered on the sides with a net. Sticky papers are also hung in the tunnel to trap insects. IPM program is desired for pest control.

BER is a physiological disorder that results from inadequate calcium at the blossom-end of the tomato fruit. Calcium as an immobile element in the phloem needs to be managed before the deficiency symptom becomes evident [42].

#### **10. Harvest and storage of tomato fruits**

Generally, the harvesting starts about 75 days after transplanting. There are three stages of fruit ripening (**Table 2**). The market patronizing greenhouse tomatoes prefers fruits harvested at the breaker stage or pink. The fruits are carefully plucked from the plant and placed in the basket. The baskets are taken to the sorting room where they are graded according to their colors. The pink fruits are labeled Grade A, while

*Principles for the Production of Tomatoes in the Greenhouse DOI: http://dx.doi.org/10.5772/intechopen.106975*


**Table 2.**

*Stages of fruit ripening [43].*

the red ones are categorized as Grade B. Cracked tomatoes are removed and labeled Grade C after which they are all taken to the cold room where they are stored.

#### **11. Conclusions**

Tomato is a perishable vegetable fruit, which makes it difficult to preserve. Also, it is difficult to grow tomatoes in the rainy season due to the proliferation of diseases. Hence, the reason for the high market demand. Through the provision of ideal climatic conditions needed for optimal growth and possible output of any tomato variety planted, greenhouses offer a dependable alternative to growing high-quality tomatoes both in and out of season. The chapter makes it easier for a tomato farmer, an individual, or an entrepreneur who is interested in starting or expanding a tomato production firm to understand the fundamentals of greenhouse tomato production.

#### **Acknowledgement**

The authors would like to sincerely thank Ibrahim Sheikh of Dobi Agri Nig Ltd for reviewing the manuscript before it was submitted to the publishers and for the image in **Figure 2**.

#### **Author details**

Olatunji Olabisi1 \* and Akeem Nofiu<sup>2</sup>

1 El-Amin Integrated Farms Limited, Minna, Nigeria

2 International Institute of Tropical Agriculture, Ibadan, Nigeria

\*Address all correspondence to: tunjiolabisi@yahoo.com

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **References**

[1] Olaniyi JO, Akanbi WB, Adejumo TA, Akande OG. Growth, fruit yield, and nutritional quality of tomato varieties. African Journal of Food Science. 2010;**4**(6):398-402. Available from: http://www.academicjournals.org/ajfs

[2] FMARD. Tomato Action Plan for Nigeria 2015-2019. Federal Department of Agriculture, FMARD Nigeria: Horticulture Division; 2015

[3] Athar N, Spriggs TW, Taptiklis EL, Taylor GJ. The concise New Zealand Food Composition Tables. 5th ed. Christchurch: New Zealand Institute for Crop & Food Research Limited/Ministry of Health; 2001

[4] Peet MM, Welles G. In: Heuvelink E, editor. Greenhouse Tomato Production. Tomatoes: CAB International 2005; 2005. p. 259

[5] Samapika D, Barsha T, Smaranika M, Basabadatta S, Jnana P. Green-houses: Types and structural components; 2020. pp. 9-17

[6] Teitel M, Montero JI, Esteban B. Greenhouse design: Concepts and trends. Acta Horticulturae. 2012;**952**:605-620. DOI: 10.17660/ActaHortic.2012.952.77

[7] Dubey A. Chapter −5 management of environmental factors in protected cultivation. In: Research Trends in Agriculture Sciences. Vol. 17. Akinik Indian; 2020. pp. 81-110

[8] Jensen M. Controlled environment agriculture in deserts, tropics and temperate regions—A world review. Acta Horticulturae. 2002;**578**:19-25

[9] Tomatoes [PDF] [6air89m426t0]. (n.d.). Vdoc.pub. 2022. Available

from: https://vdoc.pub/documents/ tomatoes-6air89m426t0

[10] Sardare M. A review on plant without soil—Hydroponics. International Journal of Research in Engineering and Technology. 2013;**02**:299-304. DOI: 10.15623/ijret.2013.0203013

[11] Sharma N, Acharya S, Kumar K, Singh N, Chaurasia O. Hydroponics as an advanced technique for vegetable production: An overview. Journal of Soil and Water Conservation. 2019;**17**:364-371. DOI: 10.5958/2455-7145.2018.00056.5

[12] Growing Greenhouse Tomatoes in Soil and in Soilless Media | PDF | Tomato | Soil, 2022. Available from: https:// www.scribd.com/document/40516796/ Growing-Greenhouse-Tomatoes-in-Soiland-in-Soilless-Media

[13] Alvin RD. Commercial Greenhouse Tomato Production. Agricultural Extension Service: The University of Tennessee; 2015. p. 9

[14] Hochmuth GJ. Production of Greenhouse Tomatoes—Florida. Greenhouse Vegetable Production Handbook. 2012;**31**:4

[15] Snyder RG. 2016. Publication: Greenhouse Tomato Handbook. Mississippi State University Extension Service; 1828

[16] Anonymous. Kwantitatieve Informatie voor de Glastuinbouw 1995-1996. Afdeling Glasgroente en Bloemisterij, Aalsmeer/ Naaldwijk: Informatie en Kennis Centrum Landbouw; 1995

[17] Wang Y, Janz B, Engedal T, de Neergaard A. Effect of irrigation

#### *Principles for the Production of Tomatoes in the Greenhouse DOI: http://dx.doi.org/10.5772/intechopen.106975*

regimes and nitrogen rates on water use efficiency and nitrogen uptake in maize. Agricultural Water Management. 2016;**179**:271-276. DOI: 10.1016/j. agwat.2016.06.007

[18] Hanafi M, Shahidullah S, Niazuddin M, Aziz Z, Mohammud C. Crop water requirement at different growing stages of pineapple in BRIS soil. Journal of Food, Agriculture and Environment. 2010;**8**(2):914-918

[19] Pires R, Furlani P, Ribeiro R, Junior D, Sakai E, Lourenção A, et al. Irrigation frequency and substrate volume effects in the growth and yield of tomato plants under greenhouse conditions. Scientia Agricola. 2011;**68**:400-405. DOI: 10.1590/ S0103-90162011000400002

[20] Monika S, Sadhu A, Anil C, Indivar P, Shrvan K, David C. Fertigation -Modern Technique of Fertilizer Application. Vol. 52018. pp. 1062-1071

[21] Kommana P, Chinmaya J, Vani D. Cultivation Technology of Tomato in Greenhouse. 2020. DOI: 10.30954/ NDP-PCSA.2020.12

[22] Omary R et al. Review of venturi injector application technology for efficient fertigation in irrigation system. International Journal of Current Microbiology and Applied Sciences. 2020;**9**(12):46-61. DOI: 10.20546/ ijcmas.2020.901.00

[23] How to Mix Fertilizers for Foliar Feeding. Haifa Group; 2018. Available from: https:// www.haifa-group.com/articles/ how-mix-fertilizers-foliar-feeding

[24] Parewa H, Singh K, Kumar D, Beura K, Rakshit A. Knowledge of fertilizer mixing is key for improving nutrient use efficiency. International

Journal of Agricultural Enviornonment & Biotechnology. 2011;**3**(4):381-383

[25] Greenhouse Tomato Handbook— [PDF Document]. (n.d.). Fdocuments.us. 2022. Available from: https://fdocuments. us/document/greenhouse-tomatohandbook.html

[26] Yang S-F, Simbeye D. Computerized greenhouse environmental monitoring and control system based on LabWindows/CVI. Journal of Computers. 2013;**8**:399-408. DOI: 10.4304/jcp.8.2.399-408

[27] Hoshi T et al. Ubiquitous environment control system: An internet-of- things–based decentralized autonomous measurement and control system for a greenhouse environment. In: Hussmann S, editor. Automation in Agriculture—Securing Food Supplies for Future Generations. London: IntechOpen; 2017. DOI: 10.5772/ intechopen.71661

[28] Peipei W. Increase the productivity of tomato by changing the greenhouse environment. Second version. Research Skill Literature Report. 2017

[29] Körner O, Challa H. Process-based humidity control regime for greenhouse crops. Computers and Electronics in Agriculture. 2003;**39**:173-192. DOI: 10.1016/S0168-1699(03)00079-6

[30] Rabbi B, Chen Z-H, Sethuvenkatraman S. Protected cropping in warm climates: A review of humidity control and cooling methods. Energies. 2019;**12**:2737. DOI: 10.3390/ en12142737

[31] Implementation of Fuzzy Controller To Reduce Water Irrigation in Greenhouse Using Labview | PDF | Irrigation | Fuzzy Logic. (n.d.). Scribd, 2022. Available from: https://www.

scribd.com/document/187286837/ Implementation-of-Fuzzy-Controller-to-Reduce-Water-Irrigation-in-Greenhouse-Using-Labview

[32] Boulard T, Fatnassi H, Roy J-C, Lagier J, Jacques F, Nathalie S, et al. Effect of greenhouse ventilation on humidity of inside air and in leaf boundary-layer. Agricultural and Forest Meteorology. 2004;**125**:225-239. DOI: 10.1016/j. agrformet.2004.04.005

[33] Cuong DC, Munehiro T. Effects of integrated environmental factors and modelling the growth and development of tomato in greenhouse cultivation. IOP Conference Series: Earth and Environmental Science. 2019;**301**:012021. DOI: 10.1088/1755-1315/301/1/012021

[34] Biot Ontario Ministry of Agriculture, Food and Rural Affairs. Growing Greenhouse Vegetables. Toronto, Canada: OMAFRA Publication 371; 2001. pp. 116

[35] Wimalasekera R. Effect of light intensity on photosynthesis, productivity and enviromental stress. 2019:65-73. DOI: 10.1002/9781119501800.ch4

[36] Ghosh A, Dey K, Das S, Dutta P. Effect of light on flowering of fruit crops. Advances. 2016;**5**:2597-2603

[37] Easy Woodworking Plans For Beginners—Grovida Gardening. (n.d.). Www.grovida.us. 2022. Available from: https://www.grovida.us/woodworkingprojects.html

[38] Grovida F. Carbon dioxide— Growing Tomatoes. Grovida Gardening. 2016. Available from: https://www. grovida.us/growing-tomatos/carbondioxide.html/

[39] Kitaya Y, Tsuruyama J, Shibuya T, Yoshida M, Kiyota M. Effects of air current speed on gas exchange

in plant leaves and plant canopies. Advances in Space Research : the official journal of the Committee on Space Research (COSPAR). 2003;**31**:177-182. DOI: 10.1016/S0273-1177(02)00747-0

[40] Grovida F. Air movement—Growing Tomatoes. Grovida Gardening. 2020. Available from: https://www.grovida.us/ growing-tomatos/air-movement.html

[41] Fajinmi A, Fajinmi OB. An overview of bacterial wilt disease of tomato in Nigeria. Agricultural Journal. 2010;**5**: 242-247. DOI: 10.3923/aj.2010.242.247

[42] Taylor M, Locascio S. Blossomend rot: A calcium deficiency. Journal of Plant Nutrition. 2004;**27**:123-139. DOI: 10.1081/PLN-120027551

[43] Crop Guide: Tomato. Haifa Group; 2018. Available from: https://www. haifa-group.com/tomato-fertilizer/ crop-guide-tomato

Section 2
