3.2 Salinity and wheat (Triticum aestivum L.)

Wheat is a worldwide staple food belongs to the Poaceae family. Wheat ranks as the first position in grain production globally. About 36% population of the world consume Wheat as a staple food and provides carbohydrates (55%) and 20% of the food calories (20%), and protein contents (13%), which is higher than other cereals crops worldwide [58]. However, wheat production is severely affected by salinity. Wheat is susceptibility to salinity starts at 6 dS m<sup>1</sup> . Under salinity, water potential in soil lower down and Na<sup>+</sup> concentration within plant tissues increases, and as a result wheat plant faces osmotic and ionic stresses. Salinity stress having passive impacts on agronomic, physiology, and chemical characteristics of the wheat plant. As salinity level crosses the threshold level (6 dS m<sup>1</sup> ) of the wheat plant, germination rate, net photosynthesis rate, transpiration rate decrease, and yield, and increases the Na<sup>+</sup> and Cl in the wheat plant which disturbs the normal metabolism of the plant [58]. Similarly, water use efficiency (WUE), production of reactive oxygen species (ROS) and scavenging of antioxidants are attributes of the wheat plant affected by salinity.

#### 3.2.1 Salinity and agronomic attributes of wheat

Salinity stress hinders the germination rate (GR) and speed of germination, which is the vital process of the plant cycle, and an important indicator of growth

#### Salinity Stress in Arid and Semi-Arid Climates: Effects and Management in Field Crops DOI: http://dx.doi.org/10.5772/intechopen.87982

and yield components of the plant, but depend on nature of cultivar. For example, at 125–200 mM NaCl and 12.5–16 dS m<sup>1</sup> salinity levels, germination time increased and decreased the GR and germination index [59–61]. During the germination process under salinity, seed faces the osmotic stress, which imbalance the enzymatic activities necessary for nucleic acid and protein metabolism, hormonal imbalance, and ultimate the disturb the seed reserves [62]. Along with these germination characteristics, salinity also affects the other agronomic parameters such as root length, shoot length, root and shoot dry weight, plant height, leaf area, tillering dynamics, and spikes numbers per plant at the early seedling stage. At the early growth stage of the wheat plant, plant shows high sensitivity at 120, 125, 150 mM NaCl, and 16 dS m<sup>1</sup> , even seedlings death occurs [11, 63]. Furthermore, wheat seedlings also reduce its growth; even exposure to salinity stress is for a few days (7–10 days) at 100 mM NaCl salt level. Similarly, yield components such as the number of spikes per plant, spikes length, and the number of spikelets per spike, above ground biomass, 1000-grain yield, harvest index, and grain yield per plant decreased with increased salinity stress [64]. However, when the wheat plant cross the threshold level of salinity (6 dS m<sup>1</sup> ), wheat grain yield reduces at the rate of 7.1% with increasing salinity of per dS m<sup>1</sup> and significant yield reduction occurs at 15 dS m<sup>1</sup> [65].

#### 3.2.2 Salinity and wheat physiological traits

Photosynthesis activities such as net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intercellular CO2 concentration, and water use efficiency (WUE) affected by salinity. The Pn badly influenced by the high accumulation of Na<sup>+</sup> and Cl in the chloroplast tissues [66]. These parameters (Pn, Tr, Gs, intercellular CO2 concentration) are reduced under 150 mM NaCl salinity level. Similarly, a decrease in photosynthesis pigments was observed at 320 mM NaCl concertation, and after 10 days exposure of NaCl, the chlorophyll contents (chl a, b, and carotenoids) decreased [67]. WUE and RWC also affect by osmotic stress caused by salinity. Water potential lower down with increased salinity levels and as a result relative RWC in the wheat plant decreased by 3.5% in the salt tolerant cultivar and 6.7% in salt-sensitive cultivar after 6 days exposure of NaCl (100 mM NaCl) [68]. Along with this leaf water potential and WUE also decrease in 150 mM NaCl and 16 dS m<sup>1</sup> salinity levels. For example, water content percentage in root reduced and increased in shoots and spike of wheat cultivar Banysoif 1. Similarly, at 320 mM NaCl, the RWChas decreased in leaves of wheat cultivar T. monococcum seedlings [69].

#### 3.2.3 Reactive oxygen species production and scavenging of antioxidants

Reactive oxygen species (ROS) increase under salinity in the plant. However, when plant faces high salinity, the production of ROS reduces the scavenging system and stops the oxidative stress. This change occurs in plants due to the reduction of CO2 availability in leaves and inhibits fixation of carbon, and excitation energy enhance which expose the chloroplast, all these happened due to stomatal closure. ROS such as H2O2, superoxide (O2•–), hydroxyl radical (OH• ), and singlet oxygen (<sup>1</sup> O2) are produced under increasing salinity stress in the plant [62, 65]. Osmotic stress caused by salinity is the leading cause of ROS production and results in the cellular damage by oxidation of lipids, proteins, and nucleic acid. The oxidative stress is caused by an imbalance in ROS production and scavenging of antioxidants in plant tissue. As a result of ROS production, phytotoxic reactions in plants occur such as lipid peroxidation, protein degradation, as well as DNA mutation [70]. For example, exposure of salinity levels 5.4 and 10.6 dS m<sup>1</sup> for about 2

deficiencies resulting from salinity stress [49], which leads to a decrease in grain

Plant physiological traits are susceptible to the high soluble salts in its rhizosphere. Salinity has bunch of adverse effects on physiology of rice plants, such as hinder the net photosynthesis (Pn), stomatal conductance (Gs), transpiration rate (Tr), photosynthetically active radiation (PAR), degradation of pigment and relative water content (RWC) as well as affect the water use efficiency (WUE) [50]. As far as photosynthesis activity is a concern, rice plants under salinity have decreased photosynthetic efficiency through the complex of photosystem II (PSII). Furthermore, chlorophyll contents in rice leave tissues are damaged by the excessive accumulation of Na<sup>+</sup> and Cl, which hamper the primary electron transport in PSII [51]. The chlorophyll contents (chl a, b, and carotenoids) in rice leaves were significantly declined under salinity [52]. High salinity also reduces the quantum yield of the

tropic effects on rice physiology and development at the molecular and biochemical levels [53], and cause abnormal rice growth, development, and ultimately plant

Ion imbalance is the ultimate effect of salinity. Under salinity, the severe com-

Wheat is a worldwide staple food belongs to the Poaceae family. Wheat ranks as the first position in grain production globally. About 36% population of the world consume Wheat as a staple food and provides carbohydrates (55%) and 20% of the food calories (20%), and protein contents (13%), which is higher than other cereals crops worldwide [58]. However, wheat production is severely affected by salinity.

in soil lower down and Na<sup>+</sup> concentration within plant tissues increases, and as a result wheat plant faces osmotic and ionic stresses. Salinity stress having passive impacts on agronomic, physiology, and chemical characteristics of the wheat plant.

tion rate, net photosynthesis rate, transpiration rate decrease, and yield, and increases the Na<sup>+</sup> and Cl in the wheat plant which disturbs the normal metabolism of the plant [58]. Similarly, water use efficiency (WUE), production of reactive oxygen species (ROS) and scavenging of antioxidants are attributes of the wheat

Salinity stress hinders the germination rate (GR) and speed of germination, which is the vital process of the plant cycle, and an important indicator of growth

, Ca2+, and NO3

organelles [54, 55]. Similarly, boron (B), silicon (Si), and zinc (Zn) availability decreased to the rice plant, and increased cadmium (Cd) toxicity subjected to

rice root and shoot, and increases Na<sup>+</sup> and Cl, and increases Na<sup>+</sup>

concentration in the soil and plant decrease the reduce N, P, K, Ca, Mg, and Mn in

/Na<sup>+</sup> ratio. All these factors cause adverse pleio-

ratio leads to specific ion (Na<sup>+</sup> and Cl) toxicity in plant's

occurs. Generally, high NaCl

/K<sup>+</sup> and Na<sup>+</sup>

. Under salinity, water potential

) of the wheat plant, germina-

/Ca2+,

setting rate, pollen viability, and decline of the stigmatic surface.

3.1.1 Salinity and rice physiology

Climate Change and Agriculture

complex PSII, and to decrease K<sup>+</sup>

petition of Na<sup>+</sup> and Cl with K<sup>+</sup>

Ca2+/Mg2+, and Cl/NO3

plant affected by salinity.

204

salinity [56, 57].

3.1.2 Salinity and ion imbalance in rice plant

3.2 Salinity and wheat (Triticum aestivum L.)

Wheat is susceptibility to salinity starts at 6 dS m<sup>1</sup>

As salinity level crosses the threshold level (6 dS m<sup>1</sup>

3.2.1 Salinity and agronomic attributes of wheat

death [19].

months caused a significant increase in lipid peroxidation and hydrogen peroxide (H2O2) in seedlings of the wheat-sensitive cultivar [71]. Similarly, H2O2 (60%) and MDA (73%) increased at 300 mM NaCl salinity level, and decreased ascorbic acid (AsA) content (52%) in wheat seedlings [67]. For a short period salinity exposure such as after 5 days, MDA contents increased by 35%, and after 10 days, MDA contents increased by 68% at 100 mM NaCl salinity level in wheat leaves. Along with these, the concentration of salt levels in term of EC levels such as 2, 4, 8, and 16 dS m<sup>1</sup> EC effects the lipid peroxidation, MDA increased significantly and varied from cultivar to cultivar.

salt-sensitive crop, the shoot growth in maize is sharply reduced during the osmotic stress phase [76]. However, Schubert et al. [77] proved that it was cell wall extensibility, which limited the cell extension growth during osmotic stress phase than turgor in the cells. In crux, salinity-induced growth reduction in maize is primarily due to the suppressed leaf initiation and expansion, as well as internode growth and also by increased leaf abscission. Additionally, Salinity reduced the grain number and weight, leading to low grain yield of maize. This reduction was due to the limitation of the sink and reduced activity of acid inverses in developing maize

Salinity Stress in Arid and Semi-Arid Climates: Effects and Management in Field Crops

Cotton is grown as the most important fiber oilseed crop, providing 35% of the total fiber used globally [78]. About 29.5 million hectares of cotton were grown during 2016–2017 with a total production reaching to 106.49 million bales during 2017 [79] worldwide. Gossypium hirsutum is giving over 90% of the world cotton crop annually, after spreading from its origin in Mesoamerica to more than 50

Cotton is mostly grown in arid and semi-arid regions of the world, where water

[82]. Furthermore, Wang et al. [83] found that soil ECe and sodium absorption ratio (SAR) values of root zone were significantly and linearly correlated with the final germination percentage of the cotton. The FG% was adversely affected by increasing EC and SAR. These results also show that the vulnerability of cotton plants towards salinity increases with increase in plant age. Therefore, cotton plant is more sensitive to the salinity during peak flowing period, leading to less number of bolls, boll weight, and lint yield [84]. Many studies [34, 85] also reported up to 50% yield

reduction when the salinity level was increased from 7.7 to 17.0 dS m<sup>1</sup>

also induces a wide range of morpho-physiological and biochemical changes that adversely affect the cotton growth and productivity. Additionally, plant biomass accumulation and the final output are pre-determined by the rate of photosynthesis, salinity induced a direct impact on both stomatal and mesophyll conductance [86].

The production of higher fiber quality is a key objective of cotton breeding and genetics programs globally [87]. However, salinity induced lower lint percentage and fiber quality parameters, including fiber length, strength, and micronaire [84].

/K+ ratio in their tissues

. Soil salinity

shortage is a dominant factor [80]. In general, salinity severely hinders cotton growth and development, including the reduced plant height, fresh and dry weights of shoot and roots, leaf area index, node number, canopy development, photosynthesis, transpiration rate, stomatal conductance, yield, fiber quality, and root development [81]. However, cotton is considered a moderately salt tolerant crop which can withstand EC up to 7.7 dS m<sup>1</sup> [34]. Generally, salinity effects on cotton at all ontogenetical levels, from molecular to organismal, which lead towards the reduced plant growth, economic yield, and fiber quality. But these effects depend on the timing and intensity of salt stress, the plant growth stage, and the species. Therefore, seed germination and early seedling stage of cotton are considered as the most sensitive stages to salinity [1]. It has been advocated that plants having a

grains lead to poor kernel setting as well as reduced grain numbers.

3.4 Salinity and cotton (Gossypium hirsutum)

DOI: http://dx.doi.org/10.5772/intechopen.87982

countries in Northern and Southern hemispheres.

higher tolerance to salinity generally maintain lower Na<sup>+</sup>

3.4.1 Effects of salinity on cotton plant

3.4.2 Salinity and fiber quality

207

Plants also have an anti-oxidative system to compete against adverse salinity conditions. Therefore, under unfavorable conditions (salinity) plant produce antioxidant enzymes in an excessive amount such as superoxide dismutase (SOD), POD, CAT, GR, and APX, etc. which reduce the damage caused by salinity. A study showed that, under increased salinity stress, the SOD, CAT, POD, GR, ascorbic acid (AsA) and APX activities increased irrespective to the nature of wheat cultivar [68]. After 10 days of salinity stress at 100 mM of NaCl showed significant higher POD and SOD contents and non-significant increase in the CAT and APX contents with a decrease in GR and DHAR contents in wheat seedlings [67].

#### 3.2.4 Ion imbalance in wheat

Salinity stress also causes an imbalance in ion uptake and ion toxicity in the plant. Na<sup>+</sup> absorption varies from nature of wheat cultivars against salinity stress [68]. Salinity increase the intake of Na+ and Cl and reduced the K<sup>+</sup> and Ca2+ uptake along with the lower accumulation of NO3 and PO4 <sup>3</sup> in wheat seedlings under 125 mM of NaCl level for one-week exposure, and decreased the K+ /Na+ ratio in wheat shoots at 120 mM of NaCl [11, 65, 66]. Similarly at high EC 15–16 dS m<sup>1</sup> , K+ accumulation significantly decreased, and under medium salinity stress, Na+ and Cl accumulation increase and decreased the uptake of K+ , Ca2+, and Zn2+ [64, 65, 72].

#### 3.3 Salinity and maize (Zea mays L.)

Maize is an important cereal crop which is being cultivated over a large area under a wide spectrum of edaphic and climatic conditions. It is categorized as a C4 plant of the Poaceae family and is moderately sensitive to salinity [73]; nevertheless, a considerable intraspecific genetic potential against salinity also exists in the maize. The threshold level of salinity for maize is 0.25 mM NaCl or 1.8 dS m<sup>1</sup> , and a further increase in salinity may stunt growth and cause severe damages [74].

#### 3.3.1 Salinity and maize growth

Salinity significantly induces the detrimental changes in growth and development of maize, but the response of maize varies with the crop growth stage and degree of stress. The short term exposure to salinity may influence the growth of maize plants duet to osmotic stress without causing the ionic toxicity. The germination and early seedling stages of maize are more sensitive to salinity than later developmental stages. Generally, salinity during germination period delays the initiation, reduces the rate, and increases the dispersion of germination phases [75]. Salinity induces the detrimental impact on seed germination; (a) by sufficiently reducing the osmotic potential of the soil, leading to retard the water absorption by seed, and (b) by inducing Na<sup>+</sup> or Cl or both ions toxicity to the seed embryo. Therefore, hyper-osmotic effects and toxic stress of Na<sup>+</sup> and Cl ions on germinating seeds under saline conditions may delay or reduce germination [75]. Maize as a

Salinity Stress in Arid and Semi-Arid Climates: Effects and Management in Field Crops DOI: http://dx.doi.org/10.5772/intechopen.87982

salt-sensitive crop, the shoot growth in maize is sharply reduced during the osmotic stress phase [76]. However, Schubert et al. [77] proved that it was cell wall extensibility, which limited the cell extension growth during osmotic stress phase than turgor in the cells. In crux, salinity-induced growth reduction in maize is primarily due to the suppressed leaf initiation and expansion, as well as internode growth and also by increased leaf abscission. Additionally, Salinity reduced the grain number and weight, leading to low grain yield of maize. This reduction was due to the limitation of the sink and reduced activity of acid inverses in developing maize grains lead to poor kernel setting as well as reduced grain numbers.

#### 3.4 Salinity and cotton (Gossypium hirsutum)

Cotton is grown as the most important fiber oilseed crop, providing 35% of the total fiber used globally [78]. About 29.5 million hectares of cotton were grown during 2016–2017 with a total production reaching to 106.49 million bales during 2017 [79] worldwide. Gossypium hirsutum is giving over 90% of the world cotton crop annually, after spreading from its origin in Mesoamerica to more than 50 countries in Northern and Southern hemispheres.

#### 3.4.1 Effects of salinity on cotton plant

months caused a significant increase in lipid peroxidation and hydrogen peroxide (H2O2) in seedlings of the wheat-sensitive cultivar [71]. Similarly, H2O2 (60%) and MDA (73%) increased at 300 mM NaCl salinity level, and decreased ascorbic acid (AsA) content (52%) in wheat seedlings [67]. For a short period salinity exposure such as after 5 days, MDA contents increased by 35%, and after 10 days, MDA contents increased by 68% at 100 mM NaCl salinity level in wheat leaves. Along with these, the concentration of salt levels in term of EC levels such as 2, 4, 8, and 16 dS m<sup>1</sup> EC effects the lipid peroxidation, MDA increased significantly and varied

Plants also have an anti-oxidative system to compete against adverse salinity conditions. Therefore, under unfavorable conditions (salinity) plant produce antioxidant enzymes in an excessive amount such as superoxide dismutase (SOD), POD, CAT, GR, and APX, etc. which reduce the damage caused by salinity. A study showed that, under increased salinity stress, the SOD, CAT, POD, GR, ascorbic acid (AsA) and APX activities increased irrespective to the nature of wheat cultivar [68]. After 10 days of salinity stress at 100 mM of NaCl showed significant higher POD and SOD contents and non-significant increase in the CAT and APX contents with a

Salinity stress also causes an imbalance in ion uptake and ion toxicity in the plant. Na<sup>+</sup> absorption varies from nature of wheat cultivars against salinity stress [68]. Salinity increase the intake of Na+ and Cl and reduced the K<sup>+</sup> and Ca2+ uptake

wheat shoots at 120 mM of NaCl [11, 65, 66]. Similarly at high EC 15–16 dS m<sup>1</sup>

accumulation significantly decreased, and under medium salinity stress, Na+ and Cl

Maize is an important cereal crop which is being cultivated over a large area under a wide spectrum of edaphic and climatic conditions. It is categorized as a C4 plant of the Poaceae family and is moderately sensitive to salinity [73]; nevertheless, a considerable intraspecific genetic potential against salinity also exists in the maize.

Salinity significantly induces the detrimental changes in growth and development of maize, but the response of maize varies with the crop growth stage and degree of stress. The short term exposure to salinity may influence the growth of maize plants duet to osmotic stress without causing the ionic toxicity. The germination and early seedling stages of maize are more sensitive to salinity than later developmental stages. Generally, salinity during germination period delays the initiation, reduces the rate, and increases the dispersion of germination phases [75]. Salinity induces the detrimental impact on seed germination; (a) by sufficiently reducing the osmotic potential of the soil, leading to retard the water absorption by seed, and (b) by inducing Na<sup>+</sup> or Cl or both ions toxicity to the seed embryo. Therefore, hyper-osmotic effects and toxic stress of Na<sup>+</sup> and Cl ions on germinating seeds under saline conditions may delay or reduce germination [75]. Maize as a

The threshold level of salinity for maize is 0.25 mM NaCl or 1.8 dS m<sup>1</sup>

further increase in salinity may stunt growth and cause severe damages [74].

and PO4

<sup>3</sup> in wheat seedlings under

, Ca2+, and Zn2+ [64, 65, 72].

/Na+ ratio in

, and a

, K+

decrease in GR and DHAR contents in wheat seedlings [67].

125 mM of NaCl level for one-week exposure, and decreased the K+

from cultivar to cultivar.

Climate Change and Agriculture

3.2.4 Ion imbalance in wheat

along with the lower accumulation of NO3

3.3 Salinity and maize (Zea mays L.)

3.3.1 Salinity and maize growth

206

accumulation increase and decreased the uptake of K+

Cotton is mostly grown in arid and semi-arid regions of the world, where water shortage is a dominant factor [80]. In general, salinity severely hinders cotton growth and development, including the reduced plant height, fresh and dry weights of shoot and roots, leaf area index, node number, canopy development, photosynthesis, transpiration rate, stomatal conductance, yield, fiber quality, and root development [81]. However, cotton is considered a moderately salt tolerant crop which can withstand EC up to 7.7 dS m<sup>1</sup> [34]. Generally, salinity effects on cotton at all ontogenetical levels, from molecular to organismal, which lead towards the reduced plant growth, economic yield, and fiber quality. But these effects depend on the timing and intensity of salt stress, the plant growth stage, and the species. Therefore, seed germination and early seedling stage of cotton are considered as the most sensitive stages to salinity [1]. It has been advocated that plants having a higher tolerance to salinity generally maintain lower Na<sup>+</sup> /K+ ratio in their tissues [82]. Furthermore, Wang et al. [83] found that soil ECe and sodium absorption ratio (SAR) values of root zone were significantly and linearly correlated with the final germination percentage of the cotton. The FG% was adversely affected by increasing EC and SAR. These results also show that the vulnerability of cotton plants towards salinity increases with increase in plant age. Therefore, cotton plant is more sensitive to the salinity during peak flowing period, leading to less number of bolls, boll weight, and lint yield [84]. Many studies [34, 85] also reported up to 50% yield reduction when the salinity level was increased from 7.7 to 17.0 dS m<sup>1</sup> . Soil salinity also induces a wide range of morpho-physiological and biochemical changes that adversely affect the cotton growth and productivity. Additionally, plant biomass accumulation and the final output are pre-determined by the rate of photosynthesis, salinity induced a direct impact on both stomatal and mesophyll conductance [86].

#### 3.4.2 Salinity and fiber quality

The production of higher fiber quality is a key objective of cotton breeding and genetics programs globally [87]. However, salinity induced lower lint percentage and fiber quality parameters, including fiber length, strength, and micronaire [84]. However, salinity during the flowering season imposed no detrimental impacts on fiber quality, but salinity after flowering resulted in reduced fiber quality.

genotypes and kept up lower Na<sup>+</sup>

DOI: http://dx.doi.org/10.5772/intechopen.87982

varieties, Payam and Kimia [98].

3.6 Effects of salinity on sugarcane (Saccharum sp.)

being used for drinking and beverage purposes.

species which can withstand the ECe up to 1.7 dS m<sup>1</sup>

3.6.1 Salinity and sugarcane production

the nature of cultivars.

Figure 2.

209

/K+ ratios both in the root and shoot [95]. Partic-

. But, a further increase in EC

ular testimony of Na<sup>+</sup> ions in the shoot depends on leaf base [96], and enhancing levels of Ca2+ in the control condition increased plant growth and brought down Na<sup>+</sup> take-up of sorghum plants [97]. The high Ca2+ accumulation in leaf and root tissues were observed in the salt-tolerant genotype Jambo than the salt sensitive

Salinity Stress in Arid and Semi-Arid Climates: Effects and Management in Field Crops

Sugarcane is a key commercial and irrigated crop of the tropical and subtropical areas of the world [99]. Sugarcane is propagated further by setts from the stem cuttings of mature plants (one-year-old crop). Sugarcane is an important source of sugar in Asia and Europe. It also supplied the basic raw material for the production of jaggery (Gur), white sugar, and khandsari. Further, sugarcane juice is widely

The salinity is a major environmental concern, responsible for a significant decline in sugarcane yield [100]. The sugarcane production is low under less fertile soil caused by salinity stress. This plant is categorized as a moderately salt sensitive

could induce the adverse effects on its production. The detrimental impacts of salinity at germination or bud emergence stage mainly varied across the different species. Akhta et al. [101] reported a significant reduction in sprout emergence at different days after sowing under moderate and severe salinity stress depends on

Classification of field crops subjected to salinity stress. Extracted from Maas and Grattan [105].

Under severe salinity stress conditions, growth could be significantly influenced by the accumulation of active oxygen species [102]. Vasantha et al. [103] observed the reduced leaf area index (LAI) of sugarcane by 36% during Formative Growth
