**5. Cultural practices**

#### **5.1 Soil and soil amendments**

Soil types, fertilization, composts, and mulching influence the water and nutrient supply to the plant and can affect the nutritional composition, ascorbic acid content, and antioxidant activity of harvested fruit [16]. Plants grown in low-organic-matter and low-cation-exchange-capacity sandy soil amended with Ca, magnesium (Mg), and N produced more ascorbic acid in fruit than plants without supplemental fertilizer [12]. Also, Wang and Lin [16] reported that strawberry organic acids, malic acid and citric acid, were increased by the addition of fertilizer [16].

Composts have been utilized in agriculture as a significant source of organic matter. As a soil supplement, compost significantly enhances plant growth, fruit quality, and ascorbic acid and flavonoid content in strawberries. Compost causes changes in soil chemical and physical characteristics that increase beneficial microorganisms, and nutrient availability and uptake thus favoring plant growth.

**7**

*The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry*

Strawberry plants grown with compost yielded fruits with high levels of phenolics, flavonol, and anthocyanin content. The free radical absorbance capacities for peroxyl, superoxide, hydrogen peroxide, hydroxyl, and singlet oxygen in strawberries increased significantly with increasing compost use [12, 16]. Also, compost significantly increased levels of organic acids (malic and citric acid), sugars (fructose, glucose, and total sugars), soluble solids content, and TA content in "Allstar"

Strawberries grown organically showed higher levels of total phenolics compared to those produced by conventional agricultural practices, mostly because they received all required nutrients from organic matter. Also, flavonol content was higher in organically grown than in conventionally grown strawberry fruits. These data provide evidence that an improvement in the antioxidant defense system of the plant occurred as a consequence of the organic cultivation practice [12]. It has been shown that N can become a growth-limiting nutrient in organic production [39]. Strawberries need nearly neutral (6–6.5) soil pH and variation from this range affect mineral uptake and plant growth, development, yield, and fruit quality [58]. Increasing soil pH significantly reduces uptake of minerals such as iron and manganese [58, 59]. Iron deficiency has been observed in many crops when grown in high pH calcareous soils. In these soils, iron deficiency is the most important abiotic stress limiting strawberry production [60]. In fact, iron deficiency results in extensive fruit abortion with a consequent reduction of yield and fruit weight [61]. However, although most studies show a positive correlation between organic production and crop performance in strawberry, Hargreaves [59] found that organic amendments did not increase fruit quality compared to inorganic amendments, and no differences in total phenolic content were observed between conventionally and

Strawberry is commonly produced in open fields, glasshouses or plastic tunnels. Pests and diseases gradually build up in soils and limit strawberry culture. Therefore, the use of alternative substrates (soilless culture) is a common cultural method in strawberries, especially in protected environments, and has been shown

Physical and chemical properties of substrates exhibit direct and indirect effects on plant yield and fruit quality. Different substrates such as peat moss, coconut coir, perlite, rockwool, and pine bark have been used. However, peat has been the best

Cheaper alternatives to peat are being explored. For example, Zeolites (alumina silicate crystals) that have a negative charge, high cation exchange capacity, and high water holding capacity have been tested. Djedidi et al. [64] reported improved yield and quality in tomato grown in a mixture of zeolite and perlite, while Fotouhi Ghazvini [65] reported improved yield but decreased fruit quality in strawberries

An important determinant of fruit quality is the availability of essential nutrients during growth and development. Among them, calcium (Ca) slows down the ripening and senescence processes in many fruits including strawberry [66]. Nestby et al. [67] and Prange and De Ell [9] report that research conducted over the past 25 years on the effect of Ca on postharvest quality of strawberry has provided contradictory conclusions. In some studies, foliar applications and soil amendments

*DOI: http://dx.doi.org/10.5772/intechopen.84619*

and "Honeoye" strawberry cultivars [16].

organically grown strawberries.

to improve fruit yield and quality [62].

substrate for hydroponic culture [63].

**5.3 Mineral nutrition and salinity**

**5.2 Substrates**

in similar substrate.

#### *The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry DOI: http://dx.doi.org/10.5772/intechopen.84619*

Strawberry plants grown with compost yielded fruits with high levels of phenolics, flavonol, and anthocyanin content. The free radical absorbance capacities for peroxyl, superoxide, hydrogen peroxide, hydroxyl, and singlet oxygen in strawberries increased significantly with increasing compost use [12, 16]. Also, compost significantly increased levels of organic acids (malic and citric acid), sugars (fructose, glucose, and total sugars), soluble solids content, and TA content in "Allstar" and "Honeoye" strawberry cultivars [16].

Strawberries grown organically showed higher levels of total phenolics compared to those produced by conventional agricultural practices, mostly because they received all required nutrients from organic matter. Also, flavonol content was higher in organically grown than in conventionally grown strawberry fruits. These data provide evidence that an improvement in the antioxidant defense system of the plant occurred as a consequence of the organic cultivation practice [12]. It has been shown that N can become a growth-limiting nutrient in organic production [39].

Strawberries need nearly neutral (6–6.5) soil pH and variation from this range affect mineral uptake and plant growth, development, yield, and fruit quality [58]. Increasing soil pH significantly reduces uptake of minerals such as iron and manganese [58, 59]. Iron deficiency has been observed in many crops when grown in high pH calcareous soils. In these soils, iron deficiency is the most important abiotic stress limiting strawberry production [60]. In fact, iron deficiency results in extensive fruit abortion with a consequent reduction of yield and fruit weight [61].

However, although most studies show a positive correlation between organic production and crop performance in strawberry, Hargreaves [59] found that organic amendments did not increase fruit quality compared to inorganic amendments, and no differences in total phenolic content were observed between conventionally and organically grown strawberries.

#### **5.2 Substrates**

*Strawberry - Pre- and Post-Harvest Management Techniques for Higher Fruit Quality*

has direct effects on postharvest quality [50].

"Korona" remained almost constant [56].

**5. Cultural practices**

**5.1 Soil and soil amendments**

after 7 days of storage under refrigerated conditions.

levels [52].

potential impact of climate change on fruit and vegetable quality after harvest [52]. Temperature increase and the effects of greenhouse gases are among the most important issues associated with climate change. Beside rising temperatures, climate changes are also a consequence of changes in the composition of gaseous constituents in the atmosphere. Carbon dioxide accumulation in the atmosphere

The highest temperature that strawberry fruit mature normally is 35°C. At high temperatures and elevated CO2 levels, carbohydrates, such as starch and soluble sugars are degraded in the respiration process and the proteins and most minerals decrease. The nutritional quality also decreased due to more phenols and ascorbic acid. However, the effect of temperature is more pronounced than the elevated CO2

Elevated CO2 levels in storage slightly increased dehydroascorbic acid and firmness, prevented ascorbic acid reduction, and reduced anthocyanin, flavonoids, antioxidant activity and total phenolic compounds [53]. In contrast, increased CO2

resulted in increased anthocyanin and phenolic and ascorbic acid content [54]. Siriphanich [55] also reported increased firmness in strawberry treated with CO2. Cell wall analysis showed lower water-soluble pectin and higher chelating soluble pectin in CO2-treated strawberries. The mechanism of firmness enhancement by CO2 was possibly due to changes in intercellular pH and its solute composition. The influence of ozone on strawberry depends significantly on cultivar and susceptibility to oxidative stress. The effect of ozone on vitamin C content is variable in the reviewed articles and mostly cultivar dependent. In "Korona" and "Elsanta" tested by Keutgen and Pawelzik [56], ozone caused a decrease in ascorbic acid content, and lowered fruit sweetness. The ozone stress did not influence yield, size, antioxidative capacity, anthocyanins, or phenolic compounds of fruit. In the more sensitive cv. "Elsanta," ozone induced sepal injuries and fruit impairment, and a decrease in glutathione content. In contrast, fruit quality of the less sensitive cv.

In cv. "Camarosa," ozone enriched storage (0.35 μL/L) for 3 days, increased vitamin C by three times, and reduced volatile esters 40% compared to control [57]. On the other hand, Moretti et al. [50] reported that strawberries stored in atmospheres with ozone ranging from 0.3 to 0.7 μL/L showed no effect on ascorbic acid levels

Soil types, fertilization, composts, and mulching influence the water and nutrient supply to the plant and can affect the nutritional composition, ascorbic acid content, and antioxidant activity of harvested fruit [16]. Plants grown in low-organic-matter and low-cation-exchange-capacity sandy soil amended with Ca, magnesium (Mg), and N produced more ascorbic acid in fruit than plants without supplemental fertilizer [12]. Also, Wang and Lin [16] reported that strawberry organic acids, malic

Composts have been utilized in agriculture as a significant source of organic matter. As a soil supplement, compost significantly enhances plant growth, fruit quality, and ascorbic acid and flavonoid content in strawberries. Compost causes changes in soil chemical and physical characteristics that increase beneficial microorganisms, and nutrient availability and uptake thus favoring plant growth.

acid and citric acid, were increased by the addition of fertilizer [16].

above ambient)

concentrations in the growing atmosphere (300 and 600 μmolmol<sup>−</sup><sup>1</sup>

**6**

Strawberry is commonly produced in open fields, glasshouses or plastic tunnels. Pests and diseases gradually build up in soils and limit strawberry culture. Therefore, the use of alternative substrates (soilless culture) is a common cultural method in strawberries, especially in protected environments, and has been shown to improve fruit yield and quality [62].

Physical and chemical properties of substrates exhibit direct and indirect effects on plant yield and fruit quality. Different substrates such as peat moss, coconut coir, perlite, rockwool, and pine bark have been used. However, peat has been the best substrate for hydroponic culture [63].

Cheaper alternatives to peat are being explored. For example, Zeolites (alumina silicate crystals) that have a negative charge, high cation exchange capacity, and high water holding capacity have been tested. Djedidi et al. [64] reported improved yield and quality in tomato grown in a mixture of zeolite and perlite, while Fotouhi Ghazvini [65] reported improved yield but decreased fruit quality in strawberries in similar substrate.

#### **5.3 Mineral nutrition and salinity**

An important determinant of fruit quality is the availability of essential nutrients during growth and development. Among them, calcium (Ca) slows down the ripening and senescence processes in many fruits including strawberry [66]. Nestby et al. [67] and Prange and De Ell [9] report that research conducted over the past 25 years on the effect of Ca on postharvest quality of strawberry has provided contradictory conclusions. In some studies, foliar applications and soil amendments of Ca did not affect fruit quality, regardless of cultivar, yet other studies have shown increased shelf life due to Ca application [66].

Furthermore, Singh et al. [66] reported that preharvest Ca sprays greatly influenced fruit color during storage. In storage, fruit harvested from control plants turned darker whereas from the Ca spray treatment were comparatively brighter. Similarly, higher values of hue (a) and chroma (b) in such fruit indicate that fruit receiving Ca were redder and more vivid. Strawberries soften considerably during storage as a result of degradation of middle lamella, cell wall, and cortical parenchyma cells. By extension, cell wall strength, cell to cell contact and cellular turgor, which are greatly influenced by Ca may affect fruit firmness. Thus, fruits which received Ca were firmer even after 5 days of storage [66].

Calcium deficiency represents one of the most common issues for strawberry growers. Calcium plays a role in cell division and the maintenance of cell permeability and cell integrity, all of which directly influence factors such as firmness and shelf life [66]. Strawberry fruits from Ca-deficient plants are small, hard textured, acidic, seedy, or with patches covered densely with achenes, with increased deformity [17]. Calcium sprays increases fruit firmness, vitamin C and shelf life during storage [68].

However, there are reports that increasing Ca application did not affect sensory quality and decreased TA and TSS of strawberries. Calcium increased firmness and storage life up to 900 ppm. Higher concentration seems to create toxicity and imbalances of other minerals in leaf tissue.

The form of Ca applied also changes the result. Application of gypsum at planting time did not influence fruit Ca content. Therefore, cultivar, form of Ca applied, and environmental factors must be considered during Ca fertilization of strawberries [68].

Nitrogen is another important nutrient for fruit quality with both positive and negative effects of N on yield and fruit quality reported. The effect of N on fruit chemical components is inconsistent and varies from year to year, depending on time and rate of application and other environmental factors [67]. Recommended optimum concentrations of leaf N for high-yielding strawberry fields in California, North Carolina, northeastern United States, and Ontario, Canada ranges from 2.0 to 4.0%, with samples collected mostly from the leaf blade [69–73]. Form of N also affects fruit quality. Ammonium up to a ratio of 1 to 6 nitrate increased fruit firmness, but reduced red color compared to nitrate alone. Fruit vitamin C, pH, and TSS decreased with addition of ammonium up to a ratio of 1:6 (ammonium: nitrate) and then returned to the original level at the ratio of 1.5:6. Ammonium reduced TA at all concentrations [74].

Tabatabaei [40] demonstrated that both high concentrations of NO3 (100%) and NH4 (75%) has an inhibitory effect on growth of strawberry, and it becomes more pronounced in the shaded conditions.

While low concentration of ammonium improved plant growth, higher concentrations, reduced growth due to the high demand for carbohydrates for ammonium detoxification and low nitrate concentrations.

Another possible explanation is that a high concentration of NH4 reduces the uptake of cations such as Ca<sup>+</sup> and K+ and increases the concentration of NH4 + , which is toxic for the plant [40].

Higher concentration of NH4 significantly reduced postharvest life probably due to Ca deficiency in fruit. Calcium deficiency associated with NH4 nutrition can induce loss of membrane integrity which in turn may lower the concentration of potassium (K) and Mg and influence the function of chloroplasts and mitochondria. In addition, higher rates of organic acid synthesis because of NH4 nutrition may immobilize Ca and Mg within the roots. Ammonium also reduces the uptake of Ca and K by the roots, and is used only sparingly or not at all during the early growth of crops under poor light conditions [40].

**9**

*The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry*

The general conclusion is that proper N fertilizer application could be effective in improving fruit quality. Plants with low or moderate vegetative growth tend to have firmer fruits. Higher N doses decreased fruit size and increased pest and disease occurrence and fruit rot and malformation. Petiole sap nitrate testing is a standard method that determines the N requirement at different developmental stages of growth and would help to reduce uncertainty of time and amount of N

Imbalances in certain macronutrients can also have a pronounced effect on shape, and size [11]. Magnesium and phosphorous deficiency tend to decrease flower and fruit size and increase the incidence of albinism. Potassium-deficient plants may produce shriveled fruits with brown calyxes, fruits fail to develop full

Among microelements, boron (B) has a direct effect on fruit quality. For example, B deficiency causes distorted flowers and fruits, reduces fruit size and number, and increases malformation [11, 67]. The influence of B on phenol metabolism has also been well studied [39]. Fewer malformed fruit in plants receiving B can be correlated with a higher concentration of B both in leaves and fruit [66], which may be due to the significant role of B on pollen germination and pollen tube growth. Studies conducted by Sing [66] indicate that B application does not influence fruit quality in strawberry; however, B deficiency usually results in poor accumulation of TSS, and ascorbic acid. Other microelements also have roles in plant growth and development and are needed at lower concentrations compared to macronutrients. Iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and molybdenum (Mo) are needed at 40, 25, 20, 3, 0.4 ppm per dry matter of leaves, respectively [67]. No major effects of Fe, Cu, and Mn have been reported on fruit quality [67]. In general,

balanced fertilization has an important effect on both fruit yield and quality.

ized by an increase in reduced glutathione and better fruit taste [78].

Fruit quality has been observed to increase with saline solute concentration. A

ripening was accelerated in salt-stressed plants [75], and salinity had no effect on fruit number, but decreased fresh and dry weight [44]. In three different studies on the effect of salinity on two strawberry cultivars differing in their sensitivity to NaCl stress: cv. Elsanta (sensitive) and cv. Korona (less sensitive) [76–78], salinity decreased total soluble solids and sugar (especially sucrose) content. Fruit quality, characterized as taste, aroma, and texture by a panel decreased significantly in "Elsanta," but not in "Korona" [76, 78]. The more tolerant cv. Korona was character-

EC proved to be best in the winter in terms of fruit quality. Fruit

Salt stress increased the antioxidant capacity, antioxidants pools (ascorbic acid, anthocyanins, superoxide dismutase) and selected minerals such as Na+, Cl<sup>−</sup>, K+

N, P, and Zn2+, as well as lipid peroxidation in both cultivars [78], and also free and essential amino acid content, especially in cv. Elsanta. The ability of "Korona" to retain Cl<sup>−</sup> in the root system more effectively than "Elsanta" resulted in 41% less leaf Cl<sup>−</sup> at the highest salinity level and better growth under NaCl stress leading to

Strawberry plants need frequent irrigation due to a shallow root system, large leaf area, and fruits with high water content [79]. In a field study, it was found that irrigating at 200 hPa resulted in higher yield and better fruit quality when compared with irrigating at 300 hPa. Decreased fruit firmness and increased fruit size was also observed in irrigated plots [80, 81]. Particularly in light soils, irrigation significantly increases fruit yield and quality, and creates an opportunity for intensive

EC is preferred during the spring season whereas

,

*DOI: http://dx.doi.org/10.5772/intechopen.84619*

color, and have pulpy texture, and insipid taste [67].

solution strength of 1.3 mS cm<sup>−</sup><sup>1</sup>

relatively higher fruit yield and quality [76].

2.2 mS cm<sup>−</sup><sup>1</sup>

**5.4 Irrigation**

application [67].

#### *The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry DOI: http://dx.doi.org/10.5772/intechopen.84619*

The general conclusion is that proper N fertilizer application could be effective in improving fruit quality. Plants with low or moderate vegetative growth tend to have firmer fruits. Higher N doses decreased fruit size and increased pest and disease occurrence and fruit rot and malformation. Petiole sap nitrate testing is a standard method that determines the N requirement at different developmental stages of growth and would help to reduce uncertainty of time and amount of N application [67].

Imbalances in certain macronutrients can also have a pronounced effect on shape, and size [11]. Magnesium and phosphorous deficiency tend to decrease flower and fruit size and increase the incidence of albinism. Potassium-deficient plants may produce shriveled fruits with brown calyxes, fruits fail to develop full color, and have pulpy texture, and insipid taste [67].

Among microelements, boron (B) has a direct effect on fruit quality. For example, B deficiency causes distorted flowers and fruits, reduces fruit size and number, and increases malformation [11, 67]. The influence of B on phenol metabolism has also been well studied [39]. Fewer malformed fruit in plants receiving B can be correlated with a higher concentration of B both in leaves and fruit [66], which may be due to the significant role of B on pollen germination and pollen tube growth.

Studies conducted by Sing [66] indicate that B application does not influence fruit quality in strawberry; however, B deficiency usually results in poor accumulation of TSS, and ascorbic acid. Other microelements also have roles in plant growth and development and are needed at lower concentrations compared to macronutrients. Iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and molybdenum (Mo) are needed at 40, 25, 20, 3, 0.4 ppm per dry matter of leaves, respectively [67]. No major effects of Fe, Cu, and Mn have been reported on fruit quality [67]. In general, balanced fertilization has an important effect on both fruit yield and quality.

Fruit quality has been observed to increase with saline solute concentration. A solution strength of 1.3 mS cm<sup>−</sup><sup>1</sup> EC is preferred during the spring season whereas 2.2 mS cm<sup>−</sup><sup>1</sup> EC proved to be best in the winter in terms of fruit quality. Fruit ripening was accelerated in salt-stressed plants [75], and salinity had no effect on fruit number, but decreased fresh and dry weight [44]. In three different studies on the effect of salinity on two strawberry cultivars differing in their sensitivity to NaCl stress: cv. Elsanta (sensitive) and cv. Korona (less sensitive) [76–78], salinity decreased total soluble solids and sugar (especially sucrose) content. Fruit quality, characterized as taste, aroma, and texture by a panel decreased significantly in "Elsanta," but not in "Korona" [76, 78]. The more tolerant cv. Korona was characterized by an increase in reduced glutathione and better fruit taste [78].

Salt stress increased the antioxidant capacity, antioxidants pools (ascorbic acid, anthocyanins, superoxide dismutase) and selected minerals such as Na+, Cl<sup>−</sup>, K+ , N, P, and Zn2+, as well as lipid peroxidation in both cultivars [78], and also free and essential amino acid content, especially in cv. Elsanta. The ability of "Korona" to retain Cl<sup>−</sup> in the root system more effectively than "Elsanta" resulted in 41% less leaf Cl<sup>−</sup> at the highest salinity level and better growth under NaCl stress leading to relatively higher fruit yield and quality [76].

#### **5.4 Irrigation**

Strawberry plants need frequent irrigation due to a shallow root system, large leaf area, and fruits with high water content [79]. In a field study, it was found that irrigating at 200 hPa resulted in higher yield and better fruit quality when compared with irrigating at 300 hPa. Decreased fruit firmness and increased fruit size was also observed in irrigated plots [80, 81]. Particularly in light soils, irrigation significantly increases fruit yield and quality, and creates an opportunity for intensive

*Strawberry - Pre- and Post-Harvest Management Techniques for Higher Fruit Quality*

increased shelf life due to Ca application [66].

ances of other minerals in leaf tissue.

concentrations [74].

pronounced in the shaded conditions.

uptake of cations such as Ca<sup>+</sup>

which is toxic for the plant [40].

detoxification and low nitrate concentrations.

growth of crops under poor light conditions [40].

received Ca were firmer even after 5 days of storage [66].

of Ca did not affect fruit quality, regardless of cultivar, yet other studies have shown

Furthermore, Singh et al. [66] reported that preharvest Ca sprays greatly influenced fruit color during storage. In storage, fruit harvested from control plants turned darker whereas from the Ca spray treatment were comparatively brighter. Similarly, higher values of hue (a) and chroma (b) in such fruit indicate that fruit receiving Ca were redder and more vivid. Strawberries soften considerably during storage as a result of degradation of middle lamella, cell wall, and cortical parenchyma cells. By extension, cell wall strength, cell to cell contact and cellular turgor, which are greatly influenced by Ca may affect fruit firmness. Thus, fruits which

Calcium deficiency represents one of the most common issues for strawberry growers. Calcium plays a role in cell division and the maintenance of cell permeability and cell integrity, all of which directly influence factors such as firmness and shelf life [66]. Strawberry fruits from Ca-deficient plants are small, hard textured, acidic, seedy, or with patches covered densely with achenes, with increased deformity [17]. Calcium sprays increases fruit firmness, vitamin C and shelf life during storage [68]. However, there are reports that increasing Ca application did not affect sensory quality and decreased TA and TSS of strawberries. Calcium increased firmness and storage life up to 900 ppm. Higher concentration seems to create toxicity and imbal-

The form of Ca applied also changes the result. Application of gypsum at planting time did not influence fruit Ca content. Therefore, cultivar, form of Ca applied, and environmental factors must be considered during Ca fertilization of strawberries [68]. Nitrogen is another important nutrient for fruit quality with both positive and negative effects of N on yield and fruit quality reported. The effect of N on fruit chemical components is inconsistent and varies from year to year, depending on time and rate of application and other environmental factors [67]. Recommended optimum concentrations of leaf N for high-yielding strawberry fields in California, North Carolina, northeastern United States, and Ontario, Canada ranges from 2.0 to 4.0%, with samples collected mostly from the leaf blade [69–73]. Form of N also affects fruit quality. Ammonium up to a ratio of 1 to 6 nitrate increased fruit firmness, but reduced red color compared to nitrate alone. Fruit vitamin C, pH, and TSS decreased with addition of ammonium up to a ratio of 1:6 (ammonium: nitrate) and then returned to the original level at the ratio of 1.5:6. Ammonium reduced TA at all

Tabatabaei [40] demonstrated that both high concentrations of NO3 (100%) and NH4 (75%) has an inhibitory effect on growth of strawberry, and it becomes more

While low concentration of ammonium improved plant growth, higher concentrations, reduced growth due to the high demand for carbohydrates for ammonium

Another possible explanation is that a high concentration of NH4 reduces the

Higher concentration of NH4 significantly reduced postharvest life probably due to Ca deficiency in fruit. Calcium deficiency associated with NH4 nutrition can induce loss of membrane integrity which in turn may lower the concentration of potassium (K) and Mg and influence the function of chloroplasts and mitochondria. In addition, higher rates of organic acid synthesis because of NH4 nutrition may immobilize Ca and Mg within the roots. Ammonium also reduces the uptake of Ca and K by the roots, and is used only sparingly or not at all during the early

and increases the concentration of NH4

+ ,

and K+

**8**

strawberry production. Both sprinkler and drip irrigation systems produced the same result, but water use was considerably lower with drip irrigation [82].

When strawberries are exposed to long-term water stress, leaf, crown, and runner growth are decreased. Fruit number and weight (yield) also decreases even as fruit maturity is accelerated [83]. Therefore, strawberries are generally considered unfit for deficit irrigation. However, mild deficit irrigation has been tested as a method to limit water use, and depending on the cultivar, to increase the concentration of some taste- and health-related compounds. For example, [84] report that deficit irrigation reduced berry size but increased dry matter content, sugars and acids in cvs. Elsanta, Sonata, and Symphony but not in cvs. Florence and Christine.

#### **5.5 Cultural systems**

Strawberries are commonly grown on raised-beds using different polyethylene mulches. This system keeps the fruits clean, eases harvesting, saves water, and lowers herbicide use. Moreover, in Europe, strawberries grown on plastic mulches ripen a week earlier than those without mulch because of higher soil and canopy temperature, and reflection caused by the mulch may improve light conditions [39].

Significantly higher phenolic content has been reported in fruit from strawberry plants grown on plasticulture than in those grown in matted row culture. Additionally, higher anthocyanin content has been observed in strawberry fruits grown on plastic mulch compared to those grown on straw mulch. The elevated temperature inside the plastic may explain the higher phenolic content. White mulch increased the contents of the total phenolics and ellagic acid and the antioxidant activity in strawberry fruits more than brown mulch, whereas the total anthocyanin content was highest in fruits grown on brown mulch. Strawberries grown on red plastic mulch have been found to contain significantly higher amounts of aroma compounds than those grown on black mulch, which may be due to different light conditions caused by the mulch color [39].

Cultural systems affect plant metabolites such as total phenolic compounds, anthocyanin, and antioxidants. Hill plasticulture systems significantly increase total phenolic compounds, anthocyanin, antioxidants, and flavonoids compared to matted row systems. Cultural systems affect the quantity and quality of light reaching the plant and therefore, plant and soil temperatures, and soil moisture content. These conditions will affect plant growth and development and subsequently plant metabolites such as those mentioned previously [12, 51].

#### **5.6 Planting date**

Planting date in glasshouse production affected phenolic content, and a statistically significant interaction was found between planting date and fruit order [39]. The crop from the latest planting date seems to have the highest total phenolic content and antioxidant activity, whereas anthocyanin content was lowest. In a related study, it was found that harvest date affected the ellagic acid content, with prevailing temperature and rainfall during harvest assumed to cause the differences [39].

Fruit quality did not change with the cultural cycle (summer-spring versus fall-spring), but the berries harvested in the spring had higher vitamin C and sucrose content and lower nitrate content compared with berries harvested in the winter [79]. Several works have demonstrated flavor differences between crops grown during different seasons [19]. Planting date affects plant mineral content due to changes in nutrient solution strength and light intensity. At lower light intensity during winter, growers increase nutrient solution strength, which can lead to higher fruit nitrate content compared to the spring. This can be considered undesirable, since nitrates may pose a potential threat to human health [19].

**11**

*The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry*

Chemical composition in strawberry fruit varies by genotype and maturity. Following the pink stage, many phytonutrients are synthesized in parallel with the

Harvesting at optimal maturity is essential for ensuring good fruit quality since important changes in individual sugar and acid content occurs in the final stages of

Antioxidant capacity also varies considerably with maturity. Many phytonutrients are synthesized in parallel with the overall development and maturation and strawberry fruit harvested at ripe stage consistently yielded higher antioxidant values than those harvested at the pink stage [12, 16]. Strawberries have the highest oxygen radical absorbance capacity (ORAC) values during the green stages [15, 16], while fruit harvested at pink stage (50% maturity) had the lowest ORAC and

The concentration of total phenolic compounds is highest at the green stage and reduces during prolonged storage and processing. Ellagic acid concentration is highest in the early stages of fruit maturation (green strawberries) and gradually

Ascorbic acid content increased from green to the pink stage by about 95% and then did not change until berries were overripe, when it then decreased. Ascorbic

Overall quality and firmness of fruit harvested at the red ripe stage declined more rapidly than the white tip stage. Also, fruits were lighter and less red, reflecting less anthocyanin accumulation. Therefore, fruits harvested at three quarters red ripening stage can be stored for longer periods with better color and firmness than the fruit harvested when fully red. Strawberries harvested at early stages of color development (white stage) can become red during storage similar to commercially ripe fruit [15, 86]. This indicates that strawberries harvested at certain stages of maturity can synthesize pigment during storage under favorable conditions that are temperature dependent [45, 86] and can occur in darkness, but light can slightly

There are large variations in flavor quality between fruits per harvest and also from harvest to harvest. In strawberry, primary fruits are larger and ripen first and have less competition for resources. Therefore, there is a variation between primary, secondary, tertiary, and quaternary fruit in flavor and nutrient content. At each harvest, fruits from different stage of maturity and ripeness will increase the variability. Different harvests during the season may even have more variability than fruit ripening stage, because, environmental conditions such as light may alter flavor compounds as well. Previous data from tomatoes Anagnostou [36] suggested a strong correlation between juice sugar and solar radiation across one season. The results show the difficulty in interpreting data where there is a variable light

Soluble solids and sugars decreased as the harvest season progressed, while TA, ascorbic acid content and anthocyanins increased [36]. A steady decrease in SSC and sugars as the harvest season progressed was noticed, most probably because plants were exhausted. Low levels coincided with peak production, while the highest values were noticed during low and early production (January) periods characterized by very low light intensity and short days. Titratable acidity increased from January to June, in parallel with increases in day length and light intensity [36].

*DOI: http://dx.doi.org/10.5772/intechopen.84619*

overall development and maturation of the fruit.

2,2-diphenyl-1-picrylhydrazyl radical scavenging activity.

acid is lower in the inner than in the outer part of the fruit.

increase the rate of pigment formation [45].

**5.8 Harvest time and method**

integral as well as differences [36].

**5.7 Maturity**

ripening.

declines with ripening [85].

*The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry DOI: http://dx.doi.org/10.5772/intechopen.84619*

#### **5.7 Maturity**

*Strawberry - Pre- and Post-Harvest Management Techniques for Higher Fruit Quality*

**5.5 Cultural systems**

**5.6 Planting date**

strawberry production. Both sprinkler and drip irrigation systems produced the same result, but water use was considerably lower with drip irrigation [82].

When strawberries are exposed to long-term water stress, leaf, crown, and runner growth are decreased. Fruit number and weight (yield) also decreases even as fruit maturity is accelerated [83]. Therefore, strawberries are generally considered unfit for deficit irrigation. However, mild deficit irrigation has been tested as a method to limit water use, and depending on the cultivar, to increase the concentration of some taste- and health-related compounds. For example, [84] report that deficit irrigation reduced berry size but increased dry matter content, sugars and acids in cvs. Elsanta, Sonata, and Symphony but not in cvs. Florence and Christine.

Strawberries are commonly grown on raised-beds using different polyethylene mulches. This system keeps the fruits clean, eases harvesting, saves water, and lowers herbicide use. Moreover, in Europe, strawberries grown on plastic mulches ripen a week earlier than those without mulch because of higher soil and canopy temperature, and reflection caused by the mulch may improve light conditions [39]. Significantly higher phenolic content has been reported in fruit from strawberry plants grown on plasticulture than in those grown in matted row culture. Additionally, higher anthocyanin content has been observed in strawberry fruits grown on plastic mulch compared to those grown on straw mulch. The elevated temperature inside the plastic may explain the higher phenolic content. White mulch increased the contents of the total phenolics and ellagic acid and the antioxidant activity in strawberry fruits more than brown mulch, whereas the total anthocyanin content was highest in fruits grown on brown mulch. Strawberries grown on red plastic mulch have been found to contain significantly higher amounts of aroma compounds than those grown on black mulch, which may be due to different light conditions caused by the mulch color [39]. Cultural systems affect plant metabolites such as total phenolic compounds, anthocyanin, and antioxidants. Hill plasticulture systems significantly increase total phenolic compounds, anthocyanin, antioxidants, and flavonoids compared to matted row systems. Cultural systems affect the quantity and quality of light reaching the plant and therefore, plant and soil temperatures, and soil moisture content. These conditions will affect plant growth and development and subsequently plant

Planting date in glasshouse production affected phenolic content, and a statistically significant interaction was found between planting date and fruit order [39]. The crop from the latest planting date seems to have the highest total phenolic content and antioxidant activity, whereas anthocyanin content was lowest. In a related study, it was found that harvest date affected the ellagic acid content, with prevailing temperature and rainfall during harvest assumed to cause the differences [39]. Fruit quality did not change with the cultural cycle (summer-spring versus fall-spring), but the berries harvested in the spring had higher vitamin C and sucrose content and lower nitrate content compared with berries harvested in the winter [79]. Several works have demonstrated flavor differences between crops grown during different seasons [19]. Planting date affects plant mineral content due to changes in nutrient solution strength and light intensity. At lower light intensity during winter, growers increase nutrient solution strength, which can lead to higher fruit nitrate content compared to the spring. This can be considered undesirable,

metabolites such as those mentioned previously [12, 51].

since nitrates may pose a potential threat to human health [19].

**10**

Chemical composition in strawberry fruit varies by genotype and maturity. Following the pink stage, many phytonutrients are synthesized in parallel with the overall development and maturation of the fruit.

Harvesting at optimal maturity is essential for ensuring good fruit quality since important changes in individual sugar and acid content occurs in the final stages of ripening.

Antioxidant capacity also varies considerably with maturity. Many phytonutrients are synthesized in parallel with the overall development and maturation and strawberry fruit harvested at ripe stage consistently yielded higher antioxidant values than those harvested at the pink stage [12, 16]. Strawberries have the highest oxygen radical absorbance capacity (ORAC) values during the green stages [15, 16], while fruit harvested at pink stage (50% maturity) had the lowest ORAC and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity.

The concentration of total phenolic compounds is highest at the green stage and reduces during prolonged storage and processing. Ellagic acid concentration is highest in the early stages of fruit maturation (green strawberries) and gradually declines with ripening [85].

Ascorbic acid content increased from green to the pink stage by about 95% and then did not change until berries were overripe, when it then decreased. Ascorbic acid is lower in the inner than in the outer part of the fruit.

Overall quality and firmness of fruit harvested at the red ripe stage declined more rapidly than the white tip stage. Also, fruits were lighter and less red, reflecting less anthocyanin accumulation. Therefore, fruits harvested at three quarters red ripening stage can be stored for longer periods with better color and firmness than the fruit harvested when fully red. Strawberries harvested at early stages of color development (white stage) can become red during storage similar to commercially ripe fruit [15, 86]. This indicates that strawberries harvested at certain stages of maturity can synthesize pigment during storage under favorable conditions that are temperature dependent [45, 86] and can occur in darkness, but light can slightly increase the rate of pigment formation [45].

#### **5.8 Harvest time and method**

There are large variations in flavor quality between fruits per harvest and also from harvest to harvest. In strawberry, primary fruits are larger and ripen first and have less competition for resources. Therefore, there is a variation between primary, secondary, tertiary, and quaternary fruit in flavor and nutrient content. At each harvest, fruits from different stage of maturity and ripeness will increase the variability.

Different harvests during the season may even have more variability than fruit ripening stage, because, environmental conditions such as light may alter flavor compounds as well. Previous data from tomatoes Anagnostou [36] suggested a strong correlation between juice sugar and solar radiation across one season. The results show the difficulty in interpreting data where there is a variable light integral as well as differences [36].

Soluble solids and sugars decreased as the harvest season progressed, while TA, ascorbic acid content and anthocyanins increased [36]. A steady decrease in SSC and sugars as the harvest season progressed was noticed, most probably because plants were exhausted. Low levels coincided with peak production, while the highest values were noticed during low and early production (January) periods characterized by very low light intensity and short days. Titratable acidity increased from January to June, in parallel with increases in day length and light intensity [36].

Seasonal factor and environmental conditions affect fruit content and quality very strongly.

Organic acids that affect flavor (citrate and malate) and ascorbic acid were significantly higher in the spring than winter. This could be due to the higher carbohydrates as the precursors for ascorbic synthesis. Carotenoids are also available in strawberries, although less abundant than ascorbic acid. Unlike ascorbic acid, the amount of carotenoids is higher during winter than spring. This suggests that carotenoid synthesis is dependent on the interaction between temperature and light intensity [79].

The method of harvest and handling operations can determine the extent of physical injury and maturity variation, which both affect the nutritional quality of strawberries. Physical injury during harvest such as abrasions, cuts, and bruising can reduce the amount of ascorbic acid and increase fruit decay. Best harvest and handling practices should be implemented to reduce physical injury and maintain fruit quality [33].

#### **5.9 Pollination, fruit order, and crop load**

Inadequate pollination creates distorted strawberry fruit at maturity due to inadequate fertilized ovules, which secrete hormones necessary for fruit cell division and enlargement [11]. Insect pollination results in uniform strawberry fruit and bee (*Apis melilfera*) colonies are introduced into protected cultivations to pollinate flowers. Honey bees are not efficient in colder temperatures and other insects such as bumble bees are commonly used [87]. In Utah, field-grown strawberries pollinated by caged honey bees produced fewer malformed fruits than controls. Honey bees and large Diptera (*Eristalis* spp.) were the most common visitors to the strawberry flowers while sweet bees (*Halictus ligatus*) were the most efficient pollinators [88]. In Brazil, stingless bees (*Scaptotrigona* aff. *depilis* and *Nannotrigona testaceicornis*) work efficiently as strawberry pollinators in greenhouses [89].

Temperatures above 25°C can significantly affect pollen viability and germination and consequently yield and quality. However, certain strawberry cultivars produce heat-tolerant pollen, which in turn could result in higher fruit set [90, 91].

Fruit order significantly affected the phenolic content in fruits. In two separate experiments, the levels of the total phenolics, ellagic acid, and antioxidant activity were found to increase from primary to tertiary fruits. Fruit order caused at highest a 1.5–2.0-fold difference in phenolic acid content [39]. However, the highest anthocyanin content was found in secondary fruits.

Primary fruits are the largest and have more resources available for growth and protein synthesis and less available for the phenylalanine ammonium lyase enzyme to convert it to phenolic compounds. Another explanation is the dilution effect of larger cells with higher biomass in primary fruits [39].

In strawberry, the effect of crop load on fruit quality depends on the genotype. Low crop load is associated with higher total soluble solids in "Ventana" and "Candonga," but not in "Camarosa" [92]. Crop load also increases over time meaning that even at similar light levels, the amount of assimilates available to individual fruits will change throughout the harvest period. The greatest demand for assimilates will occur during the development of secondary and tertiary fruits [19]. Crop load also affects firmness, TSS, acidity, and anthocyanin [36].

#### **5.10 Chemical sprays and residues**

Evaporation of surface water from overhead irrigation or chemical, fertilizer, and pesticide sprays create an unpleasant strawberry fruit appearance [11].

**13**

*The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry*

However, strawberries cannot be exposed to free water after harvest meaning residual chemicals on fruit surfaces cannot be washed away. Furthermore, pest control products may indirectly change fruit flavor and composition. For example, mite control improved sweetness and flavor intensity of "Sweet Charlie" strawberries but had no effect on fruit color or firmness [93]. There are many commercial products that affect plant growth and development, which may or may not be plant growth regulators. These products seem to enhance fruit set and growth, resulting in bigger fruit size and higher yields, or protect the plants and fruits from biotic and

Plant growth stimulators (seaweed extract, mixture of an auxin plus gibberellic acid, and nitrophenolates) increased fruit yield, size, and total anthocyanin concentration of strawberry cv. Camarosa, but did not change other characteristics (i.e., fruit juice pH, TA and TSS concentration, organic acid and carbohydrate concentration and fruit color). In a taste panel, the mixture of auxin and gibberellic

In another experiment, strawberry plants were sprayed during fruit ripening

Chitosan increased firmness and reduced fruit decay, ripening rate, TA, and anthocyanin content during 4 weeks of storage. Formation of a chitosan film on fruit acts as a barrier for oxygen uptake thereby slowing the ripening process and modifying the atmosphere and ethylene levels without causing anaerobic respiration. In addition, chitosan coating can reduce desiccation by providing a moisture barrier as was reported earlier [95]. The reduced decay by chitosan is mostly related to delayed

Plants receiving salicylic acid (SA) during vegetative stage through their nutrient solution produced firmer fruits with less weight loss, decay, and better quality [96]. Weight loss is due to metabolic activity, respiration and transpiration, and it is possible that SA decreased respiration rate and fruit weight loss by closing stomata. Salicylic acid as an electron donor produces free radicals, which prevents normal respiration. Pre- and postharvest application of salicylic acid significantly increased strawberry ascorbic acid content, TSS, TA and total antioxidant potential, and prevented fungal growth [97]. Increased ascorbic acid is mostly due to the increased activity of ascorbate peroxidase, [12]. Also, increased antioxidant ability and antistress power of plants and fruits induced by SA prevents vitamin C destruction. Salicylic acid decreased fungal development, although not fungicidal. However, activity of defensive enzymes (peroxidase, chitinase, and phenylalanine ammonialyase) increased in pear after SA spray. Conversely, rapid decrease in endogenous SA of fruits during ripening is simultaneous with rapid softening of fruits. It has been shown that SA affects cell swelling, which leads to higher firmness of fruits

Recent studies show that silicon (Si) is a beneficial element for plant growth that plays an important role in plant resistance to biotic and abiotic stresses. Silicon improved strawberry plant fresh and dry weight, leaf area and relative water content, and yield under salinity stress. Both Si and salinity treatments increased acidity of fruit, but did not affect other fruit quality characteristics [98]. Silicon fertilization also reduced powdery mildew severity under high tunnel on all strawberry cultivars tested, and significantly increased yield of marketable fruits reaching as much as 300% with cv. Monterey [99]. A silicon-based wetter (Omex SW7) significantly increased the number and length of leaf hairs on both the upper

chitosan with no phytotoxic effect [95].

*DOI: http://dx.doi.org/10.5772/intechopen.84619*

abiotic stresses [94].

fruit senescence.

acid received the best score [94].

and after 10 days with 2, 4 and 6 g l<sup>−</sup><sup>1</sup>

and prevents fruit softening (Wang [12]).

**5.11 Silicon, and other natural compounds**

#### *The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry DOI: http://dx.doi.org/10.5772/intechopen.84619*

However, strawberries cannot be exposed to free water after harvest meaning residual chemicals on fruit surfaces cannot be washed away. Furthermore, pest control products may indirectly change fruit flavor and composition. For example, mite control improved sweetness and flavor intensity of "Sweet Charlie" strawberries but had no effect on fruit color or firmness [93]. There are many commercial products that affect plant growth and development, which may or may not be plant growth regulators. These products seem to enhance fruit set and growth, resulting in bigger fruit size and higher yields, or protect the plants and fruits from biotic and abiotic stresses [94].

Plant growth stimulators (seaweed extract, mixture of an auxin plus gibberellic acid, and nitrophenolates) increased fruit yield, size, and total anthocyanin concentration of strawberry cv. Camarosa, but did not change other characteristics (i.e., fruit juice pH, TA and TSS concentration, organic acid and carbohydrate concentration and fruit color). In a taste panel, the mixture of auxin and gibberellic acid received the best score [94].

In another experiment, strawberry plants were sprayed during fruit ripening and after 10 days with 2, 4 and 6 g l<sup>−</sup><sup>1</sup> chitosan with no phytotoxic effect [95]. Chitosan increased firmness and reduced fruit decay, ripening rate, TA, and anthocyanin content during 4 weeks of storage. Formation of a chitosan film on fruit acts as a barrier for oxygen uptake thereby slowing the ripening process and modifying the atmosphere and ethylene levels without causing anaerobic respiration. In addition, chitosan coating can reduce desiccation by providing a moisture barrier as was reported earlier [95]. The reduced decay by chitosan is mostly related to delayed fruit senescence.

Plants receiving salicylic acid (SA) during vegetative stage through their nutrient solution produced firmer fruits with less weight loss, decay, and better quality [96]. Weight loss is due to metabolic activity, respiration and transpiration, and it is possible that SA decreased respiration rate and fruit weight loss by closing stomata. Salicylic acid as an electron donor produces free radicals, which prevents normal respiration. Pre- and postharvest application of salicylic acid significantly increased strawberry ascorbic acid content, TSS, TA and total antioxidant potential, and prevented fungal growth [97]. Increased ascorbic acid is mostly due to the increased activity of ascorbate peroxidase, [12]. Also, increased antioxidant ability and antistress power of plants and fruits induced by SA prevents vitamin C destruction. Salicylic acid decreased fungal development, although not fungicidal. However, activity of defensive enzymes (peroxidase, chitinase, and phenylalanine ammonialyase) increased in pear after SA spray. Conversely, rapid decrease in endogenous SA of fruits during ripening is simultaneous with rapid softening of fruits. It has been shown that SA affects cell swelling, which leads to higher firmness of fruits and prevents fruit softening (Wang [12]).

#### **5.11 Silicon, and other natural compounds**

Recent studies show that silicon (Si) is a beneficial element for plant growth that plays an important role in plant resistance to biotic and abiotic stresses. Silicon improved strawberry plant fresh and dry weight, leaf area and relative water content, and yield under salinity stress. Both Si and salinity treatments increased acidity of fruit, but did not affect other fruit quality characteristics [98]. Silicon fertilization also reduced powdery mildew severity under high tunnel on all strawberry cultivars tested, and significantly increased yield of marketable fruits reaching as much as 300% with cv. Monterey [99]. A silicon-based wetter (Omex SW7) significantly increased the number and length of leaf hairs on both the upper

*Strawberry - Pre- and Post-Harvest Management Techniques for Higher Fruit Quality*

very strongly.

light intensity [79].

**5.9 Pollination, fruit order, and crop load**

work efficiently as strawberry pollinators in greenhouses [89].

anthocyanin content was found in secondary fruits.

larger cells with higher biomass in primary fruits [39].

load also affects firmness, TSS, acidity, and anthocyanin [36].

**5.10 Chemical sprays and residues**

Seasonal factor and environmental conditions affect fruit content and quality

Organic acids that affect flavor (citrate and malate) and ascorbic acid were significantly higher in the spring than winter. This could be due to the higher carbohydrates as the precursors for ascorbic synthesis. Carotenoids are also available in strawberries, although less abundant than ascorbic acid. Unlike ascorbic acid, the amount of carotenoids is higher during winter than spring. This suggests that carotenoid synthesis is dependent on the interaction between temperature and

The method of harvest and handling operations can determine the extent of physical injury and maturity variation, which both affect the nutritional quality of strawberries. Physical injury during harvest such as abrasions, cuts, and bruising can reduce the amount of ascorbic acid and increase fruit decay. Best harvest and handling practices should be implemented to reduce physical injury and maintain fruit quality [33].

Inadequate pollination creates distorted strawberry fruit at maturity due to inadequate fertilized ovules, which secrete hormones necessary for fruit cell division and enlargement [11]. Insect pollination results in uniform strawberry fruit and bee (*Apis melilfera*) colonies are introduced into protected cultivations to pollinate flowers. Honey bees are not efficient in colder temperatures and other insects such as bumble bees are commonly used [87]. In Utah, field-grown strawberries pollinated by caged honey bees produced fewer malformed fruits than controls. Honey bees and large Diptera (*Eristalis* spp.) were the most common visitors to the strawberry flowers while sweet bees (*Halictus ligatus*) were the most efficient pollinators [88]. In Brazil, stingless bees (*Scaptotrigona* aff. *depilis* and *Nannotrigona testaceicornis*)

Temperatures above 25°C can significantly affect pollen viability and germination and consequently yield and quality. However, certain strawberry cultivars produce heat-tolerant pollen, which in turn could result in higher fruit set [90, 91]. Fruit order significantly affected the phenolic content in fruits. In two separate experiments, the levels of the total phenolics, ellagic acid, and antioxidant activity were found to increase from primary to tertiary fruits. Fruit order caused at highest a 1.5–2.0-fold difference in phenolic acid content [39]. However, the highest

Primary fruits are the largest and have more resources available for growth and protein synthesis and less available for the phenylalanine ammonium lyase enzyme to convert it to phenolic compounds. Another explanation is the dilution effect of

In strawberry, the effect of crop load on fruit quality depends on the genotype.

Low crop load is associated with higher total soluble solids in "Ventana" and "Candonga," but not in "Camarosa" [92]. Crop load also increases over time meaning that even at similar light levels, the amount of assimilates available to individual fruits will change throughout the harvest period. The greatest demand for assimilates will occur during the development of secondary and tertiary fruits [19]. Crop

Evaporation of surface water from overhead irrigation or chemical, fertilizer, and pesticide sprays create an unpleasant strawberry fruit appearance [11].

**12**

and lower surfaces of strawberry leaves and reduced the number of germinating powdery mildew (*Podosphaera aphanis*) ascospores and colonies. Moreover, potassium carbonate alone or mixed with Omex SW7 significantly reduced the number of germinating ascospores and colonies [100].

## **6. Conclusion**

Several reports confirm significant (35–50%) loss of horticultural produce after harvest. In strawberry, preharvest management is a prerequisite for producing good quality fruit. Fruit quality and nutrient content of strawberries varies widely depending on the variety and environmental factors. Berry fruits are extremely perishable and have a short market life. Because strawberry quality cannot be improved after harvest, the role of preharvest factors must be understood in order to improve the shelf life.

Results indicate that the effect of genotype on strawberry fruit and nutritional quality is stronger than that of growing conditions and cultivars could be selected for maximum adaptability to the environmental conditions and market demand.

Environmental conditions seem to have a major influence on nutritional and flavor compounds in strawberries. Preharvest conditions such as light intensity can affect strawberry fruit quality and phytonutrient content. The color of plastic mulches frequently used on raised beds also affects fruit quality. Plant growth and development is largely affected by temperature, which affects cellular compounds and their structure and fruit firmness. Changes in the composition of atmospheric CO2 and ozone constituents due to climate change may also affect fruit quality. Soil types, fertilization, composts, and mulching influence the water and nutrient supply to the plant and can affect the nutritional composition, ascorbic acid content, and antioxidant activity of harvested fruit. The use of alternative substrates (soilless culture) is a common cultural method in strawberries, especially in protected environments that has been shown to improve fruit yield and quality. Nitrogen and Ca are among the most critical elements for improving strawberry yield and quality. Strawberry plants need frequent irrigation due to a shallow root system, large leaf area, and fruits with high water content.

Cultural practices affect strawberry metabolites significantly. Higher phenolic content has been reported in fruit from strawberry plants grown on plasticulture than in those grown in matted row culture. Also, there is a large variation in flavor quality between fruits per harvest and from harvest to harvest.

Some of these environmental factors can be optimized in open fields according to the light and temperature conditions, such as planting date, mulch color and fertilization, although, their interactions may be hard to control. Other environmental factors can only be manipulated under protected cultivation. In general, to obtain reliable data on fruit and nutritional quality, when there is such a larger variation in growing conditions, other factors should be closely monitored.

**15**

**Author details**

provided the original work is properly cited.

Toktam Taghavi\*, Rafat Siddiqui and Laban K. Rutto

\*Address all correspondence to: ttaghavi@vsu.edu

College of Agriculture, Virginia State University, Petersburg, VA, USA

© 2019 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,

*The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry*

*DOI: http://dx.doi.org/10.5772/intechopen.84619*

*The Effect of Preharvest Factors on Fruit and Nutritional Quality in Strawberry DOI: http://dx.doi.org/10.5772/intechopen.84619*
