**3. Features of water regime in red currants (drought resistance, heat hardiness)**

Changes in the hydration of tissues and their water balance under the influence of adverse environmental conditions are reflected in the level, direction, and relationship of physiological processes that determine the formation of the crop and its quality. The ability to retain and economically consume water in arid conditions is a protective and adaptive reaction of resistant plants, which is due to a number of internal factors [33, 43].

It is established that the increase of water-holding capacity of leaves in extreme conditions of water supply allows stable red currant plants to regulate water metabolism [33, 41]. High water-holding capacity against the background of low water potential (61–67%) was observed in the varieties "Jonkheer Van Tets," "Hollandische Weisse," and "Englische Grosse Weisse." It is noted that the water potential of red currant leaves is not the main indicator of plant resistance to drought, because it depends on a number of factors (weather and climatic conditions, genotype, leaf age, shoot growth, and berry formation). The maximum reduction of water potential of leaf tissues in representatives of the subgenus *Ribesia* (Berl.) Jancz. occurs during the formation of berries, as most of the water is used to form the ovary [10, 42].

The resistance of red currants to hyperthermia is determined by the high content of bound water and water-holding capacity of leaves, low water deficit, and intensity of transpiration [43–45]. High values of the coefficient of bound water to free water and minimal water losses were observed in the variety "Hollandische Rote" and selected form 1426-21-80. The genotypes of these samples of *R. petraeum* Wulf. and *R. multiflorum* Kit. species exhibit higher adaptability to high temperatures against the background of soil moisture deficit (**Table 2**) [10]. In terms of transpiration intensity, red currant samples exhibit different mechanisms of adaptation to drought: either reduce the level of transpiration intensity (plants save water) or the level of transpiration intensity remains high (drought level for these genotypes is not critical) [43].

The relationship between physiological characteristics was revealed in representatives of different red currant species, which was confirmed by the coefficient of pair correlation between the amount of chlorophylls and water loss (r = −1.00), the amount of chlorophylls, and the amount of free water (p = +0.98). The content of pigments, fractional composition of water, and water-holding capacity of the leaf were associated with the development of water deficit, which depended on the air temperature (r = +0.84). The relationship between water regime indicators and meteorological features of the growing season was described using multiple regression coefficients (**Table 3**) [10].

In the study of plant resistance to abiotic environmental factors, their ability to withstand high air temperatures is important. Abnormally high temperatures, regardless of the dehydrating effect of dried soil and air, lead to disruption of water metabolism in plants and damage to membranes and proteins of the cell [46–50]. In this regard, an important feature of the variety is heat resistance [51]. Heat resistance largely depends on the duration of high temperatures and their absolute value. Temperature limits are specific to an individual genotype. In most cases, fruit plants begin to suffer when the temperature rises to 35–40°C. At these and higher temperatures, normal physiological functions are inhibited, and at temperatures around 50°C protoplasm, coagulation and cell death may occur. The exceeding the optimum temperature level leads to partial or global denaturation of proteins. In heat-resistant genotypes in the lipid complex, the saturated fatty acids predominate, and their appearance is a consequence of adaptation to this damaging factor. The mechanism of increasing the heat resistance is interconnected with the genetic apparatus of the cell and is aimed at stabilizing the membrane lipids in the direction of reducing their poly saturation. Under the action of elevated temperatures in the cells, the synthesis of stress proteins is induced [52]. Heat resistance is also associated with a certain

**201**

assessment [34, 53–64].

**Table 2.**

**Table 3.**

Rote" (*R. petraeum* Wulf.) [66].

*Physiological Features of Red Currant Adaptation to Drought and High Air Temperatures*

"Hollandische Rote" 1.33 35.82 2.09 20.36 2.03 21.11 1.82 25.76 1426-21-80 1.31 36.16 2.41 20.62 2.09 19.37 1.94 25.38 1432-29-98 1.12 30.17 1.42 25.01 1.20 26.98 1.25 27.39 "Jonkheer Van Tets" 1.01 38.10 1.31 21.85 1.04 27.40 1.12 29.12 1518-37-14 0.96 40.91 1.06 27.62 1.08 26.66 1.03 31.73 "Niva" 0.82 42.56 1.71 24.84 1.50 25.58 1.34 30.99 "Dana" 0.70 40.97 1.76 25.51 1.66 25.44 1.37 30.64 "Rosa" 0.63 39.75 0.98 26.82 0.87 27.85 0.83 31.47

*Notes: BW/FW—ratio of bound and free water; WL—water loss in 24 hours; % of water content, LSD05 for BW/*

*The main indicators of the water regime in red currant varieties from the Russian Research Institute of Fruit Crop* 

2011 2012 2013 Average **BW/FW WL, % BW/FW WL, % BW/FW WL, % BW/FW WL, %**

stage of plant development: young actively growing tissues are less stable than old ones. For berry plants, high temperatures are especially dangerous during flowering, because they cause sterility of flowers and the fall of ovaries. Plant organs differ in their heat resistance: shoots and buds are most stable, and the root system is less

*Correlation between physiological indicators and meteorological conditions in studied red currant varieties from* 

Russian and foreign researchers have achieved certain results in the study of water metabolism and physiological and biochemical parameters of resistance of fruit plants and developed methods for determining heat resistance. Water loss and the degree of water content recovery are informative indicators of heat resistance

The effect of temperature "shock" +50°C on the red currant genotypes showed that this culture does not have high heat resistance. Leaves at a young age (less heat-resistant) are most severely damaged by high temperatures; the older the leaf, the higher its heat resistance [65]. The degree of water recovery in red currant leaves increases by the time of berry ripening. The leaves of red currant genotypes recover water better during berry ripening and are less susceptible to damage by temperature +50°C; they are more heat-resistant than the leaves during the active growth of shoots. One hundred percent recovery of water loss does not occur after exposure to temperature stress (+50°C) on the leaf. The most heat-resistant varieties are considered "Niva" (*R. vulgare* Lam.) and "Hollandische

stable. The cambial tissue is most stable among tissues.

*the Russian Research Institute of Fruit Crop Breeding, Orel [10].*

*DOI: http://dx.doi.org/10.5772/intechopen.85033*

*Breeding, Orel, in 2011–2013 vegetation period [10].*

**Variety name/code (В) Year (А)**

LSD05 0.08 2.06 0.11 3.03 0.14 1.86

*FW^—A, 2.18; B, 4.59; and AB, 7.95; and LSD05 for WL—A, 0.13; B, 0.21; and AB, 0.37.*

**Indicator Regression ratio** Hydration 0.90×F; r = 0.22 Free water fraction 0.84×F; r = 0.33 Water loss −0.88×F; r = 0.30 *Notes: F—the values of hydrothermal coefficient; and r—the standard error of the experiment.* *Physiological Features of Red Currant Adaptation to Drought and High Air Temperatures DOI: http://dx.doi.org/10.5772/intechopen.85033*


*Notes: BW/FW—ratio of bound and free water; WL—water loss in 24 hours; % of water content, LSD05 for BW/ FW^—A, 2.18; B, 4.59; and AB, 7.95; and LSD05 for WL—A, 0.13; B, 0.21; and AB, 0.37.*

#### **Table 2.**

*Drought - Detection and Solutions*

**hardiness)**

**3. Features of water regime in red currants (drought resistance, heat** 

formation of berries, as most of the water is used to form the ovary [10, 42].

season was described using multiple regression coefficients (**Table 3**) [10].

In the study of plant resistance to abiotic environmental factors, their ability to withstand high air temperatures is important. Abnormally high temperatures, regardless of the dehydrating effect of dried soil and air, lead to disruption of water metabolism in plants and damage to membranes and proteins of the cell [46–50]. In this regard, an important feature of the variety is heat resistance [51]. Heat resistance largely depends on the duration of high temperatures and their absolute value. Temperature limits are specific to an individual genotype. In most cases, fruit plants begin to suffer when the temperature rises to 35–40°C. At these and higher temperatures, normal physiological functions are inhibited, and at temperatures around 50°C protoplasm, coagulation and cell death may occur. The exceeding the optimum temperature level leads to partial or global denaturation of proteins. In heat-resistant genotypes in the lipid complex, the saturated fatty acids predominate, and their appearance is a consequence of adaptation to this damaging factor. The mechanism of increasing the heat resistance is interconnected with the genetic apparatus of the cell and is aimed at stabilizing the membrane lipids in the direction of reducing their poly saturation. Under the action of elevated temperatures in the cells, the synthesis of stress proteins is induced [52]. Heat resistance is also associated with a certain

The resistance of red currants to hyperthermia is determined by the high content of bound water and water-holding capacity of leaves, low water deficit, and intensity of transpiration [43–45]. High values of the coefficient of bound water to free water and minimal water losses were observed in the variety "Hollandische Rote" and selected form 1426-21-80. The genotypes of these samples of *R. petraeum* Wulf. and *R. multiflorum* Kit. species exhibit higher adaptability to high temperatures against the background of soil moisture deficit (**Table 2**) [10]. In terms of transpiration intensity, red currant samples exhibit different mechanisms of adaptation to drought: either reduce the level of transpiration intensity (plants save water) or the level of transpiration intensity remains high (drought level for these genotypes is not critical) [43].

The relationship between physiological characteristics was revealed in representatives of different red currant species, which was confirmed by the coefficient of pair correlation between the amount of chlorophylls and water loss (r = −1.00), the amount of chlorophylls, and the amount of free water (p = +0.98). The content of pigments, fractional composition of water, and water-holding capacity of the leaf were associated with the development of water deficit, which depended on the air temperature (r = +0.84). The relationship between water regime indicators and meteorological features of the growing

Changes in the hydration of tissues and their water balance under the influence of adverse environmental conditions are reflected in the level, direction, and relationship of physiological processes that determine the formation of the crop and its quality. The ability to retain and economically consume water in arid conditions is a protective and adaptive reaction of resistant plants, which is due to a number of internal factors [33, 43]. It is established that the increase of water-holding capacity of leaves in extreme conditions of water supply allows stable red currant plants to regulate water metabolism [33, 41]. High water-holding capacity against the background of low water potential (61–67%) was observed in the varieties "Jonkheer Van Tets," "Hollandische Weisse," and "Englische Grosse Weisse." It is noted that the water potential of red currant leaves is not the main indicator of plant resistance to drought, because it depends on a number of factors (weather and climatic conditions, genotype, leaf age, shoot growth, and berry formation). The maximum reduction of water potential of leaf tissues in representatives of the subgenus *Ribesia* (Berl.) Jancz. occurs during the

**200**

*The main indicators of the water regime in red currant varieties from the Russian Research Institute of Fruit Crop Breeding, Orel, in 2011–2013 vegetation period [10].*


*Notes: F—the values of hydrothermal coefficient; and r—the standard error of the experiment.*

#### **Table 3.**

*Correlation between physiological indicators and meteorological conditions in studied red currant varieties from the Russian Research Institute of Fruit Crop Breeding, Orel [10].*

stage of plant development: young actively growing tissues are less stable than old ones. For berry plants, high temperatures are especially dangerous during flowering, because they cause sterility of flowers and the fall of ovaries. Plant organs differ in their heat resistance: shoots and buds are most stable, and the root system is less stable. The cambial tissue is most stable among tissues.

Russian and foreign researchers have achieved certain results in the study of water metabolism and physiological and biochemical parameters of resistance of fruit plants and developed methods for determining heat resistance. Water loss and the degree of water content recovery are informative indicators of heat resistance assessment [34, 53–64].

The effect of temperature "shock" +50°C on the red currant genotypes showed that this culture does not have high heat resistance. Leaves at a young age (less heat-resistant) are most severely damaged by high temperatures; the older the leaf, the higher its heat resistance [65]. The degree of water recovery in red currant leaves increases by the time of berry ripening. The leaves of red currant genotypes recover water better during berry ripening and are less susceptible to damage by temperature +50°C; they are more heat-resistant than the leaves during the active growth of shoots. One hundred percent recovery of water loss does not occur after exposure to temperature stress (+50°C) on the leaf. The most heat-resistant varieties are considered "Niva" (*R. vulgare* Lam.) and "Hollandische Rote" (*R. petraeum* Wulf.) [66].

Field assessment of red currant plants was carried out in Adygea after a long and gradually increasing heat in 1998. "Jonkheer Van Tets," "Natali," "Nenagliadnaya," "Boulogne Blanche," and *Ribes biebersteinii* Berl. showed resistance to heat (damage up to 2.5 points). The red currant samples of "Englische Grosse Weisse," "Hollandische Weisse," "Boulogne Rouge," "Versailles Rouge," "White Viksne," "Hollandische Weisse," and "London Market" dropped all the leaves, but the kidneys were still alive. Necrotic spots of different degrees appeared on the leaves of "Jonkheer Van Tets," "Nenagliadnaya," and "Boulogne Blanche" [33].
