Physiological features of red currant varieties and selected seedling adaptation to drought and high temperature

Adaptation to weather conditions is an important feature of cultivars. To assess plant adaptability, we applied a physiological test of Ribesia (Berl.) Jancz. leaf resistance to abiotic factors during vegetation. The effect of high temperatures and drought on red currant plant photosynthetic apparatus and water regime was studied in 2011-2013 in the Central-Chernozem region (Orel region). Five varieties and three selected seedling genotypes of different eco-geographic and genetic origin were used including the derivatives of Ribes petraeum Wulf., R. vulgare Lam. and R. multiflorum Kit. (of these, six genotypes were originated in VNIISPK). Leaves of red currant plants are known to have a mesomorphic structure characteristic of Ribesia (Berl.) Jancz. subgenus. In this paper, it was shown that the morphological characteristics of leaves (i.e., shape, venation) are determined by the biological features of varieties while growing conditions alter the anatomical structure. We found a positive correlation between the leaf area and hydrothermal coefficient ( r = +0.99) and negative correlation between the leaf area and environment temperature ( r = -0.97). An increase in leaf thickness, the expansion of spongy parenchyma cells, a decrease in chlorophylls (both Chla and Chla + Chlb), as well as elevated carotenoid level are the response to stress factors during vegetation. The ratio coefficient of chlorophyll sum to carotenoids is considered as one of the adaptation indices. High coefficients were revealed in Hollandische Rote variety (5.14) and 1426-21-80 (5.51). Correlations between the chlorophyll sum and water loss ( r = -1.00) as well as chlorophyll sum and fraction of available water ( r = +0.98) were ascertained. The pigment content, fractional composition of water and water holding capacity of leaves are interconnected with the water shortage. The positive correlation of air temperature and water deficit ( r = +0.84) has been noted. The total water content in red currant leaves depends on the shoot growth, leaf age, variety, meteorological conditions and is not the main indicator of resistance to high temperatures and drought. Ratios of bound and free water and water holding capacity of leaves vary depending on meteorological conditions and water availability. In 2012 the weather conditions were unfavorable, and in all red currant genotypes the increase of the coefficient of bound water to available water as well as drop in water loss were observed. According to the parameters of water regime, Hollandische Rote variety and 1426-21-80 displayed high adaptability. The laboratory diagnostic methods were confirmed by the field data of genotype resistance under high temperature and moisture deficiency. Thus, the physiological express tests are suitable for estimation of red currant plant adaptability to environmental factors in the course of breeding. A comprehensive assessment showed diverse ecological plasticity in the plants with different Ribesia (Berl.) Jancz. subgenus species in the pedigree. The derivatives of Ribes petraeum Wulf. (Hollandische Rote) and R. multiflorum Kit. (1426-21-80) showed the highest tolerance to drought conditions during the vegetation season in the Central Chernozem region. The varieties and seedlings derived from R. vulgare Lam. had low drought resistance.