Physiological aspects of drought resistance of cherry varieties

Abstract

There is an abnormal increase in average summer temperature in the southern region (Krasnodar Territory). This, more than ever, actualizes the problem of identifying drought-resistant varieties of fruit crops, including cherry. The purpose of this research was to study the physiological indicators of water regime: loss of water, water-holding capacity, leaf water content, abscisic acid content in leaves of different varieties of Cerasus vulgaris Mill., which determine resistance to temperature stress, as well as to identify the most drought-tolerant varieties to optimize the range of varieties for the south of our country. The studies were carried out in 2018–2019 in the Prikuban fruit-growing zone of the Krasnodar Territory. Sixteen varieties of Cerasus vulgaris Mill. were the objects of the research. Varieties ʻKrasnodarskaya sladkayaʼ and ʻKazachkaʼ served as a control. Planting schemes – 6 × 4 m and 5 × 3 m. Soil – chernozems leached. pHwater – 6.8–7.22. Humus content – 3.47 %. In summer, meteorological conditions were characterized by an abnormal temperature rise (up to 39.3 ℃) and extended periods of drought. Studying of water regime was carried out according to the modified methodology of M. D. Kushnerenko using the gravimetric method. In laboratory experiments, we used the capillary electrophoresis “Kapel 104 P” (power supply with a positive polarity; equipped with a photometric detector; set wavelength – 254 nm). In the course of the research, we revealed that the water content in cherry leaves during the period of the adverse draught (in July) was 57.9 %; in the context of studied cherry varieties, it varied insignificantly (Cv = 4.4 %). For two hours, the loss of water by the leaf apparatus was not high – from 6.5 % to 11.9 % with a low coefficient of variation by varieties (Cv = 1.9 %). The water-holding capacity of leaf tissues was 19.6 %, the range of variability of which was insignificant by varieties (Cv = 18.0–24.2 %). The average content of abscisic acid in cherry leaves was 4.3 mg/kg and varied depending on the studied cherry varieties within the range of 1.5–14.2 mg/kg. According to the complex of physiological indicators of the water regime (low water loss (6.5–7.9 %), high water-holding capacity (19.4–24.2 %) and leaf water content (58.1–61.9 %), as well as increased abscisic acids content (11.0–14.2 mg/kg)), such cherry varieties/cultivars as ʻDuke Ivanovnaʼ, ʻDuke Khodosaʼ, ʻFeyaʼ, ʻMolodezhnayaʼ and ʻErdi Botermoʼ were classified as highly drought-resistant. They are recommended for expanding the range of adaptive cherry varieties/cultivars in the southern part of Russia.