Studies of chlorophyll fluorescence intensity in apricot leaves during wilting processes

This work characterises the chlorophyll fluorescence intensity of apricot leaves in the process of dehydration and identification of cultivars and forms with high potential drought resistance. The experiment was performed using selected leaves of two cultivars of apricot breeding (‘Kryumskij Amur’ - control), the introduction ‘Bukuriya’, Nikita Botanical Gardens, and promising hybrid ‘84-929’. We found that leaves of studied genotypes in 24 h of wilting lose 42.7 (‘84-929’) to 48.4% (‘Bukuriya’) of water. Recovery of leaves’ turgor was also significantly varied. In ‘Kryumskij Amur’ full water content in leaves led to decrease of the photosynthetic apparatus efficiency During this period of wilting efficiency of primary photosynthesis reactions (F_v/F_o) decreased in 15% and the rate of photosynthesis systems photosynthetic ((F_m- F_st)/F_m) and photochemical (F_m/F_st) activity was 1.3-1.5-fold inhibited. The hybrid form ‘84-929’ noted the most stable rate of photosynthetic processes during the long period of wilting (up to 12 h). The lowest curve points were recorded in ‘Bukuriya’, indicating a weak drought resistance of this cultivar. Higher drought tolerance is a characteristic of ‘Kryumskij Amur’ due to its water-holding capacity of leaves.