The effect of dehydration on the functional state of the leaf apparatus in some apricot (Prunus armeniaca L.) cultivars

The article presents the results of evaluating the activity of the photosynthetic apparatus in the leaf blades of some apricot (Prunus armeniaca L.) cultivars by the method of chlorophyll a fluorescence induction kinetics changes. Two cultivars of Russian breeding (‘Yaltinets’ and ‘Naslazhdenie’) and one interspecific hybrid of apricot and cherry plum – ‘Briol 38’ were compared. A cultivar of foreign breeding – ‘Vardaguin Vagdaas’ was used as a control cultivar. The photosynthetic activity of the leaves was studied under native conditions, as well as after artificial dehydration. The studies of chlorophyll fluorescence were carried out on a MINI-PAM II portable pulsed fluorimeter (Heinz Walz, Germany, 2017). The parameters of photosynthetic activity in the leaves were measured at time intervals of 4, 8, 12, and 24 h. Water content, water holding capacity, water deficiency of leaves and turgor recovery rate were also considered. The loss of water in leaves per day was 22.2% for ‘Yaltinets’, 23.9% for ‘Vardaguin Vagdaas’, 29.4% for ‘Naslazhdenie’ and 34.3% for the hybrid ‘Briol 38’. ‘Yaltinets’ is superior to all studied cultivars in the ability of the photosynthetic apparatus to withstand dehydration and maintain high photosynthesis productivity. After 24 h of leaves dehydration in ‘Yaltinets’, the index (F_m-F_t)/F_m decreased by 8.3%, Rfd by 31.2%, F_v and F_v/F_m remained unchanged, and Y(II) increased by 6.3%. ‘Vardaguin Vagdaas’ also demonstrated high resistance of PS II to arid conditions. An interspecific hybrid of apricot and cherry plum Briol 38 is tolerant to short-term dehydration of leaf tissues, but longer dehydration leads to significant malfunctions and damages in PS II.