Evaluation of raspberry drought tolerance

Abstract

Physiological parameters of drought tolerance of fi ve raspberry varieties (‘Meteor’, ‘Gusar’, ‘Lavina’, ‘Patricija’, and ‘Ulyabka’) and seven selected raspberry forms (4-122-2, 6-125-3, 1-76-1, 6-125-4, 2-83-21, 1-76-25, 2-90-3) were investigated. Experiments were conducted in 2022–2023 at the Kokinsky experimental station of the Federal Horticultural Center for Breeding, Agrotechnology and Nursery (Bryansk Oblast) and at the Center for Collective Use of Bryansk State Agrarian University. Drought tolerance was assessed based on the indices of total leaf water content, water defi cit, and water-retaining capacity in the phenophases of budding (May) and fruiting (July). The analysis showed that within one vegetation period, the total leaf water content and water-retaining capacity decreased from the phase of budding to that of fruiting, compared to water defi cit, which showed an inverse trend. The water-retaining capacity of the studied varieties was found to be higher in a drier season than in a moderatelyhumid year. A signifi cant variability among genotypes was observed in terms of water regime. During the fruiting phase, the total leaf water content decreased to an average level in all the studied genotypes (less than 70.0 %), except for the ‘Gusar’ and ‘Lavina’ varieties which demonstrated lower levels (less than 60.0 %). Forms outperforming in a number of leaf water regime parameters were identifi ed. Thus, the ‘Meteor’ variety, although showing high values of water content in the budding phenophase, was characterized by low water losses after 6-hour wilting (less than 30.0 %) and a leaf water defi cit (less than 10.0 %). Water defi cit in the ‘Ulyabka’ variety, as well as 6-125-4 and 2-90-3 selected forms, exceeded 10.0 % in the fruiting phenophase, corresponding to the average level of drought tolerance. The 2-83-21 form showed a reduced water-retaining capacity in the fruiting phenophase (water losses exceeded 30.0 %).