Approach to assessing the drought resistance of grapes on model intact leaves

Abstract

On the one hand, water scarcity poses challenges to the growth, development, longevity and resistance of grapes to diseases and low temperatures, on the other hand, however, it is necessary to obtain a high-quality harvest. Under the conditions of increasing continentality of the climate, it is of great importance to breed the cultivars characterised by effective fruiting without damaging the grape plant under drought conditions. Identifying characteristics of drought resistance in grapes is a challenging task, given the size of the plants, the extended development period, the absence of a specific criterion for drought resistance and the labour-intensive and time-consuming nature of the exploratory analysis. This study proposes the use of intact leaves from a specific grape variety placed in controlled environmental conditions as a model system. The paper assesses the applicability of intact grape leaves as a reliable model for evaluating drought resistance in the cultivar. It compares variations in physiological parameters—electrolyte leakage, chlorophyll stability index, and malonyldialdehyde content—observed in intact leaves under the influence of sorbitol and in leaf discs under the influence of polyethylene glycol with different concentrations and exposure times. The variations of physiological parameters in grape leaves subjected to controlled soil drought were used as a reference standard. In two independent experiments in 2022-2023, exposure to simulated intense soil drought for three weeks revealed cultivar differences in the ratio of electrolyte leakage and chlorophyll stability index in the test and control cultivars. Similar results were obtained in an experiment on intact grape leaves placed in a 10 % sorbitol solution for 3 hours. It was established that the cultivars ‘Morozko’, ‘Kutuzovsky’ and ‘Dostoiny’ exhibit higher drought resistance compared to the V. vinifera varieties ‘Cabernet Sauvignon’ and ‘Barkhatny’. This approach can be used as a preliminary method for determining the drought resistance of grape cultivars, independently or in combination with fi eld studies.