Study of drought and heat resistance in fruit crop varieties under changing climate conditions (on the example of sweet cherry in Krasnodar Krai)

Abstract

An important area for improving the effectiveness of agri-food systems under stress conditions is the selection of highly drought- and heat-resistant varieties. The present study aims to develop new approaches to the evaluation of these characteristics, taking into account the ability of varieties to successfully pass through the stages of fruit bud differentiation at high summer temperatures, without their development being suppressed. An analysis of climatic conditions in the Kuban horticultural zone of Krasnodar Krai for 1989–2022 revealed the occurrences of temperatures above +30...+35 C that suppress fruit bud differentiation in fruit crops, thus indicating the need for new data on the stress response of varieties. The variability structure of drought resistance indicators was studied using data for three years (2019, 2021, and 2022): tissue water content and leaf water-holding capacity in sweet cherry varieties grafted on VSL-2, including those bred by an institute (‘Slavyanka’, ‘Kavkazskaya’, ‘Kavkazskaya Uluchshennaya’, ‘Volshebnitsa’, and ‘Alaya’). Their high dependence on seasonal conditions was established. The effect of high temperatures on fruitbud differentiation in cherry varieties was evaluated. The adaptability of plants and varieties to the lack of moisture and high summer temperatures was noted to be inextricably linked. The focus was on a comprehensive approach to evaluating drought and heat resistance in the selection of the best sweet cherry forms that are able to develop normally and set fruitbuds at high temperatures. The latter characteristic should be taken into account when entering varieties into the State Register of Breeding Plantations to establish the possible cultivation limits of the proposed plants and to create new varieties having a higher resistance to temperature stresses. Drought and heat resistant sweet cherry genotypes capable of tolerating summer stresses and regularly yielding crops were identified. The following varieties were found to be resistant to high temperatures: early ripening period – ‘Kavkazskaya’ and ‘Slavyanka’; average ripening period – ‘Volshebnitsa’, ‘Kosmicheskaya’, and ‘Summit’; late ripening period – ‘Alaya’ and low-growing clone of ‘Drogana Zheltaya’.