Physiological response to drought and heat stress in the leaves of table grape varieties

Abstract

Increasingly pronounced climate changes, including prolonged drought periods, pose a significant challenge to the cultivation of table grape varieties. These varieties are particularly vulnerable to water shortages, which adversely affect their yield, market quality, and sustainability of table grape farming. To ensure long-term sustainability, it is essential to prioritize varieties with greater resistance to drought and high temperatures. In-depth studies of table grape responses to drought conditions provide critical insights into plant adaptive mechanisms, enabling the implementation of advanced cultivation techniques in drought-affected regions. Expanding knowledge of the physiological, chemical, and genetic responses of these varieties directs to more sustainable and resilient table grape production in the future. The physiological response to drought and heat stress in the leaves of table grape varieties was investigated. The study took place in 2024 at the University of J.J. Strossmayer in Osijek, viticulture experimental station Mandićevac, within a collection of table grape varieties. No differences among grape varieties were observed in the concentration of chlorophyll a, chlorophyll b, chlorophyll a+b, carotenoids, and total phenols. A significant difference (p < 0.05) was observed in proline concentration and ferric-reducing antioxidant power (FRAP). The highest proline concentration was observed in the “Sindikat” variety, while the lowest was identified in “Sonja”. However, the significantly highest FRAP was determined in the “Sonja” variety, while the lowest activity was in “Suzi”. Regardless the cultivar Sonja is not prone to accumulate free proline, considered one of the key regulators of osmotic potential in drought stress conditions, the elevated antioxidant activity indicates that other physiological mechanisms, such as increased phenol synthesis, may be involved in defence against high temperatures and drought.