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Impact of Exogenous Melatonin Foliar Application on Physiology and Fruit Quality of Wine Grapes under Salt Stress.

Yuanyuan Li, Congcong Zhang, Xu Lu, Haokai Yan, Guojie Nai, Meishuang Gong, Ying Lai, Zhihui Pu, Li Wei, Shaoying Ma, Sheng Li

Abstract

Soil salinization is an important abiotic stress faced in grape cultivating, leading to weakened plant vigor and reduced fruit quality. Melatonin as a novel hormone has shown positive exogenous application value. Therefore, this study used wine grape 'Pinot Noir' as a test material to investigate the changes of foliar spraying with different concentrations of melatonin on the physiology and fruit quality of wine grapes in a field under simulated salt stress (200 mmol·L⁻¹ NaCl). The results showed that foliar spraying of melatonin significantly increased the intercellular CO₂ concentration, maximum photochemical quantum yield of photosystem Ⅱ, relative chlorophyll and ascorbic acid content of the leaves, as well as the single spike weight, hundred-grain weight, transverse and longitudinal diameters, malic acid, ɑ-amino nitrogen, and ammonia content of fruits, and decreased the initial fluorescence value of leaves, ascorbate peroxidase activity, glutathione content, fruit transverse to longitudinal ratio, and tartaric acid content of plants under salt stress. The results of the comprehensive evaluation of the affiliation function indicated that 100 μmol·L⁻¹ melatonin treatment had the best effect on reducing salt stress in grapes. In summary, melatonin application could enhance the salt tolerance of grapes by improving the photosynthetic capacity of grape plants under salt stress and promoting fruit development and quality formation, and these results provide new insights into the involvement of melatonin in the improvement of salt tolerance in crop, as well as some theoretical basis for the development and industrialization of stress-resistant cultivation techniques for wine grapes.

FP24019  Accepted 26 April 2024

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