COLOR AND PHYSICAL RESISTANCE OF TABLE GRAPES AS AFFECTED BY DEFICIT IRRIGATION AND ZN PULVERIZATION AS ADAPTIVE STRATEGIES TO CLIMATE CHANGE

Abstract

Vineyards are generally located in semiarid and arid zones across the world. Water deficit in these regions adversely affects the grape yield and quality. This experiment was designed to reveal the impacts of deficit irrigation and Zn treatment on berry physical characteristics of Alphonse Lavallée (dark black berries) and Italia (white berries) table grapes under glasshouse condition. Six years old vines were drip irrigated with single emitter of 4 L h⁻¹ per vine to perform full irrigation (FI) or deficit irrigation (DI)] from bud break to the end of the vegetation season in soilless culture. Irrigations were programmed according to soil water matrix potential (Ψm) levels using soil tensiometers. In Alphonse Lavallée, DI treatment resulted in marked decrease in chroma (color saturation; C) in comparison with FI. However, Zn pulverization alleviated the decrease in C and helped to improve the color saturation of DI-subjected Alphonse Lavallée grapes. Similar effect of Zn pulverization on Hue angle of Alphonse Lavallée berries was also obvious. But, there were no significant differences in color coordinates of Italia cultivar in response to treatments. Zn pulverization significantly improved the berry skin rupture force (SRF) of Alphonse Lavallée subjected to FI, although it did not affect those imposed to DI. In Italia cultivar, Zn pulverization significantly increased the SRF of DI grapes. Berry detachment force (BDF) of DI treated Alphonse Lavallée and Italia grapes were significantly improved by Zn pulverization. This case is particularly important for viticulture under water scarcity conditions since berry quality frequently decreases due to shriveling in drought regions. In Alphonse Lavallée cultivar, SRF displayed a significant and strong correlation with BDF. Zn pulverization could be recommended as a sustainable viticulture practice to mitigate the adverse impacts of water deficit on certain table grape quality features.