Fruit nutritional quality under deficit irrigation: the case of table grapes in California

BACKGROUND: Sustainable agricultural practices are needed to face current threats to agricultural production in areas where water scarcity, recurrent droughts, and decreased soil quality are endangering productivity and food security. Deficit irrigation (DI) practices consist of reducing irrigation applied at levels below full crop evapotranspiration losses throughout the growing season or at specific phenological stages of the specific crop. The goal of our study was to evaluate the physiological response of table grapes subjected to DI relative to fruit quality. DI treatments were developed as a percentage of the grower practice (evapotranspiration losses are fully replenished by irrigation) on commercial fields of table grapes in central California. DI practices began in 2011 and were continued throughout 2015. Grape berries were analyzed for mineral elements, berry weight, diameter and firmness, carbon and nitrogen content, pH, soluble solids, and total phenolic compounds. 

RESULTS: In this study, DI practices in all treatments did not significantly increase or decrease nutraceutical compounds in grape berry and measured physiological responses to DI were mixed, with significant variation between years. 

CONCLUSIONS: This study showed that DI practices could be safely used in dry areas for at least four years without affecting the nutritional quality of grape berry in ‘Crimson seedless’ and ‘Sugraone’.