Effect of post-veraison deficit irrigation on berries yield, quality and water use ‎efficiency of grape cvs‏.‏‎ Keshmeshi and Sahebi ‎

In this study, the effect of different post-veraison deficit irrigation treatments on yield and berry quality of grape cvs. ‘Keshmeshi’ and ‘Sahebi was evaluated in a split plot experiment with a randomized complete block design. The treatments were control, irrigated at 100% of crop evapotranspiration (ETc), and deficit irrigation at 80, 60 and 40% of control during post-veraison till harvesting. Results showed that no significant difference was found between control and 80 deficit irrigation for berry yield, mean berries and cluster weight, but deficit irrigation at 60 and 40 % decreased berry yield up to 22 and 37%,  respectively as compared to control. The deficit irrigation at 40% increased TSS in Keshmeshi, but in Sahebi cultivar, deficit irrigation resulted to decrease TSS. Furthermore, deficit irrigation also decreased TSS to TA ratio. The highest phenolic content, which found in Keshmeshi and Sahebi cultivars at 80% deficit irrigation was 60 and 40% more than control. The antioxidant activity of Keshmeshi and Sahebi cultivars was increased 45 and 34% as compared to control with 80 and 40% deficit irrigation. Deficit irrigation at 80% of control could save water up to 20%, without reducing water use efficiency. In general, 80% deficit irrigation might be sufficient to maintain yield potential of Keshmeshi and Sahebi cultivars, without significant loss in grape quality.