Deficit-irrigation management for sustainable grape production (Vitis vinifera L.): different regimes to assess yield and berry quality under arid conditions.

Water scarcity is one of the main obstacles to agricultural development, particularly in Egypt. Grapevines are sensitive to drought and therefore depend heavily on improved irrigation regimes. It could be a crucial approach for the agricultural development of any country. This study evaluated the effect of deficit irrigation regimes on the growth, productivity, and cluster quality of the Flame seedless grapevines during two successive seasons (2024 and 2025) at a private orchard in the Luxor Governorate, Egypt. Grapevines were distributed in a completely randomized block design (CRBD) with three irrigation treatments and three replicates of each: (T1)—100% of crop water requirements (CWR), serving as the control; (T2)—80% of CWR; and (T3)—60% of CWR. The results indicated that vines receiving 80% CWR had a yield decrease of 3.70% compared to full irrigation; however, the amount of water saved throughout this process compensated for the lower yield, thus it did not have a significant overall impact. The irrigation treatment had an impact on all of the cluster’s assessed physicochemical characteristics, with irrigation at 80% CWR being the best strategy for reducing water consumption and enhancing cluster quality. By balancing resource conservation, productivity, and quality, 80% CWR represents a viable solution to meet the dual challenges of sustainable agriculture and water scarcity.