Effect of integrate water shortage and soil conditioners on water productivity, growth, and yield of Red Globe grapevines grown in sandy soil

Abstract Water-deficit problem in Egypt due to the scarcity of water resources and climatic changes causes significant stress on all crops such as grapevines. Using soil conditioners like superabsorbent polymer (SAP) and Bentonite (BENT) can reduce water problems due to their abilities to store more water and improve the physical and chemical characteristics of soil. A field experiment with a completely randomized block design was carried out in three replicates at a private farm in Minia Governorate, Egypt to assess the influence of SAP and BENT on growth, yield, and water productivity (WP) of Red Globe grapevines as well as some physical and chemical properties of soil under water deficit regime (75 and 50% of water requirement) and full irrigation 100% of water requirement (control) during 2021 and 2022 seasons. The vines were 13 years and irrigated by a drip irrigation system in sandy soil. The studied soil was treated with different doses of SAP (250 and 500 g/vine) and BENT (200 and 400 g/vine). The obtained results showed that reducing irrigation to 75 and 50% of the water requirements led to significant decrease in vegetative growth metrics, readings for SPAD, leaf nutrients (N, P, and K), yield and its constituents as well as the physical and chemical properties of the berries compared to full irrigation. Adding SAP and BENT significantly increase the aforementioned characteristics under water deficit conditions. Application of SAP and BENT was the most effective way to mitigate the negative effects of water shortage on growing Red Globe grapes in sandy soil. SAP gave better results than BENT. Thus, applying superabsorbent 500 g/vine with deficit irrigation 75% of water requirements was a successful treatment in producing an economical yield and berries with fairly high quality and had a positive effect in enhancing WP as well as it proved to be a promising method to improve sandy soil characteristics.