Enhancing Water Use Efficiency and Berry Ripening in Cabernet Sauvignon: Effects of Irrigation Regimes and Biostimulants
Alessandro De Rosa, Luca Pallotti, Eve
Laroche-Pinel, William Whalen, and Luca Brillante*
*Department of Viticulture and Enology, California State
University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740
(lucabrillante@csufresno.edu)
Water availability is a key factor for agriculture, as rising temperatures increase plants’ water demand, while water resources become increasingly limited.
Optimizing water use efficiency is essential to enhance vine tolerance to heat stress and ensure high productivity. This study examines the effects of four distinct irrigation regimes: vines irrigated at 50, 75, and 100% of estimated crop evapotranspiration (ETc), alongside regulated deficit irrigation (RDI), employing 50% of vine ETc from fruit set to veraison and 100% from veraison to harvest, both independently and in combination with a biostimulant during the 2023 growing season. Measurements were taken for stem water potential, gas exchange, berry ripening, and yield at harvest of Cabernet Sauvignon vines. The biostimulant did not affect vine physiology, as stem water potential, gas exchange, and water use efficiency remained unchanged between treated and untreated vines. There were differences related to irrigation amount, with greater water supply leading to lower stress conditions and increased photosynthetic activity. However, this improvement came at the cost of reduced water use efficiency when compared with the 50% irrigation and RDI treatments, which had the greatest efficiency. The biostimulant increased berry and cluster weight without affecting berry ripening in combination with 50, 75, and 100% irrigation, but not with RDI. The water regime had a significant effect on juice composition, with the 50% treatment hastening berry ripening and the 100% treatment delaying it. Interestingly, RDI had the most pronounced effect on ripening, slowing down sugar accumulation and preserving organic acids.
Even though the effects of the biostimulant were limited, this study underscores that restricting water during periods when vine demand is limited represents a sustainable approach to enhance water use efficiency and delay berry ripening.
Funding Support: N/A
