Kaan Kurtural,* Clinton Nelson, Luca Brillante, and Shijian Zhuang Zhuang 
*University of California, 1380 Oakville Road, Oakville, CA 94562
(skkurtural@ucdavis.edu)

A field trial was conducted in the hot climate of central California to assess the interactive effects of production systems and applied water on canopy architecture, yield, water footprint, and berry composition of Zinfandel. Production systems were split-canopy, cane-pruned (CP, six-canes with eight nodes), spur-pruned (SP, 22 two-node spurs), and mechanically box-pruned single high-wire (MP, 100 mm hedge). Applied water treatments were sustained deficit irrigation (SDI), receiving 80% of crop evapotranspiration (ETc) from budbreak to leaf fall, and regulated deficit irrigation (RDI), receiving 80, 50, and 80% of ETc between budbreak and fruit set, fruit set to veraison, and veraison to leaf fall, respectively. The vineyard received 87, 30, and 46% of the 10-year average of winter precipitation in years 1, 2, and 3 of the study. The Yl of SDI was consistently greater, while production systems did not affect it. The yield of SP and CP declined consistently while MP did not. The leaf area to fruit ratio of MP in combination with SDI was maintained at 0.70 m2/kg, while SP and CP varied greatly during the study period. RDI reduced the water footprint of Zinfandel regardless of production system, but the associated decrease in yield was not commercially acceptable. The water foot print of MP was 22% less than traditional production systems. Our results provide evidence that the combination of MP and SDI is a sustainable production system based on sustained yield, optimum leaf area to fruit ratio, and reduced water footprint in a hot climate.

Funding Support: American Vineyard Foundation