Effect of Deficit Irrigation on Quantitative and Quality Traits of Fruit and Water Productivity of Three Grapevine Cultivars

To study the effect of different levels of irrigation on quantitative and quality traits and water productivity of three commercial grapevine cultivars, this research was carried out in stripe block arrangment in randomized complete block design with three cultivares (Qzel-ouzum, Rishbaba and Rasha) and three levels of irrigation treatments (100%, 75% and 50% water requirments) in three replications. At fruit ripenning stage, different traits as weight, length and width of bunch and the quality traits including TSS, TA, pH of the fruit and the volume of the fruit juice were recorded. Combined analysis of variance indicated that different levels of irrigation had significant effect on TSS, TA, pH, juice volume, berry weight and width, bunch width and weight, annual vegetetive growth and fruit yield. The highest and lowest fruit yield were obtained by 100% and 50% irrigation, respectivly. However, effect of 25% deficit irrigation on fruit yield was not significant. Deficit irrigation reduced the juice volume, berry weight and size. Water consumption in 100%, 75% and 50% of water requirments were 4086, 3064 and 2043 m3/ha, respectively. Water productivity of 100%, 75% and 50% irrigation were 2.8, 3.63 and 4.04 kg/m3, respectively. To increase the water productivity in vineyards with optimum fruit yield, application of 25% deficit irrigation is recommended. By decreasing of 25% water use, the water productivity will increase to 30 % without significant reduction in fruit yield. Water productivity was different for groupvine cultivars. cv. Rasha had the highest water productivity.