PHYSIOLOGICAL, VEGETATIVE, AND PRODUCTION RESPONSES OF PEACH TO SUSTAINED DEFICIT IRRIGATION

Low rainfall and poor rainfall in recent years in Morocco, have led to a situation of water deficit throughout the cropping cycle, including stone fruits. The study was carried out to investigate the behavior of peach trees under sustained deficit irrigation (SDI) in the Sais plain as well as to determine the optimal irrigation dose that would guarantee an improvement in productivity and quality of the peach trees. This experiment used completely randomized design with 3 replications. The study was carried out (in two replications in 2017 and 2018) four water regimes throughout the whole development cycles of peach trees: T0 (equal to or greater than 100% of the crop's Evapotranspiration (ETc)), T1 (100% ETc), T2 (80% ETc) and T3 (60% ETc). The response of trees is presented for physiological indicators – vegetative development, production and quality parameters for the two years. The effect of SDI on peach trees showed that water restrictions varied according to the water regime. The decrease in irrigation rate negatively affected the main vegetative and production parameters. However, for the 20% decrease in irrigation rate, the effect on yield was not significant. Regarding vegetative growth, the T3 (60%ETc) water regime significantly affected the increase in length and diameter of the current year's shoots, while the T2 (80 % ETc) water regime did not affect leaf area. Trees from treatment T3 (60 % ETc) yielded fruits with the highest sugar content. This increase in sugar content was accompanied by a decrease in the total acidity of the fruit juice.