Regulated deficit irrigation in apricot trees

The aim of this study was to evaluate the response of apricot trees to regulated deficit irrigation strategics. The experiment was performed during four growing seasons (from 1996 to 1999) in ten-year-old apricot trees (Prunus armeniaca L. cv. Bulida), under drip irrigation. Three treatments were applied: a control treatment (T1) irrigated at 100% of seasonal ETc, a continuous deficit treatment (T2) irrigated at 50% of control treatment all year, and a regulated deficit irrigation (RDI) treatment (T3) irrigated at 100% of ETc during the critical periods (second rapid fruit growth period and 2 months after harvest), and a reduction of 40% of ETc during the rest of the non-critical periods. The water amounts applied to the control treatment: was 7254 m(3) ha(-1)year(-1). An average water saving of 34% was achieved in the T3 treatment. Apricot fruit growth showed some differences between the control and the RDI treatment during the deficit irrigation period, but an accelerated rate of growth was noted when irrigation was increased to 100% ETc. During the two first years of the study, when water saving was higher than 40%, total yield obtained in RDI treatment was reduced; however, when irrigation water saving was around 25%, the yield obtained was similar to that of the control treatment. The total yield of the T2 treatment: was significantly reduced in all the years studied. Apricot quality was not modified by RDI treatment, but was affected in the T2 treatment. In consequence, RDI is considered a useful strategy in semiarid areas with limited water resources.