Maximum daily trunk shrinkage for estimating water needs and scheduling regulated deficit irrigation in peach trees

Water scarcity and increasing water use in many socioeconomic sectors lead to an urgent need to improve irrigation management, especially in arid and semiarid areas, such as southeast Spain. For this reason, we studied, during 3 years, the possibility of scheduling regulated deficit irrigation (RDI) using maximum daily shrinkage (MDS) measurements on peach trees [Prunus persica (L.) Batsch cv. “Catherine”] in Murcia (Spain). Three irrigation treatments were established: a control treatment (CET0), irrigated above the estimated crop water requirements, and two treatments based on measurements of maximum daily trunk shrinkage signal intensity (MDS SI), namely a precision treatment (CMDS) using a threshold value of MDS SI = 1 during all the period and a RDI treatment using MDS SI = 1 all the period except for stage II and post-harvest where MDS SI = 2. The low coefficients of variation for MDS SI indicated that this information was sufficient to adjust the irrigation schedule to maintain MDS SI close to the selected threshold values. Maintaining the MDS SI close to unity throughout the growing season allowed us to estimate peach water requirements (ETc). The RDI treatment significantly reduced pruning weight, but no differences were found in terms of reproductive growth and yield. Moreover, RDI increased water productivity and fruit quality, since soluble solids content and maturity index were higher in the RDI treatment compared to CET0 and CMDS. This study demonstrated that irrigation scheduling in peach trees based exclusively on MDS SI was feasible without detrimental effects on yield and fruit quality.