limitations to adopting regulated deficit irrigation in stone fruit orchards: a case study

Fruit production development is resulting in large commercial orchards with improved water management standards. While the agronomic and economic benefits of regulated deficit irrigation (RDI) have long been established, the local variability in soils and climate and the irrigation system design limits its practical applications. This paper uses a case study approach (a 225 ha stone fruit orchard) to unveil limitations derived from environmental spatial variability and irrigation performance. The spatial variability of soil physical parameters and meteorology in the orchard was characterized, and its implication on crop water requirements was established. Irrigation depths applied during 2004-2009 were analysed and compared with crop water requirements under standard and RDI strategies. Plant water status was also measured during two irrigation seasons using stem water potential measurements. On-farm wind speed variability amounted to 55%, representing differences of 17% in reference evapotranspiration. During the study seasons, irrigation scheduling evolved towards deficit irrigation; however, the specific traits of RDI in stone fruits were not implemented. RDI implementation was limited by: 1) poor correspondence between environmental variability and irrigation system design; 2) insufficient information on RDI crop water requirements and its on-farm spatial variability within the farm; and 3) low control of the water distribution network.