Effects of regulated deficit irrigation on physiology and fruit quality in apricot trees

The effects of regulated deficit irrigation (RDI) were studied on 9 year-old apricot-trees (Prunus armeniaca L. cv. ‘Búlida’) grafted on ‘Real Fino’ rootstock. Two irrigation treatments were established. The first, a control treatment, was irrigated to fully satisfy the crop water requirements (100% ETc) and the second, a RDI treatment, was subject to water shortage during the non-critical periods of crop development, by reducing the amount of applied irrigation water to: a) 40% of ETc from flowering until the end of the first stage of fruit growth; b) 60% of ETc during the second stage of fruit growth and c) 50% and 25% of ETc during the late postharvest period (that starts 60 days after harvesting), for the first 30 days and until the end of tree defoliation, respectively. The results indicated that the apricot tree is an appropriate species to apply RDI thanks to the clear separation between their vegetative and reproductive growths and its ability to recover the fruit diameter reduction suffered during RDI application. Furthermore, some qualitative characteristics such as the level of soluble solids, fruit taste and the colour of the fruit are enhanced. These two reasons, together with irrigation water savings of 39%, emphasize the RDI strategies as a possible solution in areas with water shortages, like the south-eastern region of Spain. Additional key words: fruit growth, photosynthesis; Prunus armeniaca L.; regulated deficit irrigation; stomatal conductance; water relations; water stress.