The Response of Braeburn Apple to Regulated Deficit Irrigation

Abstract

Regulated deficit irrigation (RDI) is one of deficit irrigation (DI) techniques and it is developed to minimize irrigation inputs in fruit production, especially in areas where water resources are limited, is recommended for saving irrigation water in agriculture. This study was conducted to determine the effects of deficit irrigation treatments applied in different growth periods on plant water consumption, water yield relations, stomatal conductance and yield of Braeburn apple variety (grafted on M9 rootstock). Experiments were conducted in the years 2010, 2011, and 2012 at Fruit Research Institute, Eğirdir, Isparta, Turkey. Six different irrigation treatments were applied as I1; non-deficit irrigation program, I2; continuous deficit irrigation program (CDI), I3; deficit irrigation program between the 40th and 70th days after full bloom (DAFB), I4; deficit irrigation program between the 70th and 100th DAFB, I5; deficit irrigation program between the 100th and 130th DAFB and I6; deficit irrigation program between the 130th and 160th DAFB. The highest yield (55.2, 54.1 and 63.8 t ha-1 in 2010, 2011 and 2012 respectively) and water use efficiency (WUE) (0.130, 0.129 and 0.137 t ha-1 mm-1 in 2010, 2011 and 2012) values were obtained from I3 treatment in all short-term deficit irrigation treatments. The stomatal conductance values decreased during the short-term deficit irrigation treatments, but the values increased following the deficit irrigation periods. The results revealed that apple trees grafted on M9 rootstock were influenced by short-term water stress, but they were able to cope with stress after the deficit periods. In all deficit irrigation treatments, yield response factor (Ky) ranged from 0.77 to 2.11 Apple tree yield was less sensitive to water deficit in I3 compared to other treatments. Therefore I3 treatment was found to be applicable in case of scarce water resources since it ensured water saving.