Irrigation Management Based on Theoretical Requirements Reduces Water Consumption in Apple (Malus domestica Borkh.) Orchards without Effects on Fruit Yield and Components

This research examines the effects of two irrigation strategies on water use efficiency and fruit yield components of 'Royal Gala' and 'Brookfield Gala' apple orchards in south-central Chile. The study was carried out during the 2008-2009 and 2009-2010 growing seasons at two sites. A randomized block experimental design was established with two water application treatments: theoretical volume required by the plant (T1) and farm protocol (T2). Soil water content, plant water potential and yield components were evaluated. The soil water content in T2 was near field capacity while T1 was between the permanent wilting point and field capacity for both seasons and varieties. With T1, the seasonal volume applied was 21 to 28% less compared to T2, with season savings of 1600 m(3) ha(-1). No effect on plant water potential was observed. In 'Royal Gala' the lower volume applied in T1 did not lead to significant differences in fruit diameter, weight, or yield in either season as compared to T2. In 'Brookfield Gala', yield during the 2008-2009 season increased significantly, by 22.9% in treatment T1, and in the 2009-2010 season, significant reductions (p < 0.05) in fruit diameter (5.3%) and weight (12.9%) were observed in T2. Productivity per volume of applied water in T1 was 32% to 56% greater than that obtained with T2. The results show the effectiveness of the irrigation strategy considering the theoretical volume of water required by the plant.