Abstract

Fruit yield and quality of 4 year old “Williams Pride” apple trees on M9 rootstock under partial rootzone drying (PRD) were studied over 2 years. Irrigation treatments were control irrigation (CI), conventional deficit irrigation (DI), and two different partial rootzone drying (PRDI and PRDII). In PRD, irrigation water was applied alternately on one side of the tree’s rows and the other side was not irrigated. While the irrigated side was changed at every irrigation in PRDI, the side that was not irrigated was changed at every other irrigation in PRDII. Total irrigation water amount was 324.1 and 314.2 mm for CI in 2009 and 2010, respectively. Applied irrigation water amount for DI, PRDI and PRDII was 50% of the CI. The ranking of water use efficiency (WUE) and irrigation water use efficiency (IWUE) values was maintained as PRDII>PRDI>DI>CI in average, in 2009 and 2010. Consequently, minimal or no differences between PRDII and CI treatments were determined in vegetative growth, some yield components and fruit quality. These results recommended that PRD treatments are more effective water saving irrigation technology with a higher WUE and not reduce fruit quality for apple trees compared to regulated deficit irrigation.

Key words: Apple, yield, irrigation water, partial rootzone drying, water use efficiency.