Effects of partial rootzone drying and conventional deficit irrigation on yield and quality parameters of “Williams Pride” apple cultivar drafted on M9 rootstock

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.