Responses of ‘Bartlett’ Pear to Withholding Irrigation, Regulated Deficit Irrigation, and Tree Spacing

Abstract

Fruit yield was increased, summer pruning decreased, and water saved when regulated deficit irrigation (RDI) and withholding irrigation (WI) were used over 5 years to manage mature ‘Bartlett’ pear ( Pyrus communis L.) trees planted at three levels of within-row spacing (0.5, 0.75, and 1.0 m) and trained to a Tatura trellis. Three levels of irrigation, 23%, 46%, and 92% replacement of evaporation from the planting square (Eps), were compared during the RDI period. Weight of summer prunings was positively and linearly related to level of irrigation in each year, including a relatively wet year. When compared between years, the degree of this response on the dried treatment was positively and significantly related to net evaporation (evaporation – rainfall) recorded during the period of rapid shoot growth. Fruit number also tended to be greater on the 23% and 46% Eps treatments in all years. Cumulative yield over 10 years of cropping did not differ between tree spacing, although fruit size was larger at the 1-m spacing. High yields were obtained at all levels of tree spacing. Yield and tree growth responded most to RDI for the 0.5-m-spaced trees.