Plant and fruit responses of lysimeter-grown 'Braeburn' apple to deficit irrigation

Deficit irrigation (DI) at different times during the growing season was investigated for its effects on plant water relations, growth, and fruit quality of 'Braeburn' apple trees grown in lysimeters. Five year old trees on MM.106 rootstock were subjected to three irrigation treatments: well-watered control (C), early deficit-irrigated (ED) from 40 d after full bloom (DAFB) until harvest, and late-deficit irrigated (LD) from 102 DAFB to harvest in a completely randomized design. Both ED and LD trees developed lower soil water content and lower predawn and midday leaf water potential (psi) than C trees. Reduction occurred in trunk diameter growth, return bloom and mean fruit mass for ED fruit. The LD treatment increased the concentration of fruit total soluble solids (TSS), aroma volatiles, and resulted in more mature fruit based on higher ethylene production at harvest and on TSS concentration. Firmness and aroma volatile concentration were greater in LD and ED fruit than in C fruit after 12 weeks of storage at 0 degrees C. Deficit irrigation may be used in apple production to save water while improving fruit quality in terms of increased TSS, firmness in storage, and volatile concentrations without adversely affecting fruit mass. The ED fruit were still in the highest export grade despite 12% reduction in fruit mass.