Effects of water stress on fruit quality attributes of kiwifruit

Four-year-old kiwifruit vines (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa cv. Hayward) were studied to determine response of the plant and effects on fruit quality when irrigation water was withheld either early or late in the growing season. The greatest effect on fruit growth occurred when water was withheld early in the season. Harvest weight of fruit from early-stressed vines was approx. 25% less than the weight of fruit on control vines. Early season water stress resulted in a transient increase in concentrations of soluble carbohydrates in both leaves and fruit. This was accompanied by a reduction in stomatal conductance of the leaves. Starch levels in leaves but not fruit were reduced by both stress treatments. Concentrations of sucrose at harvest in fruit from vines stressed late in the season were markedly higher than in other fruit, and softness of the fruit was unaffected. These differences were maintained through the 12 weeks in cool storage after harvest. Withholding irrigation water to kiwifruit vines late in the season may prove a useful management tool to manipulate some quality attributes of the fruit. (C) 1998 Annals of Botany Company.