Seasonal Susceptibility of Grapefruit to Chilling Injury as Modified by Certain Growth Regulators1

Abstract

Abstract Changes in susceptibility to chilling injury of grapefruit ( Citrus paradisi MacF.) were found to vary directly with the growth activity of the trees. Exogenous growth regulators were applied to test the hypothesis that they may be involved in seasonal variations in susceptibility to chilling injury. Benzyladenine, gibberellic acid and 2,4-dichlorophenoxyacetic acid applied postharvest and benzyladenine and 2,4-D applied preharvest significantly altered susceptibility to chilling injury although the direction and extent of the changes were neither consistent nor predictable.