Regulation of Cropping and Fruit Quality of Conference Pear by the Use of Gibberellic Acid and Thinning. II. The Effect of Ethephon as a Flower Thinner When Used in Conjunction with Gibberellic Acid Application

Abstract

SummaryThe number of fruits developing on Conference pear trees treated at flowering with gibberellic acid was reduced by the application of ethephon, and the amount of large fruit increased. Although time of application, from white bud (pre-GA3) to petal-fall, did not influence the response to ethephon, both temperature and the concentration of GA3 affected the response considerably. Although increasing the alkalinity of an aqueous ethephon solution compensated for low temperatures, in terms of the amount of ethylene released into an enclosed space, the result of using this technique with a field spray was inconclusive. The mechanism of action of ethephon as an abscission agent in relation to its breakdown characteristics is discussed.