Studies on Abscission of Phthalimide-induced Parthenocarpic Sour Cherry Fruits

Abstract

AC 94377 (alone and in combination with an auxin), GA3, and BA were evaluated for induction of parthenocarpy and subsequent retention of sour cherry (Prunus cerasus L. ‘Montmorency’) fruit. The persistence of AC 94377-treated fruit was enhanced by addition of CFPA or NAA, persistence and growth being greatest with AC 94377 (3.0 × 10−3 m) + CFPA (7.5 × 10−5 m). CFPA alone (7.5 × 10−5 m) often prevented abscission of flowers, but failed to induce significant fruit growth. Parthenocarpic fruit weighed 30-40% less than seeded fruit. Abscission of parthenocarpic fruit occurred primarily during June drop, and was reduced by an additional application of AC 94377 + CFPA with or without GA3 3 weeks after bloom. AC 94377 and NAA sprayed 2 and 3 weeks after full bloom did not affect the magnitude of June drop of open-pollinated fruit. The rate of fruit abscission was related to time after application, presence or absence of seeds, and relative position between seeded and parthenocarpic fruit. When AC 94377, GA3, and CFPA were applied in lanolin paste to defruited pedicels, only mixtures including CFPA reduced the abscission rate significantly. Chemical names used: l-(3-chlorophthalimido)-cyclohexanecarboxamide (AC 94377); 2-chloro,4-fluorophenoxyacetie acid (CFPA); N-(phenylmethyl)-lH-purin-6-amine (BA); gibberellic acid (GA3); 1-naphthaleneacetic acid (NAA).