Control of Fruit Ripening in Peach, Prunus persica: Action of Succinic Acid-2,2-Dimethylhydrazide and (2-Chloroethyl)Phosphonic Acid

Abstract

Fruits of Halehaven and Fragar peaches (mid- and late season respectively) were sampled and examined weekly during one complete growing season. The period of rapid growth following anthesis (stage I) was characterized by relatively high respiration and ethylene production rates. Fruits of both cultivars entered the subsequent period of slow growth (stage II) together. Ethylene production was low and respiration declined throughout stage II. Sprays of (2-chloroethyl)phosphonic acid (ethephon), but not succinic acid-2,2-dimethylhydrazide (SADH), resulted in increased ethylene evolution by stage II fruits. Neither chemical altered respiration or the duration of stage II. Both chemicals, however, advanced commercial harvest and promoted ripening of fruits sampled throughout the final rapid growth period (stage III). All fruits sampled during stage III showed a climacteric-like increase in respiration and ethylene production. The horticultural effectiveness of SADH and ethephon appears to be due to a promotion of physiological activity in stage III. Abscisic acid in peach pericarp increased just before and during stage III. Possible roles for abscisic acid and ethylene in regulating the stage II-stage III transition in peaches and other fruits are discussed.