The rate of ethylene evolution of peach fruit (Prunus persica L. Batsch) and ACC content of peach pericarp/mesocarp and seeds was determined during development. Ethylene measurements of whole fruit began 18 days after anthesis (DAA), and ACC quantification was started 32 DAA. ACC levels and ethylene evolution followed similar patterns during stages I and II of fruit growth. At 39 DAA, there was an increase in ethylene evolution and extractable ACC concentration of both pericarp and seeds; however, variability was high at this time. Ethylene evolved by nondeveloping fruit of the “second wave” and “June drop” increased after senescence of the ovule was observed. By 49 DAA, ethylene production and ACC concentration reached a minimum that lasted until a 10-fold increase in ethylene evolution was detected in late stage III. This 10-fold increase in ethylene occurred in four different peach cultivars sampled at “firm-ripe” stage. Seeds excised at 67 DAA, which were incubated for 6 hr in ambient O2 conditions, evolved 400 nl·g−1·hr−1 ethylene and ACC concentration averaged 54 nmol·g−1 fresh weight. It is suggested that in split-pit fruits, ethylene generated by the seeds may accelerate fruit maturation and ripening. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Graduate Research Assistant. Present address: Dept. of Horticulture, Oregon State Univ., Corvallis, OR 97331.
Received for publication 23 Feb. 1987. Contribution no. 7710, Scientific Article no. A-4714 of the Maryland Agricultural Experiment Station, Dept. of Horticulture. We thank Mary Anne McDonough for her assistance in the preparation of this manuscript and Michael Reinsel and Theo Solomos for their aid with the laboratory analyses. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.