Thinning flat peaches with ethephon and its effect on endogenous ethylene production and fruit quality

Peach orchards are usually hand-thinned at around 40-60 days after bloom, but this practice is labor-intensive and costly. Ethylene plays a key role in peach fruitlet abscission and foliar applications of ethephon have been reported to be effective in some cultivars to induce fruit abscission. However, results are inconsistent and there are no experiences about its application in flat peaches and/or about inducing flowers abscission. Ethephon (from 0 to 300 mg L-1) was applied to 'Flatbeauti' peach trees at 30 % and 100 % of full bloom and 30, 40 and 50 DAFB to determine the best time to induce flowers or fruitlet abscission, as well as to investigate its effect on fruit quality parameters and its relationship to the ethylene evolution pattern throughout peach fruit growth. Abscission and ethylene production were related to ethephon concentration. In general, as a mean of three independent experiments, there was an 8-9 % reduction in fruit set, a 3-14 % increase in fruit size, and a 10-16 % reduction in yield, with each incremental increase of 75 mg L-1 ethephon. The late ethephon applications increased ethylene endogenous production up to harvest and this influenced fruit maturity. Finally, our results indicate that ethephon in the range of 150 mg L-1 can be used at 100 % full bloom and at 30-40 DAFB to induce adequate levels of fruit crop load in `FlatbeautF peaches without other side effects.

Automated summary

The study demonstrates that ethephon can induce fruit or flower abscission in peach trees at specific concentrations and times, affecting fruit yield, size, and quality, as well as being related to the ethylene production pattern.