Gibberellic Acid Increases Fruit Firmness, Fruit Size, and Delays Maturity of ‘Sweetheart’ Sweet Cherry

Abstract

Growers in British Columbia, Canada and the US Pacific Northwest use gibberellic acid (GA ₃) to improve fruit quality of sweet cherries ( Prunus aviumL.). A single spray application of about three weeks before harvest has become the standard procedure. The objective of this trial was to determine if multiple applications of GA ₃can further increase fruit firmness and size, and delay maturity of ‘Sweetheart’ sweet cherry, the second most important sweet cherry cultivar in British Columbia. Yield was not affected by a single application of 20 or 30 ppm or two or three weekly applications of 10 ppm GA ₃in any of the three years of the trial. Fruit treated with GA ₃were significantly firmer than fruit not treated; however, there were no differences in fruit firmness amongst the single or multiple GA ₃treatments. Titratable acidity of GA ₃-treated fruit was significantly higher than that of untreated fruit. There were no differences in titratable acidity within the GA ₃treated fruit. Fruit treated with GA ₃were significantly larger than untreated fruit and the fruit treated with 20 ppm GA ₃were larger than the fruit treated with 30 ppm GA ₃(single applications). In summary, GA ₃-treated fruit could be harvested later and were larger and firmer than untreated fruit. There was no benefit to multiple applications of GA ₃relative to a single application.