Use of gibberellin to delay maturity and improve fruit quality of ‘French‘ prune

Abstract

SummaryGibberellin (GA) increased firmness of ‘French‘ prune (Prunus domestica L.) when applied preharvest at a rate of 31 or 62 mg 1‒1 in 1997,1998 and 1999. Most effective application dates corresponded with a fruit soluble solids (SS) of 11% to 13% in 1997 and 1998, but with 15% in 1999. The development of SS was temporarily delayed by some of the GA treatments, but was generally similar to the control by harvest time. In 1997, fruit firmness remained higher than the control and extended fruit maturity for up to 7 d by either 31 or 62 mg 1‒1 GA applied at 13% SS, or by 62 mg 1‒1 GA applied at 16% SS. In 1998, fruit firmness was increased by treatment with either 31 or 62 mg 1‒1 GA at 11.5% SS or 31 mg 1‒1 at 16% SS. In 1999, harvest was extended by 3 d due to greater fruit firmness by 31 mg 1‒1 GA applied at 11% or 13% SS, or by 62 mg 1‒1 GA applied at 13% or 15% SS. GA treatments did not affect fruit drop, dried fruit size, or yield. Bloom was delayed by application of GA in 1997 and 1998, particularly with later treatments and with the higher rate. Return bloom in 1998 was not affected by GA treatment in 1997. In 1999,31 mg 1‒1 GA at 11.5% SS resulted in greater return bloom than the control, but bloom of other treatments had similar return bloom as the control. Fruit set was unaffected by the application dates and concentrations tested.