2019 ASHS Annual Conference

Peach (Prunus persica L.) is a deciduous crop, commonly grown in temperate regions. Its cultivation and production are rapidly increasing in Florida as growers are looking for alternative tree fruit crops. Peach tree requires the temperature of less than 7.2⁰C for chilling hour accumulation (required accumulation differs among varieties). It is critical for the peach to undergo dormancy (inhibition of cell proliferation and shoot growth) for onset of successful commercial and uniform fruit production for next season. Abscisic acid (ABA) plays an important role in regulation of bud dormancy. On the other hand, use of hydrogen cyanamide (HC), is well known to help in breaking bud dormancy under mild winter conditions. Therefore, main objective of this study is to evaluate the efficacy of exogenously applied ABA inducing dormancy, under low-chill conditions. Four treatments were evaluated on two peach cultivars, ‘UFBest’ and ‘UFSun’. The experiment was set up as completely randomized design (n=4). The four applied treatments were: Untreated control; ABA (500 ppm/tree, 2 application, made three weeks apart in November); HC (1.2%) applied in late December; ABA+HC. All the treatments included with 0.125% surfactant. Leaf emergence, swollen bud, bud break, and flower were counted at every 15 days interval. Interestingly, first application of ABA resulted in complete defoliation in both varieties. In both varieties, ABA resulted in delay in bud swelling and flowering by at least 15 days. Use of ABA with HC resulted in highest and uniform flowering than HC alone in UFBest cultivar. This effect is most likely due to the fact that, HC application resulted in abscission of buds at advanced stage however, pretreatment of ABA potentially induced dormancy thereby decelerating the bud advancement. These field results will be paralleled with in depth- transcriptomic and metabolic analysis to validate and explore dormancy induction and dormancy break in low-chill peaches with use of plant growth regulators.