Influence of gibberellin treatment on flowering and fruiting patterns in mango

Abstract

The potential for using gibberellins (GAS) to modify time of flowering and fruit maturity in mango was investigated. Winter spraying of mango trees grown in the coastal subtropics of Queensland (latitude 27OS) with gibberellin A3 (GA3) or GA4 solutions caused a delay in flowering time of up to 4 weeks, depending on cultivar (Kensington Pride, Glenn, Early Gold) and concentration (50-200 mg/L). There was also a general reduction in number of panicles, particularly at higher GA concentrations. Similar experiments with GA3 on cvv. Kensington Pride and Keitt in tropical North Queensland (latitude 17¦S) did not show any effect either on time or extent of flowering. Fruit yield was highly correlated with the proportion of terminal buds that flowered. Consequently, GA treatments caused significant yield reductions in cv. Kensington Pride, especially at 200 mg/L where only 23% of terminal buds flowered. Fruit size was inversely related to yield, and yield was influenced by tree size. Delayed flowering also resulted in later fruit maturation, by up to 2 weeks. With Early Gold, late-flowering panicles retained 3 times more fruit than those which flowered early, which was possibly related to differences in night temperatures before or at anthesis. Delays in flowering time, which lead to somewhat lesser delays in fruit maturation, can be achieved with suitable GA treatments, but concentration and timing of application are critical if flowering and, hence, yields are not to be reduced. The potential use of this treatment in commercial mango orchards is discussed in relation to extending the fruit production season.