Effects of gibberellic acid, ethephon or girdling on the production of racemes in Macadamia integrifolia

Abstract

The effects of gibberellic acid (GA 3), ethephon or trunk girdling on raceme production and fruit set of Macadamia integrifolia Maiden & Betche, Proteaceae, when applied at the onset of the flowering season were evaluated. A single application of GA 3 at 200 or 1000 mg l −1 inhibited flower production. Trees treated with 100 or 500 mg l −1 ethephon had an earlier first flowering peak and a reduction in racemes with fruit set per tree. Girdling increased the cumulative number of racemes with unopened flower buds and with flowers at anthesis when counted at 2-week intervals during the flowering season. This resulted in an increase in racemes with fruit at the conclusion of the flowering season.