The influence of gibberellic acid, 2,4-dichlorophenoxyacetic acid and 6-benzylaminopurine on fruit-set of Clementine mandarin

A study was made of the influences of gibberellic acid (GA₃), 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA) on leafy inflorescences — and of GA₃ on entire trees — on fruit-set and fruit-weight of Clementine mandarin (Citrus reticulata Blanco).Applying GA₃ to inflorescences of cultivar ‘Fino’ (seedless Clementine) between anthesis and 14 days after anthesis increased fruit-set and weight of the fruits at harvest. No significant differences in effects were observed between the application to leaves, to flowers or to leaves and flowers simultaneously. GA₃ induced the development of parthenocarpic fruits of cultivar ‘Monreal’ (Clementine with seeds) and a fruit-set similar to that obtained with self-pollination. Spraying GA₃ (5–200 mg/l) to entire trees of cultivar ‘Fino’ increased the number of fruits per tree and decreased the average weight of the fruits. However, the commercial yield per tree increased with the concentration of GA₃ employed.The application of 2,4-D and BA to inflorescences of cultivar ‘Fino’ increased fruit-setting and weight of the fruits, although not as efficiently as GA₃, both the concentration and the time of application being more critical.