Gibberellin and temperature effects on dormancy release and shoot morphogenesis of mango (Mangifera indica L.).
Núñez-Elisea R., Davenport T. L.
Author Affiliation: University of Florida, IFAS, Tropical Research and Education Center, 18905 SW 280th St, Homestead, FL 33031, USA.
Scientia Horticulturae 77 : 11-21
Abstract : Single foliar sprays of gibberellic acid (GA3) (10-250 mg litre-1) were applied during cool or warm temperatures to determine their effects on shoot initiation and morphogenesis in mango cultivars Keitt and Tommy Atkins. Dormant, non-differentiated axillary buds were released by removing the apical inflorescence (deblossoming) in flowering shoots, or by heading the terminal vegetative flush (intercalary unit) in vegetative stems. Buds of non-treated and GA3-treated stems initiated growth during exposure to cool (about 26°C day/15°C night outdoors in southern Florida or 18°C day/10°C night in a growth chamber) or warm temperatures (outdoors at about 29°C day/25°C night or 30°C day/25°C night in a growth chamber). Buds initiated inflorescences despite GA3 treatment when morphogenesis occurred during exposure to cool, flower-inductive temperatures outdoors or in the growth chamber. A single GA3 treatment delayed initiation of inflorescences on deblossomed orchard stems, but not on headed vegetative stems. GA3 treatment resulted in vegetative shoot production only when buds differentiated during exposure to warm temperature conditions either outdoors or in a growth chamber. Thus, GA3 delayed inflorescence initiation but did not cause vegetative morphogenesis when bud differentiation occurred in cool temperatures. In contrast to delaying inflorescence initiation in cool temperatures, GA3 did not delay vegetative growth during warm temperatures. Thus, it is concluded that GA3 prevents initiation of reproductive shoots of mango rather than inhibiting flower induction.