Effect of leaf age, duration of cool temperature treatment, and photoperiod on bud dormancy release and floral initiation in mango

Abstract

Floral induction in apical buds of container-grown ‘Tommy Atkins’ mango trees occurred after a cool temperature regime of 18 °C day/10 °C night, 12-h photoperiod, was imposed for a minimum period of 3 weeks on trees bearing leaves at least 7 weeks old. Growth of induced buds during exposure to the cool temperature regime appeared to be necessary for floral initiation, since buds resuming growth in warm temperatures (about 28 °C day/22 °C night) immediately after receiving an inductive, cool temperature treatment produced a vegetative flush. Trees bearing younger leaves or chemically forced (thidiazuron or ammonium nitrate application) to resume growth prior to completing 3 weeks of cool temperature treatment also produced vegetative growth instead of inflorescences. Cool temperatures of 18 °C day/10 °C night with either 11-, 12-, 13-, or 24-h photoperiods resulted in floral initiation, whereas only vegetative growth occurred with warm temperatures of 30 °C day/25 °C night using 11- or 13-h photoperiods. Results of this study suggest that floral induction of ‘Tommy Atkins’ mango occurred during bud dormancy in cool temperatures around 15 °C, and that warm temperatures near 30°C prevented floral initiation of induced buds. Cool temperatures rather than a short photoperiod caused floral induction, whereas warm temperatures rather than a long photoperiod inhibited flowering.