Shoot Development in Citrus sinensis L. (Washington Navel Orange). II. Alteration of Developmental Fate of Flowering Shoots after GA₃Treatment

Abstract

Initial stages of inflorescence and vegetative shoot development are described for Citrus sinensis (Washington navel orange). Budbreak occurred in early December, floral initiation in early January, and anthesis in late March. To ascertain when a resting bud was determined as an inflorescence, we treated buds at four stages in development, ranging from resting buds to those producing floral organs, with gibberellin (GA3) in situ. Examination of the shoots at maturity established that GA3 caused complete reversion of the potentially flowering resting buds, partial reversion for buds in early stages of breaking and initiating floral organs, and no significant reversion once the sepals were present. The terminal flower may show reversion to the vegetative state even after a sepal has been initiated, but the lateral buds were determined at initiation to be either thorns or flowers.