Specificity of gibberellin and sucrose-promoted flower bud growth in gladiolus

Abstract

A critical stage in flower bud growth in the spike of Gladiolus which is initiated by gibberellic acid (GA₃) and sustained by sucrose has been identified. This corresponds to the stage at which separation of the outer bract occurs. In buds at different developmental stages isolated and held in water, it is the same bud stage that first shows increased growth. Buds not induced by light were shown to respond more significantly to GA₃ and sucrose than those induced by light. Since the separation of the outer bract results in light-induced amylase production and starch hydrolysis leading to petal growth, it is proposed that growth promotion by GA₃ is related to light-induced petal growth at this specific stage.