Evolution of endogenous gibberellins at different stages of flowering in relation to return bloom of cactus pear ( Opuntia ficus-indica L. Miller)

Abstract

The effect of flower emasculation, flower injection with paclobutrazol and the complete removal of the spring flush of flowers and cladodes on the changes in GA 3 concentration at different stages of bloom in flowers and fertile cladodes of Opuntia ficus-indica has been determined. Throughout the bloom period, the concentration of GA 3 was higher in intact flowers and the cladode than in flowers emasculated or injected with paclobutrazol. With the onset of blooming, GA 3 started to accumulate both in the flower and in the fertile cladode, and the highest concentration was measured at full bloom in the flower and in the cladodes whose flowers were not removed. Flower emasculation or removal similarly affected GA 3 concentration at any stage of bloom. Until petal shedding GA 3 concentration was higher in the flowers than in the fertile cladodes. Consistent return bloom occurred only when the spring flush was removed before bloom. Fruit resulting from flowers emasculated or treated with paclobutrazol had a smaller size, percent flesh and seed content than fruits produced by untreated flowers.