EVOLUTION OF ENDOGENOUS GIBBERELLINS AT DIFFERENT STAGES OF FLOWERINGIN RELATION TO RETURN BLOOM OF CACTUS PEAR (OPUNTIA-FICUS-INDICA L. MILLER)

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 determin ed. Throughout the bloom period, the concentration of GA(3) was higher in intact flowers and the cladode that in flowers emasculated or inje cted with paclobutrazol. With the onset of blooming, GA(3) started to accumulate both in the flower and in the fertile cladode, and the high est concentration was measured at full bloom in the flower nad in the cladodes whose flowers were not removed. Flower emasculation or remova l similarly affected GA(3) concentration at any stage of bloom. Until petal shedding GA(3) concentration was higher in the flowers than in t he fertile cladodes. Consistent return bloom occurred only when the sp ring flush was removed before bloom. Fruit resulting from flowers emas culated or treated with paclobutrazol had a smaller size, percent fles h and seed content than fruits produced by untreated flowers. (C) 1998 Elsevier Science B.V.