The relationsships between fruit drop induced by seed injury and seed development were investigated in “Beni Shimizu” peach. Seed injury(Injury) was done by drilling from opposite side of suture line upto seed coat using an electric drill(outre diameter of 2.5mm) at 40, 50, 60, 72 and 80 days after full bloom(DAFB). Injections of gibberellic acid(GA) and paclobutrazol(PBZ) (Injection), which relate to fruit drop and seed development were carried out just after the injury for seed. In all of the Injury and Injection treatments, treated fruit dropped in 40, 50 and 60 DAFB treatments but not in 72 and 80 DAFB treatments. Weight of fruit and seed debreased rapidly at 3 days after treatment(DAT) in 60 DAFB treatment. Morphology of endosperm and embryo was compared among 60, 72 and 80 DAFB treatments. Growth of endosperm and embryo stopped from 3 DAT in 60 DAFB treatment but embryo continued to grow until 5 DAT in 72 DAFB treatment. Collapsed cell nucleus in endosperm and embryo occurred at 3 DAT in 60 DAFB treatment. On the other hend, in 72 DAFB treatment cell nuclei in endosperm collapsed in a similar manner as in 60 DAFB treatment although the cell nuclei in embryo did not collapse. When morphology of chalazal haustorium in 60 DAFB treatment was examined, chalazal haustorium began to shrink just after the treatment and percentage of seed with normal chalazal haustorium decreasedrapidly in all treatments. Based on these results, the process of seed abortion as a result of seed injury and its relationship between embryo growth and fruit drop is discussed.
injection of gibberellic acid