Changes in Content or Release Rate of 4 Kinds of Plant Hormones in Relation to the Development,Ripening and Senescence of Fragrant Pear Fruit

Changes in endogenous IAA,GA 3 and ABA contents and release rate of ethylene of fragrant pear [a variety of bretschneider pear (Pyrus bretschneideri Rehd.)] fruit and the interrelations between 4 kinds of plant hormones were studied during fruit development, ripening and senescence. It was shown that IAA,GA 3 and ABA contents were highest during the early period of fruit development (Fig.2), which favored fruit set. The changes in ABA/GA 3 rate seemed to be the key factor in determining fruit expansion (Fig.3).High GA 3 content obviously inhibited the decomposion of chlorophyll (Fig.2); At the period of fruit maturity, the change in IAA content and the ethylene release rate were along the same direction, the change in GA 3 content was negativly correlated with the ethylene release rate (Fig.5).