EVIDENCE FOR THE INVOLVEMENT OF GIBBERELLINS IN DEVELOPMENTAL PHENOMENA ASSOCIATED WITH CARNATION FLOWER SENESCENCE

The application of 10(-4) M GA3 to preclimacteric carnation flowers delayed senescence. climateric ethylene production reduced the rate of loss in fresh weight of intact flowers and the decrease in moisture content or the petals. The loss in flower fresh weight commenced prior to the ethylene climacteric. The increased membrane permeability which was observed when intact, control flowers were half opened, was delayed by GA3 application. This effect was only significant when GA3 was applied to young flowers. In addition to slowing down the loss in fresh mass, GA3 inhibited ethylene production by the style and stigma. The increase in ovary dry weight and chlorophyll content and the associated decrease in petal dry weight was slowed down by GA3 but not arrested, this despite reduced ethylene production by the ovary. It is proposed that a decline in endogenous gibberellin may be a correlative event associated with the onset of the senescence process in carnation flowers.