Hormonal regulation of flower senescence in roses (Rosa hybrida L.)

To elucidate the role of the plant hormones-abscisic acid (ABA) and ethylene during flower senescence in roses, experiments were conducted on two cultivars of cut-roses (Rosa hybrida L.), 'Grandgala' and 'First Red,' obtained from a commercial grower. An apparent similarity was observed during flower senescence and accumulation of endogenous ABA in petal tissue. Several fold increase in ABA concentration was observed during the later stages of senescence which was found to be associated with a drastic reduction of flower water potential and water uptake. During the later stages of senescence (S5-S6) higher ABA concentration coincides with the elevated concentration of ethylene production. ABA and ethylene both stimulate senescence and are suggested to interact during flower senescence under water limitations.