PETUNIA FLOWER LONGEVITY - THE ROLE OF SENSITIVITY TO ETHYLENE

Two petunia (Petunia hybrida L.) lines, differing in their flower long evity, were studied. Similar tendencies were found in the changes of c orolla fresh weight, electrolyte leakage and membrane microviscosity o ver the life spans of the two lines. Ethylene production by flowers of the two lines showed a similar pattern, peaking at 3 nl flower-1 h-1. However, in flowers of the short-lived line, ethylene production peak ed at 6 days of age, but in the long-lived line, the peak appeared at 10 days of age. A large difference was found in the responsiveness of the flowers to ethylene. Flowers of the short-lived line responded to exogenous ethylene by immediate wilting, while those of the long-lived line responded to a similar ethylene treatment only after two days. D ifferences in sensitivity to ethylene were also observed when the flow ers were treated continuosly with (aminooxy)acetic acid, which blocks ethylene synthesis. Flowers of both lines responded to ethylene treatm ent by increased ethylene production to a similar rate. Differential s ensitivity to ethylene, independent of ethylene production, seemingly governs flower longevity in the two petunia lines studied.