Porat, R., The Kennedy-Leigh Centre for Horiticultural Research, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
Reuveny, Y., The Kennedy-Leigh Centre for Horiticultural Research, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
Borochov, A., The Kennedy-Leigh Centre for Horiticultural Research, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
Halevy, A.H., The Kennedy-Leigh Centre for Horiticultural Research, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel

Two petunia (Petunia hybrida L.) lines, differing in their flower longevity, were studied, Similar tendencies were found in the changes of corolla fresh weight, electrolyte leakage and membrane microviscosity over 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 peaked 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 flower to ethylene, Flowers of the short‐lived line responded to a similar ethylene by immediate wilting, while those of the long‐lived line responded to a similar ethylene treatment only after two days. Differences in sensitivity to ethylene were also, observed when the flowers were treated continuosly with (aminooxy)acetic acid, which blocks ethylene synthesis. Flowers of both lines responded to ethylene treatment by increased ethylene production to a similar rate. Differential sensitivity to ethylene, independent of ethylene production, seemingly governs flower longevity in the two petunia lines studied. Copyright © 1993, Wiley Blackwell. All rights reserved