Effects of External Ethylene on Laccase and Antioxidant Enzymes Activity,and Physio-Biochemical Characteristics of Potted Miniature Rose cv.Sanaz-e-Zard

In order to study the effect of external ethylene on postharvest display and activity of some senescence-related enzymes in potted miniature roses, this experiment was carried out in a completely randomized design, using three treatment levels with three replications. In glass chambers, potted miniature rose plants were exposed to ethylene concentrations of 0, 5 and 10 μL L-1 for 12 h. The results of study showed that the application of ethylene affected morphological and physiological properties and activity of antioxidant enzymes, as well as laccase enzyme in treated plants. Stress of ethylene in miniature roses caused to increase the percentage of leaf abscission and laccase enzyme activity. Studying defensive mechanism by measuring antioxidant enzymes showed that after using stress of ethylene activity of peroxidase enzyme was gradually decreased. Ethylene concentration of 10 μL L-1 caused to increase activity of peroxidase enzyme in primary days after exposing to ethylene stress but enzyme activity was gradually decreased till the final days. In other side, increasing peroxidation rate of membrane lipids under ethylene stress condition shows plant inability to eliminate or balance oxygen free radicals. Activity of laccase in stressed plants was increased significantly during time, concomitant with decreasing chlorophyll and proline content.