The effect of methyl jasmonate (MeJA) vapor treatment on antioxidant enzymes activities and vase life ofgerbera cut flower was investigated in this experiment. This research was conducted as a split-plotexperiment based on completely randomized design with three replications at the laboratory of thepostharvest physiology, College of Agriculture, Tarbiat Modares University in 2013. Gerbera flowerswere harvested at early morning from a commercial greenhouse and cut flower stems were put in apreservative solution containing 200 mg/L 8-hydroxyquinoline sulfate and sucrose 3%, exposed to 0, 0. 1, 0. 2 and 0. 3 μ lL− 1 MeJA with 20 μ lL− 1 ethanol and control for 24 h. The results showed that MeJAsignificantly increased vase life and improved postharvest characteristics of cut gerbera flowers. MeJA0. 2 μ lL− 1 treatment extended the vase life to 15. 67 days, compared to the control and ethanol treatments. Minimum of petal wilting symptoms were revealed in samples treated with MeJA. The lowestmalondialdehyde and lipid peroxidation rates were also observed in MeJA treatments that they had asignificant difference with ethanol and control. MeJA treatments resulted in increasing antioxidantenzymes activity and protein content compared with ethanol or control.

Pennyroyal (Mentha pulegium L.) from the Lamiaceae family is a medicinal plant which has great antioxidant properties. Environmental stresses such as drought can result in changes in the activity of antioxidant enzymes and the content of some biochemical factors in plants. In this investigation, the effects of drought stress on the activity of superoxide dismutase, ascorbate peroxidase, catalase, peroxidase, malondialdehyde and soluble sugars content in pennyroyalshoots and roots were evaluated. To create the water deficit, 24-day seedlings of pennyroyal were placed in 1.2 strengthHoagland solution, containing PEG 6000 (0 and 5% (w/v)) for 24 hours. The results showed that drought stress increased catalase activity and lipid peroxidation and decreased superoxide dismutase and peroxidase activity of the shoots.On the other hand, the activity of catalase and peroxidase increased in the roots. Ascorbate peroxidase activity showed no signify cant difference in the shoots and the roots. Moreover, drought stress significantly increased the amount of solublesugars of glucose, galactose, xylose and rhamnosus in the shoots. Therefore, the increased activity in antioxidantenzymes as well as the amount of soluble sugars under drought stress might be a sign of tolerance of M. pulegium underlow levels of drought.