Effect of melatonin on enzyme activity and salinity tolerance of calendula (Calendula officinalis L.) based on the evaluation of morphophysiological characteristics

Salinity stress is one of the most important limiting factors for plant growth. The marigold plant has many uses in green space design. Melatonin is a natural antioxidant that moderates the negative effects of salinity stress in plants. The present study was conducted in order to investigate the effect of melatonin pretreatment on enzyme activity and morphophysiological characteristics of marigold under saline water irrigation conditions. This research was done in factorial form in a completely randomized design with three replications. The treatments included melatonin at three levels (zero, 100 and 150 µM) and saline with sodium chloride salt at four levels (zero, 30, 60 and 90 mM). According to the obtained results, the activity of catalase and guaiacol peroxidase in plants pretreated with 150 μM melatonin under 60 mM salinity (0.094 g/fresh weight) and 150 μM melatonin in 30 mM salinity (0.157 g/fresh weight) was at its maximum. The highest amount of protein (35.36 mg/fresh weight) was recorded in plants treated with 150 μM melatonin without salt treatment. The increase in catalase enzyme, guaiacol peroxidase and protein compared to the control was 84.31, 300 and 11.83%, respectively. The number of flowers in 100 and 150 micromolar melatonin treatments without stress was the highest (2 number). The increase in the number of flowers, plant height, fresh weight, and dry weight of aerial parts compared to the control was 20.48, 60.03, 17.3 and 52.29%, respectively. The highest amount of chlorophyll and carotenoid was obtained in melatonin treatment with 150 and 100 μM concentrations. The highest amount of phenol was recorded in plants treated with 100 µM melatonin under 60 mM salinity. The flavonoid content in 100 µM melatonin under 30 mM salinity was the maximum.

Effect of melatonin on enzyme activity and salinity tolerance of calendula (Calendula officinalis L.) based on the evaluation of morphophysiological characteristics Keywords:

Environmental stress , Catalase , Chlorophyll , Flowering , Ornamental Plant , تنش محیطی , کاتالاز , کلروفیل , گلدهی , گیاه زینتی