Effect of melatonin on some of the physiological and biochemical parameters of Tobacco (Nicotiana tabacum L.) under drought and salt stresses

Abstract

Plants are generally exposed to abiotic stress factors such as drought and salt. Objective of this study was to compare the changes that salinity and drought stress would create simultaneously and individually on tobacco plant and to determine the changes by melatonin application. A pot experiment was conducted in a growth chamber and replicated three times in 2016. For this reason, half of the plants were subjected to 50 mu M melatonin, the other half was left untreated. Prior to the melatonin application, NaCl (50 mM) and PEG (10%) stress effects were applied both individually and combined (50 mM NaCl + 10% PEG). The results indicated that chlorophyll content in tobacco plants was decreased, however the carotenoid contents, proline, malondialdehyde and activities of ascorbat peroxidase and guaiacol peroxidase were increased. Mentioned activity changes were even greater for the combined stress factor application. On the other hand, in 50 mu M melatonin applied plants were found to be increasing in enzymatic activity as well as the contents of pigment, prolin and malondialdehite. This study illustrated that melatonin application on the leaves coordinates the stress response and decreases the negative effect of the drought and salinity.