Physiological and growth responses of Calendula officinalis L. plants to the interaction effects of polyamines and salt stress

Salt and water stresses are the most important factors limiting plant growth and productivity in the world. Polyamines are shown to have a role in adaptation of plants to salt stress condition. Effects of exogenous spermine (Spm) and spermidine (Spd) on growth and physiological traits were investigated in Calendula officinalis L. plants under salt stress condition. At all levels of salt stress application of Spd at 1 mmol concentration affected significantly shoot dry matter, peroxidase activity (POD) and proline, protein and total chlorophyll contents compared to the other levels of polyamines. Oxidative activities of malondialdehyde (MDA) and hydrogen peroxide (H2O2) were decreased when plants were treated by 1mM Spm concentration under salt stress conditions. Whatever was the salt stress level, application of Spm at 1mmol increased catalase activity (CAT) and maximum photochemical quantum yield (F-V/F-M) of calendula plants. Results of this study suggest that poly amines may increase plant tolerance to salt stress by decreasing oxidative damages and increasing enzyme activities.