Improvement of some physiological responses of alfalfa (Medicago sativa L.) under in vitro salt stress using Triadimefon

This study was carried out to investigation the possibility of using Triadimefon (TRD) in order to decrease the adverse effects of salt stress on Medicago plant. Triadimefon is a member of Triazol compounds which enhances stress tolerance through physiological processes. Two cultivars of Medicago sitiva including Hamedani and Yazdi were used in this study. Plants were treated with 1, 2 and 4 mg/l TRD and 0, 100 and 140 mM NaCl. Salinity reduced fresh and dry weight of plants in both cultivars with the result of higher reduction in cv. Hamedani significantly. Salt stress also increased proline, MDA and H2O2 contents and also the activity of SOD and P5CS, and the level of P5CS ranscripts, while decreased the activity of CAT and POX in both cultivars. When plants were treated with TRD and NaCl, less proline, MDA and H2O2 accumulation occurred. Interaction of NaCl and TRD increased SOD but reduced P5CS and CAT activity. Both NaCl and TRD treatments increased P5CS transcription in cultivar Yazdi while showed less effect in Hamadani cultivar. Interaction of TRD and NaCl alleviated the negative effects of salt stress on plant growth, especially at 2 mg/l TRD. The results of the present study showed that 2 mg/l TRD was the most effective level to alleviate the negative effects of NaCl treatment on Medicago sativa plants.