Effect of Indoleacetic Acid on Growth, Protein, Catalase and Peroxidase contents in Soybean plant (Glycine max (L.) Merr) under Aluminum chloride stress

In the present study، the effects of indole acetic acid (IAA) on certain physiological and biochemical parameters in Glycine max (L.) Merr under aluminum chloride (AlCl3) stress were studied. Seeds were sterilized and cultured in petri-dishes. Six days old seedlings were transferred to pots، and then they were irrigated with Hoagland solution in a growth chamber (with 16 h light period per 24 h، with day / night temperatures of 25/18 ºC respectively). Fourteen days old plants were treated with different concentrations of AlCl3 (0، 50، 100، 200 and 300 µM) and IAA (0، 50 and 100 µM). Plants were harvested 15 days after treatment. With increasing of aluminum concentration، NAR، RLGR، RWC، protein and soluble sugars contents decreased، however، SLA and peroxidase and catalase activities increased. With addition of IAA to culture solutions containing aluminum، the plants showed further decrease in the amount of soluble sugars، but the other parameters were adjusted. With increasing of aluminum concentration to culture solutions with and without IAA unsoluble sugars increased. Exogenous indoleacetic acid counteracted the deleteriots effects of Al3+ stress and helped plants to grow successfully under these adverse unfavorable conditions.