Role of Melatonin in Water Stressed Soybean Plants.

Melatonin’s role in circadian processes in human and various animals is well known. Recenlty melatonin has been found in different parts of a plant and have been reported by some authors to effect the expression of other plant hormones, hence, it is suggested to have role in various physiology important in germination, cell growth, senescence, and flowering in plants. Other studies have reported an upregulation of melatonin in plants in response to biotic and abiotic stress, strongly suggesting a role in stress physiology. It is considered as a powerful antioxidant that plays a role in the defense system. In the present study we investigate the role of endogenously applied melatonin to 10 day old germinating soybean seeds under successive water stressed conditions. The study was conducted in the greenhouse conditions in 2 sets of three groups. The control group with 2, 3, and 9 days irrigation interval. The second set consisting of the treatment group with the same irrigation regimen. Melatonin was added at the rate of 0.03/ml in the soil to 10 day old emerging seedlings. The preliminary results have shown overall healthier growth with melatonin treated plants in terms of plant height, and leaf size under 3 and 9 days irrigated pots, compared to pots. Chlorophyll content and stomatal conductance measured higher at the end of three weeks in treatment groups (chl;27.8)(St.con;1363) compared to control (chl;18.59)(St.con;359) in 9 days water stressed plants. Our present study with melatonin application showed positive responses in physiology and protection of plants in water stressed conditions.