Effect of Salinity Stress on Growth, Yield and Some Physiological Traits of Forage Sorghum Cultivars

In order to evaluate the effect of salinity stress on growth, yield, and some physiological traits of forage sorghum cultivars, an experiment was conducted as split-plot based on a randomized complete block design with four replications at experimental farm of College of Agriculture, Shiraz University at 2014 growing season. Treatments were three levels of saline irrigation water (0.4 as control, 7 and 14 dS/m) and three sorghum cultivars (Pegah, White speedfeed and Red speedfeed) as main plots and subplots, respectively. Results showed that salinity stress decreased plant height and leaf area. Pegah cultivar showed the highest forage dry weight in all salinity treatments. Activity of antioxidant enzymes including superoxide dismutase, peroxidase and catalase significantly increased with increasing salinity levels in Pegah and Red speedfeed cultivars. In salt-stressed Pegah these enzymes activity increased 2.1, 4.5, and 2.8 times, respectively in comparison to control. With increasing salinity levels, shoot sodium/potassium ratio of White speedfeed, Red speedfeed, and Pegah cultivars increased  10.7, 6.8, and 1.7 times, respectively whereas root sodium/potassium ratio of the cultivars increased 9.6, 8.1, and 4.7 times, respectively. It seems that the lower absorption of sodium was the major mechanism of salinity tolerance in Pegah and can be an important criterion to evaluate sorghum salinity toleranc