Salinity Induced Effects on Growth Parameters, Chemical and Biochemical Characteristics of Two Forage Sorghum (Sorghum bicolor L.) Cultivars

Plant production stability under saline condition compared to normal has had limited success due to lack of knowledge on salt tolerance mechanisms. To evaluate the changes in chemical and biochemical characteristics (content of free proline and total protein, Na+ and K+) and growth parameters (leaf area, plants height, total tiller number, leaf number, shoot and root weight, percent of emergence, growth rate and growth power) of sorghum under salinity stress, a pot experiment was carried out at Shiraz University, Shiraz, Iran in 2010. Four salinity levels containing 3, 6, 9, 12 ds m-1 using NaCL and without using NaCL (as control) and also two sorghum cultivars consist of Pegah (Iranian cultivar) and Speedfeed were evaluated in a factorial experiment design with three replications. Results showed that salinity decreased accumulation of K+, emergence percentage and all growth parameters but increased amount of Na+, proline and total protein content in shoot and leaves of treated plants. Multiple regression, stepwise selection, selected root weight and their ratio (shoot/root), leaf area and leaf number per plant, tiller number per plant, photosynthesis rate and also content of K+ as most significant factors for contributing in shoot weight. Stepwise selection and correlation coefficient cleared that root weight is the most important factor in plant shoot production under salinity condition and breeding program must be carried out to screen cultivars with higher root density in order to increase resistance to salinity. Based on the results, Speedfeed is proper cultivar to be used in breeding programs to achieve higher salinity resistance by screening or crossing programs.