Evaluation of Growth and Physiological Responses of Sorghum Varieties to Irrigation Water Salinity

In this study, salinity tolerance of five sorghum varieties (Speedfeed, Kimia, Payam, Sepideh, and Pegah) was studied using five irrigation water salinity levels (non-saline water, 4, 8, 12 and 16 dS/m) in the greenhouse. The statistical design was a factorial randomized complete block design with 25 treatments and four replications. The studied traits included plant height, leaf area, dry weight of roots and shoots, ratio of dry weight of roots to shoots, leaf chlorophyll index, concentration of sodium, chlorine and potassium in leaves and roots. The effect of variety and the effect of salinity stress on the mean of all measured traits were significant (P <0.01). At salinities of 4, 8, 12, and 16 dS/m, shoot dry weight was lower than the control (5.72 g/plant) by16.2%, 35.1%, 55.7%, and 69.4%, weight of dried roots lost 26.6%, 53%, 72% and 82%, compared to the control (5 g/plant), and the leaf area of the plants decreased by 29.4%, 58.3%, 75.5%, and 86.3% compared to the control, respectively. There was a negative correlation between chlorine and leaf sodium concentrations with shoot dry weight. Fisher stress sensitivity coefficient was used to evaluate the salinity sensitivity of cultivars based on shoot dry weight. Based on this coefficient, Speedfeed variety had the lowest salinity sensitivity coefficient (0.73) and Pegah cultivar had the highest (1.21). Regression was determined between different salinity levels with shoot dry weight for each cultivar. Accordingly, Speedfed, Kimia, Payam, Sepideh, and Pegah cultivars suffered a 50% reduction in shoot dry weight in salinities of 13.89, 12.95, 9.73, 9.62 and 9.50 dS/m. Based on the results, Speedfeed variety had a higher salinity tolerance than other cultivars and is recommended for cultivation in saline soil and water conditions.