Screening of Soybean Genotypes at Seedling Stage under Salinity Stress

In order to understand the response of soybean genotypes to salinity stress, thirty soybean genotypes were evaluated in two separate experiments for normal (control, zero salinity) and salinity treatments (150 mM sodium chloride) in hydroponic culture medium containing hoagland nutrient solution with 3 replications at the greenhouse.The studied traits in this study were leaf area, shoot height, root length, fresh and dry weight of shoot and root, chlorophyll content (SPAD value), salt injury index, sodium and potassium in the shoot and root, the ratio of potassium to sodium of shoot and root, and the ratio of root to shoot Na and K ion translocation. Simple analysis of variance as well as combined analysis of lines and cultivars showed that the studied lines were significantly different from each other in terms of all studied traits at seedling stage, also, the interaction between genotype and environment was significant for most traits, indicating that the responses of cultivars and lines to salinity is different. Most of the studied traits showed a decrease compared to normal under stress conditions, except for salt injury index, sodium and potassium content in shoots, sodium content in roots, and the ratio of root to shoot Na and K ion translocation. Based on the results of statistical parameters among the studied genotypes, the highest coefficient of phenotypic diversity  were related to leaf area under stress (55.3), fresh root weight under stress (45.28), root dry weight under stress (42.26) and salt injury index under stress (37.99). The lowest coefficients of phenotypic diversity were related to root length under normal conditions (11.7) and chlorophyll content under normal conditions (13.3). The stability analysis of studied genotypes showed that cultivars such as Lee, SG13, Vernal, Will, Winchester, Douglas, LYON, Century 84, Strong, L.87-0174 and Crawford are among the lines that can be used as parents in hybrid blocks to improve salinity tolerance of new cultivars.