Study of Genetic Diversity Tolerance to Salinity Stress in Alfalfa (Medicago sativa L.) Varieties Basis on Seedling Growth

In order to study of variation and the effect of 5 salinity level (0, 75, 150, 225 and 300 mmol) of NaCl on 20 alfalfa genotypes, a factorial experiment was conducted based on CRD with three replications in green house condition of Shoushtar Islamic Azad University, Iran in 2011. Seeds were sown in pots containing 1:2 sand-agriculture soils and irrigated by tap water for 45 day. Then the pots were irrigated by salt water for 14 days. Seedling characteristics as number of leaf per plant, root length, stem length, seedling length, seedling root shoot length ratios, seedling fresh and dry weight and dry fresh weight ratios were measured. The results of analysis of variance showed significant effects of genotypes, stress and genotype by stress interaction effects for all of traits (P<0.01). By increasing salinity all traits were decreased except root shoot length ratios. The results indicated that the critical salt dose for shoot and root caracterstics were 150 and 300 mmol, respectively. Using cluster analyzes, the genotypes were split into three groups. KFA1, KFA11, KFA14 and KFA15 originated fro GarehYounjeh, KFA4, KFA6 and KFA16, originated from Hamedani and cultivar Bami Garmsiri were considered as the most tolerant groups and KFA3, originated GarehYonjeh, KFA5 and KFA17, originated Hamedani, KFA7 originated Rahnani, cultivars Nikshahri Garmsiri and Yazdi Garmsiri were considered as the most sensitive groups and the other ones as semi-tolerant to salinity stress.