Variability in response to salinity stress in natural Tunisian populations of Hordeum marinum subsp. marinum.

Soil salinity is one of the most serious environmental factors affecting crop productivity around the world. In this study, we analysed morpho-physiological variation in responses to salt stress in Tunisian populations of Hordeum marinum subsp. marinum. The plants were grown under two treatments (0 and 200 mm NaCl) until maturity. A total of 19 quantitative traits were measured before and during the harvest. It was observed that most studied traits are influenced by the increasing salinity. High to moderate broad-sense heritability (H2 ) were noted for most of parameters under control and salt treatment, implying that salt tolerance is moderately heritable and environmental variation plays an equally important role. The majority of correlations between measured traits under the two treatments are positive, where the strongest correlations were between spike number (SN) and weight (SW). Based on the salt response index (SRI) values, SN and SW are the most affected by salinity. The 150 studied lines formed three groups according to the SRI values of the 19 quantitative parameters, of which 101 were moderately sensitive, 27 tolerant and 22 highly tolerant. Overall genetic variation of H. marinum in response to salt stress may provide novel insight to identify genes responsible for salt tolerance.