study some physiological and morphological responses of three sugar beet cultivars to salinity stress

to study some physiological and morphological traits of sugar beet varieties in response to salinity stress, three multi-germ sugar beets (13030, 22393 and ic) were grown in the greenhouse, faculty of agriculture, shahid chamran university, in 2009. the experiment was carried out under three levels of salinity in from of sodium chloride source, that included control (zero), 100 and 200 mm uses factorial design test based on a randomized complete block with three replications. seeds were sown in plastic pots and salt treatments were begun 30 days after sowing. after 60 days salt treatment, the plants were harvested and analyzed. the analysis of variance results showed that salinity had significant effect on all of the parameters. the results of mean comparisons showed that by increasing salinity, root dry weight, shoot and leaf area significantly decreased, but salinity had not significant effect on the leaf number. indeed, by increasing of salinity, the relative water content of leaf and stomatal conductance were decreased, while, the relative membrane permeability and proline content in leaves of all genotypes increased. higher concentrations of sodium chloride decreased osmotic potential. an increase of proline neither affected electrolyte leakage nor plant water status. therefore, in sugar beet, the antioxidant role of proline could not provide plasma membranes protection against damage caused by salt stress. according to this study, root dry weight of 90 days plants, sis was related to drought tolerance in the three varieties studied.