Sesamum indicum L. (family-Pedaliaceae) is an economically important oil seed crop grown in tropical and sub-tropical countries. It is widely used in food, nutraceutical, pharmaceutical industries. Salinity is considered as the most important abiotic stress limiting to crop production. In this context, the present study was to evaluate the Sesamum genotypes for salinity tolerance. Germinated seedlings (15-d-old) were used to screen the germplsm at different concentrations (0, 25mM, 50mM, 75mM, 100mM) of NaCl and observation was taken after 15th, 30th and 45th days of treatment. Ion content (Na+, Cl-, Ca++, Mg++ and K++ ) were measured after 15 days of treatment. Fresh and dry weight was less in salt sensitive genotypes than tolerant genotypes. During increase of salinity concentration, all the genotypes had a negative impact on roots. The seedlings showed reduced growth and displayed variation in ion uptake thus accumulating Na+ and Cl- in the roots. At higher concentration of salt treatment showed the more dry weight and displayed more effective ion regulation by manipulating low Na+/K+ and Na+/Ca++ ratio. The tolerant genotypes exhibited the lowest shoot Na+ content under salinity conditions. Higher proline accumulation was observed at 100 mM after 15 days of NaCl treatments in KM-13 genotype. After 15 days of treatment, the genotype ES 2138-2 showed maximum proline accumulation. The total carbohydrates contents increased in all the ten genotypes in presence of NaCl. Highest carbohydrate content was found in genotype SI-1926 grown in 100 mM NaCl. Enzyme activities are variable in different genotypes with different concentration of NaCl. This study will help in Sesamum improvement programme.
Key words: Sesamum genotype, Protein, Proline, Salinity stress, Oxidative enzymes
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