Effect of Salinity on Different Growth Stages of Wheat, cv. Roshan

To determine salinity tolerance of wheat (Triticum aestivum L.) at various growth stages، a controlled experiment (lysimeter conditions) was conducted at the National Salinity Research Center. Experimental design consisted of six treatments replicated three times in a randomized complete block design. Treatments were application of salinity at establishment stage، tillering، stem elongation، spike emergence، during grain filling period till final growing season and without imposing salinity (control). Wheat plants were grown in eighteen boxes (0. 5×0. 4 m and 0. 5 m depth) contained washed sand. Plants were irrigated 2-4 times daily using nutrient solution. The results showed that from emergence to tillering and from emergence to stem elongation phases were two sensitive stages of wheat growth to salinity stress and spike length and plant height were reduced significantly. Biological yield was considerably reduced by imposing salinity at establishment stage through growing season. Delay in application of salinity was associated with lower reduction in biological yield. Salinity reduced grain yield more severely when salinity stress was imposed at earlier stage of growth. Based on the results reduction in biological yield and the number of plants per unit area were the main contributing factors in grain yield reduction under salinity stress conditions.