Salinity effects on osmotic potential, soluble proteins and carbohydrates concentration in rice (Oryza sativa) genotypes at seedling stage

Rice (Oryza sativa), a salt-sensitive species, has considerable genetic variation for salt tolerance within the cultivated gene pool. To evaluate salinity effects on osmoprotectants accumulation two rice genotypes (IR29 and IR651, sensitive and tolerant respectively) accompany with two semi-tolerant Iranian rice cultivars, an experiment were carried out on the Agricultural BiotechnologyResearch Institute of Iran in the growing season of 2006-2007 in a green house. The experiment were grown in normal condition till 6th leaf was fully expanded. Seedlings were exposed to salinity, EC 12 dS m 1 and normal conditions (EC = 1.65 dS m-1, Ushida solution base EC) for one week. Samples were taken 0, 4, 12, 24, 48, 96 and 168 h after starting the treatments. The amount of soluble organics were measured with spectrophotometer after extraction. The concentration of soluble carbohydrates in tolerant cultivars (IR651) increased significantly compared to other cultivars under saline condition. The variation of soluble proteins were not significant in all cultivars in stress treatment, but at the end of experiment protein concentration accumulated in tolerant cultivar whereas decreased in others. So the decrease of osmotic potential till to -1.43 MPa in tolerant cultivar was related to the high ability of this cultivar to synthesis of organic matter like soluble carbohydrates to prevent of dehydration.