Jain, VeenaChawla, Sheetal2016-11-182016-11-182008http://krishikosh.egranth.ac.in/handle/1/86352Effect of salinity was studied on osmoregulation, enzymes and metabolites of reactive oxygen species (ROS) scavenging pathway in leaves and roots of Oryza sativa. For this, six cultivars of rice, three each salt-tolerant (Pokkali, CSR-1 and CSR-10) and salt-sensitive (Basmati-370, IR-28 and MI-48) were taken. The relative water content and osmotic potential decreased upon salinization in all the cultivars, however, the magnitude of reduction was more in salt-sensitive cultivars with increase in salt concentration. Na+/K+ also increased with increasing salt stress in all the cultivars, but the increase was much higher in the salt-sensitive cultivars than salt-tolerant cultivars. Similarly, the production of toxic reactive oxygen species (viz. .O2- and H2O2) and malondialdehyde content (MDA), which is an indicator of cell-membrane damage also increased in all the cultivars with higher level of increment in the salt-sensitive cultivars than salt-tolerant cultivars in both the tissues viz. leaves and roots. The salt-stress had differential effects on the antioxidant enzyme activities in leaves and roots of salt-sensitive and salt-tolerant cultivars. There was enhancement in the activities of superoxide dismutase and glutathione reductase in all the tolerant cultivars while the activities of these enzymes decreased with increasing salinity in the sensitive cultivars. Salt-stress induced the activities of catalase and peroxidase in all the cultivars but the magnitude of increase was more pronounced in sensitive cultivars than tolerant cultivars. Ascorbate peroxidase activity increased in both the tissues of the salt-sensitive cultivars and decreased in the salt-tolerant cultivars. However, the basal level was much higher in the tolerant cultivars. Contrarily, GPX activity declined in roots and leaves of sensitive cultivars but remained unaltered in salt-tolerant cultivars upon exposure to salt-stress. The tolerant cultivars had higher ratio of glutathione reduced (GSH)/glutathione oxidized (GSSG). Ascorbic acid content increased in leaves of tolerant cultivars while reduced in both leaves and roots of sensitive cultivars under saline condition.enStorage, Fruits, Sugar, Acidity, Reducing sugars, Productivity, Vitamins, Vegetables, Irrigation, BeveragesThesis