Jain, VeenaDalal, Sudha2016-09-152016-09-152014http://krishikosh.egranth.ac.in/handle/1/76784Four indica/Basmati and aerobic rice varieties (HBC19, HKR47, MAS25 and MAS26) were used to study various morpho-physiological, biochemical parameters under water limiting conditions. For this the plants were grown in pots and were subjected to flooded as well as aerobic water conditions and in another experiment PEG induced water stress of -1 and -2 bar was generated in hydroponic conditions. Aerobic rice genotypes performed better than indica/Basmati rice varieties under aerobic as well as water stressed conditions in all aspects of physio-morphological and biochemical attributes. Large deviation was observed in all rice genotypes for shoot length, root length, dry shoot weight and dry root weight in six weeks old seedlings when grown under aerobic conditions and in hydroponic system (at -1 and -2 bar). Relative water content (RWC) and osmotic potential reduced significantly under water limiting conditions in all the varieties. The production of toxic reactive oxygen species (ROS) (viz. .O2 - and H2O2) and lipid peroxidation (MDA), which is an indicator of cell membrane damage also increased in all the cultivars with higher level of increment in the conventional cultivars than aerobic rice varieties. The total level of ascorbic acid glutathione and proline was higher in aerobic rice varieties under water limiting conditions in both the experiments. Water stress had differential effect on antioxidant enzyme activities in shoots and roots of conventional and aerobic cultivars. Under hydroponic system, SOD activity increased in all the cultivars however, the increase was higher in aerobic rice varieties. Though it declined in all the cultivars under aerobic conditions in pot experiment, yet the total activity in aerobic genotypes under water limiting conditions was higher than that of conventional varieties under control conditions. CAT activity decreased in shoots of all rice cultivars however, in roots the CAT activity remained unchanged and increased in conventional rice varieties and decreased in aerobic rice varieties grown under aerobic conditions. Under hydroponic conditions CAT activity enhanced at -1 bar but declined at -2 bar level of stress in both shoots and roots. Water stress resulted in increased activity of POX and APX in both tissues of all the cultivars in both the experiments but absolute were significantly more in MAS25 and MAS26. Water stress decrease GR activity in shoots but GR activity increase in roots in all the varieties yet the total values were higher in aerobic rice varieties.enRice, Irrigation, Planting, Enzymes, Vegetative propagation, Weather hazards, Tolerance, Antioxidants, Biological phenomena, HydroponicsThesis