STUDIES ON COMBINING ABILITY AND HETEROSIS FOR SOME TRAITS OF ROOT AND YIELD CHARACTERS OF SOME RICE GENOTYPES UNDER NORMAL AND WATER DEFICIT CONDITIONS

Eight genotypes cultivars of rice were crossed to obtain 15 F 1 crosses, through line x tester mating design was employed for this purpose. The experiment was carried out using line x tester mating design, during 2021 and 2022 rice growing seasons at the experimental farm of Sakha Research Station, Sakha, Kafr El-Sheikh, Egypt. Both GCA and SCA variances were found to be significant or highly significant for all studied traits. The estimates of GCA effects indicated that, the parent IR 12 G 3222 was a good general combiner for root length, number of roots/plant, and flag leaf area under both conditions. In addition, GZ 1368 was a good combiner for root volume under both conditions. While the line IR 69432 was a good combiner for root/shoot ratio under water deficit condition. The line 11 L 236 for chlorophyll content, number of filled grains/panicle, grain yield/plant and the tester Giza 178 for relative water content and grain yield/plant were good combiners under both conditions. On the other hand, the cross combinations, IR 69432 X GZ 1368 was found to be the best specific combinations for root length, number of roots/plant, root volume and root/shoot ratio under two conditions. The cross combination, IR 12 G 3213 X Giza 178 was the best specific combinations for relative water content, flag leaf area and chlorophyll content under both conditions . The cross combination, IR 12 G 3222 X Giza 178 was the best specific combination for 1000-grain weight and fertility % under both conditions. In addition, the cross combination, IR 69432 X GZ 1368 under normal and IR 69432 X