Studies On Combining Ability For Agronomic And Quality Characters Of BT Type CMS Lines And Iso-cytoplasmic Restorers Newly Bred In Japonica Rice (Oryza Sativa L.)

The combining ability of the CMS lines and Iso-cytoplasmic restorer lines in the main agronomic and quality characters were studied by using the combinations made from CMS lines with BT type cytoplasm and Iso-cytoplasmic restorers and in-cytoplasmic restorers in Japonica rice with twice NC II genetic design. The CMS lines and Iso-cytoplasmic restorers were newly bred by the strategy "transferring by back cross, crossing between different ecological type" .The results were the fellows:(a) The combining ability of CMS lines in 7 agronomic traits and 10 quality characters were studied by using the 30 combinations made from the 6 CMS lines newly bred with BT type cytoplasm and 5 restorers with NC II genetic design. The results were as follows: (1) For agronomic traits, 3004A, SidaolOA and 4108A were elite CMS lines, while 9311 and C418 were elite restorers in terms of GCA. For quality characters, CMS lines 4002A, SidaolOA, 4016A, Wuyujing3A and the restorers Xiangqing, C418, HP122 had good GCA. Considering both agronomic and quality characters, 3004A, Sidao10A and 4002A were the ideal CMS lines, while Xiangqing, C418 and HP 122 were the superior restorers. (2) 4002A/NanR187, 4016A/NanR187, 3004A/Xiangqing, 4108A/Xiangqing, 4002A/9311, 4108A/9311, 4016A/C418, 3004A/HP122, Sidao10A/HP122 and 4016A/HP122 were excellent combinations. (3) Except gelatinizaton temperature and amylose content , the variance of GCA in other 15 characters were larger than that of SCA. The GCA variance of restorers was larger than that of CMS lines in all characters except panicle length, total spikelets per panicle,rate of chalkiness and gel consistency.(b) The hybrids' performance and the Iso-cytoplasmic restorers' combining ability of 8 agronomic traits and 10 quality characters were studied by using the 36 combinations made from 4 CMS lines with BT type cytoplasm and 5 Iso-cytoplasmic restorers newly bred and 4 In-cytoplasmic restorers with NC II genetic design. The results were as follows: (1) The high parent heterosis of 8 agronomic traits were from 5.56% to 58.33%, that of heading date was the lowest, while that of yield per plant was the highest. The mid-parent heterosisof 8 agronomic traits were from 27.78% to 77.78%, that of heading date was the 27.78%, that of other traits were bigger than 55.00%. The competitive heterosis of 8 agronomic traits were from 8.33% to 58.33%, that of panicle length were the lowest and yield per plant was the highest. (2) Except the high parent hererosis of heading date, panicle length, 1000-grains weight and the mid-parent heterosis of 1000-grains weight, the high parent heterosis and mid-parent heterosis of Iso-cytoplasmic restorers were lower than that of In-cytoplasmic restorers in other agronomic traits. The competitive hererosis of Iso-cytoplasmic restorers were lower than that of In-cytoplasmic restorers in other 6 agronomic traits except 1000-grains weight and panicles per plant, but the deviation in yield per plant was not significant. (3) For the average of quality characters, refer to the In-cytopolasmic restorers, the Iso-cytoplasmic restorers increase the hybrids' brown rice percentage 1.07%, milled rice percentage 0.83%, head rice percentage 0.74% and decrease chalkiness score 0.46%, rate of chalkiness 0.54%; The hybrids made from Iso-cytoplasmic restorers increase gelatinization temperature (represented by alkali spreading value) 0.06 grade and amylose content 0.68%, decrease gel consistency 0.08cm. (4) For agronomic traits, 4016A and Zhendao88A were elite CMS lines, while C418, Xiangqing and LiuqianxinR were elite restorers in terms of GCA. For quality characters, CMS lines 4016A. QingkongA and the restorers 6427R, Wuyujing3R, Liuyanl89R had good GCA. Considering both agronomic and quality characters, 4016A and Zhendao88A were the ideal CMS lines, while 6427R, Liuyanl89R and Xiangqing were the superior resters. (5) For agronomic traits, 4016A/77302-1, YueguangA/C418 and Zhendao88A/C418 were excellent combinations; For quality characters, 4016A/3726R, 4016A/LiuqianxinR and QingkongA/H...