雄性不稔性을 利用한 水稻 雜種品種 開發 Ⅸ. 細胞質的 雄性不稔系統 育成過程中 戻交雜 回數에 따른 組合能力의 變異

Development of hybrid rice facilitated by cytoplasmic-genetic male sterility Ⅸ. Variability of combining ability of CGMS lines in different backcross generations

The objective of this experiment was to pursue the variability of combining ability for CGMS lines in different backcross generations. Sixteen CGMS lines from F₁, to BC₃F₁ were bred through backcrosses to the two recurrent parents known as maintainer of waxy Tongil-type, wx126 and wx817, utilizing two cytoplasmic male sterility of the WA source such as V20A and Z97A CGMS lines. Those newly developed CGMS’ were crossed with 7 Korean cultivars known as restorer of Tongil-type and through the backcross generations, the combining ability of grain yield and the variations of the yield associated characters were examined. The yield performance of fertile hybrids from different backcross generations were in order of F₁ CGMS×restorer＞BC₃F₁ CGMS×restorer＞BC₂F₁ CGMS×restorer＞BC₁F₁ CGMS×restorer. Regardless of the number of backcrosses, the variation of combining ability was the greatest for grains per panicle and percentage of filled grains with the similar tendency of grain yield from different backcross generations. The yield performance of the hybrids tend to be greater in the crosses of the CGMS lines originated from V20A than those from Z97A.