Wu XiaoJin;Yuan LongPing;Wang WeiPing

;Hunan Hybrid Rice Research Center, Changsha, Hunan, 410125, China.

crop quality;crop yield;crosses;cultivars;disease resistance;elites;genes;genetic improvement;hybrids;lines;male sterility;plant diseases;plant pathogenic bacteria;plant pathogens;rice;specific combining ability;stigma

Using the gene derived from the recessive thermo-sensitive genic male sterile line (TGMS), a study was conducted to improve the stigma exsertion rate of the sterile rice lines and develop a new TGMS line by random polycross plus mass selection. N8S, Huaizao4, Xiang2B and Zaoyou1 cultivars were used as the parents to improve important characters such as combining ability, grain quality, resistance and stigma exsertion rate. Upon crossing N8S with Huaizao4, Xiang2B and Zaoyou1, respectively, population S1 was established by mass selection, population C1S1 by one-time random polycross and population C2S1 by two-time random polycross. Twenty sterile lines were selected from generations of S1, C1S1 and C2S1, and later test-crossed with Minghui63, Minghui77 and R402. Every hybrid was planted and compared with hybrids from crossing V20A (control) with the corresponding R lines. The stigma exsertion rate of ZhunS, the newly developed elite TGMS line was 78.6%, 72.4% higher than that of V20A. The hybrids produced by crossing ZhunS with R402, Minghui77 and Minghui63 increased the yield by 3.8-5.8% and decreased grain chalkiness by 82.1-84.4% compared with those from crossing V20A with the corresponding R lines. Bacterial leaf blight [Xanthomonas oryzae pv. oryzae] resistance was 3rd grade compared with the 8th grade of V20A. When ZhunS was combined with ~300 parental lines to develop elite hybrids, it showed a strong specific combining ability with R527 (restorer line)..