Journal of Taiwan Agricultural Research

Author:Charng-Pei Li, Yih-Chuan Kuo, Shu-Tu Wu and Fu-Sheng Thseng

Abstract:

Two sinica varieties, Tainung 67 (TNG 67) and Taiken 1 (TK 1), and a wild rice, O. nivara (Acc. 104705) were used as the recurrent parents and non-recurrent parent respectively to investigate the genetics and breeding behaviors including the days to heading, plant height and panicle length of the interspecific hybrid progenies. The F₁, F₂, BC₁F₁, BC₁F₂, BC₂F₁, BC₂F₂, BC₃F₁ and BC₃F₂ populations derived from the interspecific crosses along with their parents were planted simultaneously at the experimental farm of Taiwan Agricultural Research Institute in the first crop of 1996. The F₁ plants of two cross combinations exhibited the tendence of early-heading like their wild parent, O. nivara does. This showed O. nivara has some dominant early genes. The days to heading of F₂ population of TK 1 × O. nivara had two peaks. This suggested the early gene of O. nivara differs from the gene of TK1, which was also classfied as an early mature cultivar. O. nivara belonged to a semidwarf of about 100 cm. The plant height of F₁ derived from TNG 67 × O. nivara combination was tended to exhibit complete dominance like TNG 67 and panicle length was tended to exhibit as partial dominance like O. nivara. Heterosis was found on both characters in the TNG 67 × O. nivara combination. A large variance and transgressive segregation were observed in F₂ populations for both cross combinations. Although many weak plants with shorter plant height and panicle were found in the BC₂F₂ populations for both cross combinations, less variances were also observed in backcross populations When cross generation increased. Positive phenotypic correlactions were found among the days to heading, plant height and panicle length in F₂ populations in both cross combinations. Positive correlations were found between plant height and panicle length in each backcross F₂ populations of both cross combinations. However, negative correlations were observed between the days to heading and plant height in all the backcross F₂ population of back cross in both cross combinations, except the BC₃F₂ of TK 1 × O. nivara.

Key words:Oryza sativa, O. nivara, Interspecific hybridization, Recurrent backcross. Agronomic characters

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