Evaluation and utilization of the offsprings derived from indica-japonica cross.

The method of continuously polymerizing and accumulating different favorable genes was used.The breeding practice of heterosis utilization between indica and japonica lasted for 21 years and went through 4-selected phases.32 derived lines of the hybrid breeding indica-japonica rice were bred.The effect and effective utilization of the derived lines in improving indica-japonica hybrid rice were evaluated.The breeding process and the analysis of the yield-related traits of the derived lines show that: the breeding of the derived lines is a process of gradual recognization and improvement.First,at the early stage of breeding,many wide compability genes and restoring genes should be polymerized and special attention should be paid to the tillering ability,the 1000-grain weight and the shattering trait.At the middle stage,the problems in practical production should be solved and the agronomic traits and the grain plumpness should be improved.In the practical stage,the goal of the application and popularization of the derived lines can be achieved.Second,the selection of the offsprings of restorer line in hybrid breeding indica-japonica rice differs from the conventional selection.The best way to select the offsprings of restorer line is that restorer line should be crossed with many different cytoplasmic sterile lines.Third,in order to enhance the heterosis,enlarge the genetic difference of inter-subspecific parents and moderately enhance japonica composition while improving the comprehensive characters of restorer line.Fourth,continuously polymerizing and accumulating favorable genes and combination of good plant-type,high yield,good quality,stress-resistance and adaptability is the breeding strategy and technique to select practical,strong superior indica-japonica hybrid rice.