Biological Characteristics And Combining Ability Analysis Of Wen-Xuan Restorer Lines In Rice (Oryza Sativa L.)

Rice is one of the most important food crops in the world, more than half of the world’s populations choose rice as the staple food, and rice is also the main cultivated crop in China. In recent years, the parents for hybrid rice breeding had a closer genetic relationship and narrow genetic difference, positive advantage of hybrid variety was getting smaller. It was more and more difficult to have a breakthrough to improve rice yields through heterosis. In this study two researches were done. One was the evaluation of biological characteristics of two Wen-xuan restorer lines, Wenhui 365 and Wenhui 845, which was bred by crossing Reiyan 1 and Wenhui 233, and by crossing Peiai 64 and Suweon 297, respectively. The other was the combining ability ananlysis of 5 restorers and 7 CMS lines through NCII genetic design. The main results were as follows.1. In Wenhui 365, the plant height was 107 cm, productive panicles per plant was 10.3, panicle length was 26.3cm, spikelet per panicle was 133.2, filled grain per panicle was 124.0, seed set 93.0%,1000-grain weight 25.9g. Four indicators of milled rice reached first class grade of national standard and 2 indicators reached second class grade of national standard. Seed set of F1 plant reached 83.5% and 88.9%, respectively when crossed with japonica rice Banila and CMS Ninghui 67A. The plants of Xinlu A/Wenhui 365 was insensitivity to light length. The growth duration of Wenhui 845 was 83 days to heading. The plant height was 98cm, productive panicles per plant was 14.2, panicle length was 23cm, spikelet per panicle was 98, filled grain per panicle was 87.6, seed set 90.0%, 1000-grain weight 26g. Ⅱ you 845 and Yi you 845 were high resistant to rice brown hopper with a duration of 38 days.2. Combining ability analysis for seven traits yield-related was conducted using 35 combinations made from seven CMS lines and five indica restorer lines following the genetic mating design of North Carollina Ⅱ. It was found that Wen-hui 365 was an ideal restorer line for making heterotic bybrid among the 5 restorers, and that R117 and Wen-hui 485 were also valuable restorer materials. Xin-lu A/R845 was the combination showing the highest grain yield per plant among the 35 combinations investigated. The genetic variation of grain yield per plant, spikelet per panicle, filled grain per panicle,1000-grain wei,ght, panicle length and plant height in the F1 population was mainly caused by additive effects, while that of productive panicle per plant was caused by non additive effect. The narrow heritabilities of plant height and 1000-grain weight were high (80%). The narrow heritabilities of panicle length, spikelet per panicle and filled grains per panicle were medium (50%). And the narrow heritabilities of productive panicle per plant and grain yield per plant were low (8%).