Characterization And Combining Ability Of New CMS Lines Improved Using Zhenshan 97 B, An Early Maturity Maintainer, In Indica Rice (Oryza Sativa L.)

Zhenshan 97B is an early maturity cultivar, which was bred in the cross of Zhenzhuai×Xianaixuan 4 by Institute of Wenzhou Agricultural Sciences in 1968, in indica rice (Oryza sativa L). In 1970, male sterile line Zhenshan 97A with WA-type cytoplasm was successfully bred by backcrosing method. The breeding of Zhenshan 97 A with WA-type cytoplasm was an important breakthrough in the history of hybrid rice application research in China. Zhenshan 97A had several merits, such as good combining ability, adoptive widely, resistant to blast disease. However, Zhenshan 97A had also several shortcomings, such as poor quality, susceptible to black blight disease and striple blight diseae, and low yield of seed production. In order to maintain the merits and overcome the shortcomings, we have bred 6 new cytoplasmic male (CMS) sterile lines by crossing Zhenshan 97 with other cultivars in recent years in Wenzhou Academy of Agricultural Sciences. In this study, four experiments were carried out to evaluate the value of these CMS lines newly bred for seed production in early maturity indica rice. Firstly, the characterizations of the CMS lines were evaluated. Secondly, outcross rates and F1 seed production yields were compared between the new CMS lines and the chech CMS line, Zhenshan 97A. Thirdly, combining ability of 7 important agronomic traits was studied by using 49 F1 combinations made from the 7 CMS lines and 7 restorer lines. Forthly, ten quality traits of the 49 F1 and their 14 parents were measured and analysed. The main results obtained were as follows.1. Outcross rates were improved in New CMS lines compared with Zhenshan 97A. Outcross rates of Zhenpin A, Zhennong 256A and Zhennong 257A were 81.6%,89.5% and 88.1%, respectively, while that of Zhenshan 97A was 47.5%. Zhenpin A was highly resistant to rice seedling blast and panicle blast, showing zero grade of disease rate. Grain length of new CMS lines was longer than that of Zhenshan 97A. Apices colour of spikelet in Zhennong 257A was changed to green colour, the others remain purple colour. The improvements of stigma exsertion rate, grain shape and resistance to blast disease in new CMS lines will benefit F1 seed production.2. F1 seed yields of Zhennong 257A/48-2, Zhennong 256A/48-2, Zhenpin A/48-2 and Zhennong 567A/48-2 were 3127.1 kg,3073.8 kg,3058.5 kg and 2966.7 kg per hactare respectively, increasing 14.3%,12.4%,11.8% and 8.5% respectively compared with that of Zhenshan 97A/48-2 combination. The seed production yields is high, for the high stigma exsertion and outcross rates of New CMS lines, So the problem of low seed production yields of Zhenshan 97A can be perfectly solvable. It can effectively reduce the cost of production, which is beneficial to the utilization and extension of hybrid rice.3. The high-parent, mid-parent and low-parent values of 49 F1 combinations and seven Agronomic Characters are all positive, especially in the better-parent value of the grain weight per plant (GWP). Zhenpin A was the best CMS line in terms of general combining ability for yield, spikeleta per panicle and filled grains per panicle. Zhenpin A/R402, Zhenpin A/Wenhui 359, Zhennong 567A/Wenhui 359, Zhennong 256A/Wenhui 266, Zhennong 257A/Wenhui 226, and Zhennong 257A/R402 were elite combinations.4. According to the standard of NY/T-593-2002 made by Agricultural Department of China, Zhenpin A/R402, Zhenpin A/Wenhui 266 and Zhenpin A/Wenhui 619 reached standard of third grade, which belongs to super quality rice varities for eating. According to the test synthesis results of rice quality, the combination of New CMS lines can effectly improve the poor quality of Zhanshan 97A.