Parental analysis of soybean cultivars released in china

Chinese. 【目的】研究中国1923～2005年育成大豆品种的系谱,分析其祖先亲本和直接亲本的来源和类型,归纳出近20年来最重要的祖先亲本和直接亲本,为今后大豆育种亲本选配提供参考。【方法】利用1923～2005年全国6个生态区育成的1300个大豆育成品种的系谱资料研究其祖先亲本和直接亲本组成,计算其核遗传贡献值。【结果】1923～2005年1300个大豆育成品种来源于670个终端祖先亲本,其中51.64%为地方品种、38.36%育种品系、7.01%改良品种、2.54%野生豆和0.45%类型不详,相应核遗传贡献率分别为76.29%、14.93%、7.79%、0.54%和0.45%。1391个直接亲本由育成品种、外国品种、地方品种和育种品系4类型组成,分别占27.76%、6.10%、11.62%和54.52%。在全国1019个杂交育成品种中,以育成品种和育种品系作为直接亲本的组配方式比例最高,达71.78%。归纳出了1986～2005年间中国941个大豆育成品种最重要的54个祖先亲本和37个直接亲本。【结论】与1923～1995的相比,近十年来中国大豆育成品种遗传基础有所拓宽,祖先亲本和直接亲本群体扩大了近一倍,地理来源更广泛。但遗传贡献有向少数祖先亲本集中的趋势，各生态区间的种质交流仍少。中国大豆品种遗传基础有待进一步拓宽.

English. [Objective] The present study was aimed to analyze the pedigrees of the 1 300 cultivars released during 1923-2005, to reveal the geographical sources and types of their end ancestors and direct parents, especially those during the recent 20 years, and to summarize the implications in utilization of breeding approaches and parental materials. [Method] Based on the collected pedigree data of the 1 300 soybean cultivars released during 1923-2005 in China, the end ancestors and direct parents were traced and then the nuclear contribution from the ancestors estimated and analyzed. [Result] Total 1 300 released soybean cultivars were traced to their 670 final ancestors, composed of 51.64% landraces, 38.36% breeding lines, 7.01% improved cultivars, 2.54% wild accessions and 0.45% uncertain type, which provided 76.29%, 14.93%, 7.79%, 0.54% and 0.45% nuclear contribution to the 1 300 released cultivars, respectively. The 1 300 released cultivars were derived from 1391 direct parents, composed of 27.76% cttltivars, 6.10% exotic introductions, 11.62% landraces, and 54.52% breeding lines. Among the 1 019 released cultivars developed from artificial hybridization, about 71.78% were from the crosses among cultivars and breeding lines. Total 54 major ancestors out of the 670 ones and 37 major direct parents out of the 1 391 ones of the cultivars released during 1986-2005 were nominated. [Conclusion] After a comparison between the data of the cultivars released during 1923-2005 and those during 1923-1995 reported before, the number of end ancestors and direct parents was about the double, the exotic germplasm increased, the geographic source extended, and therefore, the genetic bases of cultivars released during recent ten years in China were broadened. However, the most part of the end ancestors was used in only 1-5 released cultivars, while only a few end ancestors provided large genetic contribution but still limited basically in their local ancestors. The authors emphasized the utilization of germplasm rather than the local sources for broadening the genetic base of future cultivars, and suggested further exploration of the genetic structure and potential of core ancestors for achieving breeding by design strategy.