中文摘要：

原生质将减少的一些种同类的细菌的宽采纳收割基因差异，增加收割危险到压力，并且减少庄稼生产的稳定性。外国细菌原生质的介绍和利用是拓宽基因差异并且支持变化的期刊代替的一个持续解决方案。基因贡献和经济外国细菌原生质影响，特别地那些美国和 CGIAR (国际农业研究上的商议的组，叫作 CG 系统)材料，在中国的玉米上，生产从 1982～1997 在中国从 20 个主要的生产玉米的省根据变化家谱信息的分析被评估。结果显示到中国玉米生产的美国和 CG 细菌原生质的贡献继续增加，特别地 CG 细菌原生质，它自从 1990 年代，显示出一个快速的增加趋势。如果美国细菌原生质的基因贡献被 1% 增加，玉米产量将在 0.2% 增加(0.01 t 哈 ? 1 ) 。如果 CG 细菌原生质的贡献，有更大的生产潜力，被 1% 增加，玉米产量将由 0.025 t 增加哈 ? 1。一条政策应该被政府在这个方向含有鼓励品种 ers 更集中于 CG 细菌原生质的使用和改进。美国细菌原生质在中国广泛地被利用了以便它能为引起努力的玉米提供细菌原生质资源。

英文摘要：

Wide adoption of a few kinds of homogeneous germplasm would reduce crop genetic diversity, increase crop vulnerability to stresses, and reduce the stability of crop production. The introduction and utilization of foreign germplasm is a sustainable solution for broadening the genetic diversity and promoting periodical replacement of varieties. The genetic contribution and economic impact of foreign germplasm, particularly those of US and CGIAR （Consultative Group on International Agricultural Research, referred to as the CG system） materials, on China＇s maize production are evaluated on the basis of an analysis of variety pedigree information from 20 major maize-producing provinces in China from 1982 to 1997. The results indicated that the contribution of US and CG germplasm to Chinese maize production continues to increase, particularly CG germplasm, which has shown a rapid increasing trend since the 1990s. If the genetic contribution of US germplasm is increased by 1%, maize yield will gain by 0.2% （0.01 t ha^-1）. If contribution of CG germplasm, which has greater production potential, is increased by 1%, maize yield will gain by 0.025 t ha^-1. A policy should be implicated by the government in this direction to encourage breeders to focus more on the use and improvement of CG germplasm. The US germplasm has been utilized extensively in China so that it can offer germplasm resources for maize breeding efforts.