为了解决玉米杂交种亲本遗传基础狭窄问题,美国对外来种质和玉米带种质的重组十分重视。有益的种质资源能够提供遗传的多样性,但其在育种上价值的大小,则取决于被利用的外来种质的性质和原产地的位置。近年来,我国有些研究单位,已经开始利用热带、亚热带玉米种质,作为组成改良群体和选育自交系的基础材料,有的已取得良好结果。前名作者,1978—1980年在北也门(阿拉伯也门共和国)白脱纳农业试验中心,我国援外农技专家组工作期间,利用当地热带玉米材料开展了直接选育二环系研究。这批早代选系带回国内后,从1981年开始,与中国农 In order to solve the problem of narrow genetic base of maize hybrids, the United States attaches great importance to the reorganization of foreign germplasm and maize germplasm. Beneficial germplasm resources provide genetic diversity, but their value in breeding depends on the nature of the foreign germplasm being exploited and the location of the origin. In recent years, some research institutes in our country have started to utilize tropical and subtropical maize germplasms as the basic materials for forming improved populations and breeding inbred lines, and some have achieved good results. Former author, 1978-1980 Direct breeding of the second ring system was conducted using the local tropical maize material during the work of the White Ratan Agricultural Experiment Center in North Yemen (Yemen Arab Republic) and China’s AAR Team. After these early-generation pick-ups were brought back to China, starting from 1981, they were working with Chinese peasants