摘要： 针对我国高寒山区积温少、无霜期短，无杂交玉米，从搜集超早熟玉米种质资源入手，利用超早熟、抗寒冷玉米珍贵种质资源“坝上火玉米”，导入高配合力、优良农艺性状遗传基因，选育出极早熟优良自交系“承18”，总结出选育一环系和二环系相结合的顶交玉米育种的新途径，并分析该系的特点和育成经验，可为今后选育极早熟玉米自交系提供借鉴。

关键词: 玉米, 自交系, 极早熟品种, 选育

Abstract: Aiming at the problem that no hybrid maize is grown in high latitudes of China because of less accumulated temperature and shorter frost-free period, we began the breeding work, starting with collecting the germplasm resources of surplus-early maize. The genes of high combining ability and superior agronomic characters were transfered to " Bashang Huoyumi", a valuable germplasm of ultra-early and cold-resistant maize-the superior surplus-early self-line "Cheng. 18" was bred out. Summarizing the new approach of top-cross maize breeding with the combination of first cycle and second cycle and analyzing the characteristics of the very line and the successful experiences in breeding will help the breeding work for surplus-early maize self line in the future.

Key words: Maize, Self-line, Surplus -early mature