杂种优势的利用,在玉米生产中发展得最快、最普及,对提高玉米产量起了重要作用。但应看到,生产上利用的大多数优良杂交种,它们的亲本只有少数几个骨干自交系,遗传基础贫乏。如果仍用常规育种方法,继续选育自交系,只能使遗传基础愈选愈窄,很难取得突破性成效。七十年代以来,我国育种工作者,普遍重视群体改良工作,使人为创造的品种群体,成为遗传基础广泛的基因库,积累和贮藏 Utilization of heterosis, the fastest growing in the production of corn, the most popular, to improve the yield of corn played an important role. However, it should be noted that most of the fine hybrids used in production have only a few key inbred lines in their parents, with a poor genetic basis. If you still use conventional breeding methods, continue to breed inbred lines, only the genetic basis of the more narrow choice, it is difficult to achieve breakthrough results. Since the 1970s, breeders in our country have generally attached great importance to the work of group improvement so that the breed groups artificially created have become a gene pool with extensive gene base, accumulation and storage