目前,我国玉米杂种优势利用正处于“爬坡阶段”。要造育出超过现有推广的优良杂交种,首先必须育成相应基因型的优良自交系。为此,国内各育种单位普遍重视人工创造“基础群体”,采用轮回选择,以提高自交系的选育水平,达到育种目的。在玉米育种工作中普遍存在和急待解决的问题是:自交系的亲缘关系混乱和接近, At present, the utilization of maize heterosis in China is at a “climbing stage”. To breed more than the current promotion of good hybrids, we must first breed the corresponding genotypes of the fine inbred lines. To this end, the domestic breeding units generally attach importance to artificially creating “basic groups” and adopt the option of “round-robin” to raise the level of breeding of inbred lines and achieve breeding purposes. Problems that are ubiquitous and urgent to be solved in maize breeding are: the genetic relationship of inbred lines is confused and close,