一、研究的目的和意义利用杂种优势,是提高玉米产量的重要措施之一。特别是单交种,整齐度高,杂种优势大,隔离区少,制种较简单。但由于单交种是由自交系配成的,自交系的生长势弱,产量低,一股单交制种产量为每亩150—200斤左右,因而繁殖系数低,种子成本高。近几年,我省玉米播种面积 First, the purpose and significance of the study The use of heterosis, is one of the important measures to improve corn production. In particular, a single cross-species, high uniformity, heterosis, less isolation, seed production is relatively simple. However, since the single cross is bred from inbred lines, inbred lines have a weak growth potential and low yield. The output of a single cross is about 150-200 kg per acre. Therefore, the breeding coefficient is low and the cost of the seeds is high. In recent years, our province corn sown area