四、玉米自交系的繁殖和保纯山西省常年玉米种植面积约1000万亩,以单交种为主,每年杂交种种子生产任务基本稳定在2500万公斤。由于没有实现种子生产的企业化,良种繁育体制和检验制度不健全,种子生产的专业技术还不普及,大量 Fourth, the propagation and conservation of maize Inbred lines of perennial corn in Shanxi Province about 10 million mu of cultivated area, with a single cross-species-based, annual hybrid seed production tasks basically stable at 25 million kilograms. Because of the lack of enterpriseization of seed production, the imperfect breeding system and testing system, the specialized techniques of seed production are not yet widespread,