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十九世纪三十年代以来,人类利用自然传粉的品种资源,分离出许多优良的自交系,奠定了现代玉米育种的基础.但至六十年代初期世界各国纯系育种工作进展有所迟缓.而杂交种的利用在生产上也出现了一些问题.例如1970年美国生产上利用的T型细胞质雄性不孕系杂交种,由于受到T小种的侵袭,一年减产玉米竟达165亿公斤.产生上述一些问题的原因主要有二,一是育种种质资源枯竭,人们在大量开发选系的同时,
Since the 1930s, mankind has made use of natural pollination resources to isolate many excellent inbred lines and laid the foundation for modern corn breeding. However, the progress of purebred breeding in the world in the early 1960s has been slow. The use of hybrids in the production of some problems have emerged, for example, the United States in the production of T-type cytoplasm male infertility hybrids, due to the invasion of T race, a year as much as 16.5 billion kilograms of corn. There are two main reasons for the above problems, one is the exhaustion of breeding germplasm resources, and at the same time that people are developing a large number of selected germplasms,