一个红苕良种投放生产使用后,在分户承包生产责任制条件下,由于农户缺乏红苕选优留种、防杂保纯的科学常识,一般都是“种”、“粮”不分,几年之后就出现了品种混杂退化,导致产量下降。我省80年代初期推广的川薯27,徐薯18,目前大面积生产上均不同程度的出现了混杂、退化现象。据西充、南充等县调查,多数田块除了主栽品种外,均混杂有其它品种2—3个,杂株率达5—15％。 After a red-bred elite is put into production and used, under the condition of household-based contract responsibility system, due to lack of scientific knowledge of selecting elite and preventing hybrids from farmers, they are generally classified as “species” and “grain” After the emergence of a variety of hybrid degradation, resulting in decreased production. In the early 1980s in our province, Sichuan-Shuanzuo 27 and Xushu 18 were promoted. At present, the phenomenon of promiscuous and degenerated appeared in different degrees on large-scale production. According to the survey of Xicheng and Nanchong counties, most of the plots were all mixed with 2-3 varieties except for the main cultivars, with a heterozygosity rate of 5-15%.