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所谓退化,就是指品种的特征特性(即遗传性)发生了不利于栽培、不利于生产的改变。所谓混杂,就是一个品种里混进了其他品种的现象。混杂势必导致退化,退化势必引起混杂。因而,常常用混杂退化来说明品种生活力的减退。品种一经混杂退化,就不可避免地要给生产上带来损失。据1980年和1982年我们的调查表明,一般大田用种的杂株率为7.8—16.4%,有的竟高达30.4—42.4%;白发病增加1.0%,红叶病增加1.9%;株高降低8.5厘米,穗长减少7.3厘米,穗粒重减少9.6克,比原种平均减产6.7—10.4%,有的高达18.7%。
The so-called degradation, refers to the characteristics of varieties (ie, genetic) occurred in the adverse of cultivation, is not conducive to changes in production. The so-called hybrid, is a variety of mixed with other species in the phenomenon. Mixed will inevitably lead to degradation, degradation is bound to cause mixed. Thus, mixed degradation is often used to illustrate the decline in breed viability. Once the varieties are mixed and degenerated, it will inevitably bring losses to the production. According to our survey conducted in 1980 and 1982, the rate of heterosis in common fields was 7.8-16.4%, up to 30.4-42.4% in some fields, 1.0% in white diseases, 1.9% in leaf diseases, and 8.5% in plant height Cm, spike length decreased 7.3 cm, grain weight reduction of 9.6 grams, an average reduction of 6.7-10.4% than the original species, some as high as 18.7%.