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近年来,由于种种原因,我市亲本繁殖质量有下降的趋势。一、引起亲本质量下降的原因 (一)自交系本身的分离和基因突变玉米是异花授粉作物,基因型的杂合程度较高,在选育玉米自交系的过程中,虽经连续多代自交,但不可能达到完全纯合,总是有一些杂合的基因存在,后代就必然出现分离。另外基因突变又是随时可能发生的,但是机率不大。因此,既使原种的纯度很高,且在严格隔离条件下,也会产生一些微小的差异。随着繁殖世代的增加,这些差异就会逐渐积累起来,自交系就会由纯变杂。
In recent years, due to various reasons, the reproductive quality of our city has a downward trend. First, the cause of the decline in the quality of the parent (a) the inbred line of their own isolation and genetic mutation Maize cross-pollinated crops, genotypes of a high degree of heterogeneity in the process of breeding of maize inbred lines, though continuous Self generations at many generations, but it is impossible to achieve complete homozygosity, there are always some heterozygous genes exist, the descendants will inevitably appear isolated. In addition gene mutations are likely to occur at any time, but the probability is not. Therefore, even if the original species of high purity, and in strict isolation conditions, there will be some minor differences. As the breeding age increases, these differences will gradually accumulate, and inbred lines will be transformed from pure ones.