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导致品种种性退化的原因有两个:一个是包括趋向凋落和趋向变种的品种种性内自身生活力的衰退,消减其适应机能,或产生机能突变而失去品种原有的典型性;另一个是有害因子(包括致病生理小种、害虫及不利其繁衍的各种生物因子)对品种适应机能的适应性,或者说具有一定适应机能的品种对有害因子变异的不适性.促使有害因子加强或增生其破坏力、或者产生新的能害于该品种的有害因子。这两种原因综合作用的结果,表现为品种的抗性减弱,丰产性降低,品质变劣,形态变化.由此趋于淘汰,或者突变形成新的种群. 提纯复壮能恢复品种原有的生活力,但不能消除有害因子对其适应机能的适应。所以,提纯复壮在一定限度内能延长某个品种的寿命,使之发挥较
There are two reasons that lead to the degeneration of the breed: one is the recession of its own vitality, including its tendency to fall and the variety that tends to the breed, its adaptation function is reduced, or the mutation of function is caused to lose its original typicality; the other Is harmful factors (including pathogenic races, pests and unfavorable multiplication of various biological factors) to adapt to the adaptability of varieties, or adapt to a certain adaptability of varieties of harmful factors variation discomfort Promote the strengthening of harmful factors Or increase its destructive power, or produce new harmful species that can harm the species. The combined effect of these two reasons, the performance of the varieties of resistance weakened, reduced yield, quality deterioration, morphological changes .To be eliminated, or mutation to form a new population.Recovery and rehabilitation can restore the original varieties of life Force, but can not eliminate the harmful factors to adapt to their adaptive function. Therefore, the purification and rejuvenation within a certain limit to extend the life of a species, make it play more