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甘薯优良品种在生产上推广以后,随着时间的推移,往往会逐渐混杂退化,丧失原品种的典型性,种性变劣,产量下降。混杂退化原因很复杂:①机械混杂。②自然变异。甘薯品种的异质性很强,在无性繁殖过程中易变。在粗放栽培条件下,劣变较多,如不注意选择,就会引起混杂。③环境不良。如果栽培环境条件不良,良种种性就难以发挥,导致经济性状变劣。④选择不当。长蔓型往往是退化型,人们却习惯选择长蔓剪苗扦插,便加速退化型的传播。⑤长期无性繁殖。这样世代得不到更新复壮会引起衰退。采用单薯选择、分系比较、混系繁殖法生产原种,是个好方法。
After the promotion of sweet potato varieties in production, they often gradually become mixed and degenerate with the passage of time, losing the typicality of the original varieties, deteriorating the seed quality and decreasing the yield. The reasons for mixed degeneration are complex: ① mechanical mixed. ② natural variation. Sweetpotato varieties are highly heterogeneous and mutable during vegetative propagation. In the extensive cultivation conditions, more deterioration, if you do not pay attention to choose, it will cause mixed. ③ bad environment. If the cultivation of poor environmental conditions, good seed variety will be difficult to play, leading to deterioration of economic traits. ④ improper choice. Long-Man-type is often degraded, people are used to choose long-cut cuttings cuttings, they accelerated the spread of degenerative. ⑤ long-term asexual reproduction. This generation can not get renewed and rejuvenated will lead to recession. The use of single-potato selection, compared with the subsystems, mixed breeding reproduction of the original species, is a good way.