Various approaches have been used to improve the performance of adapted indigenous stock, including cross-breeding and upgrading through back-crossing with improved breeds, and within-line selection.

已有多种方法被用于提高地方良种的性能，包括杂交育种，以及通过与良种的回交和品系内选育进行的品种改良。

youdao

The ratio of polyploid produced was 87. 5 %, which has shown that crossing combination between Dayali and Pingguoli has special value in pear polyploid breeding.

多倍体出现率为87．5％，表明大鸭梨与苹果梨杂交组合在多倍体育种中具有特殊价值。

youdao

The concept and classification of crop resistance to diseases and pests and the breeding ways including crossing breeding and modern biotechnology application were introduced.

综述了农作物抗病虫性的概念和分类，以及抗病虫育种的途径，包括常规育种和应用生物技术育种的方法。

youdao