对小麦 (Triticumaestivum)和无融合生殖小麦草 (Elymusrectisetus)的杂种后代 (BC2 F2 )生物学特性和根尖染色体数目变化情况进行了的研究。结果表明 ,BC2 F2 的生物学特性处于小麦和小麦草之间 ,但更趋向于小麦 ,这是由于杂交后代经 2次回交所致。根尖染色体检查发现 ,BC2 F2 的体细胞染色体数目存在 1个很大的变异范围 ,从 2 9条到 6 9条不等 ,但大部分细胞内的染色体数目是 42条。杂种后代的体细胞染色体数目的变化一方面与远缘杂交有关 ,另一方面可能与无融合生殖具有一定的联系 The biological characteristics and the number of apical chromosomes of hybrids (BC2 F2) of Triticum aestivum and Elymusrectisetus were studied. The results showed that the biological characteristics of BC2 F2 lie between wheat and wheat grass but are more likely to occur in wheat due to 2 backcrosses of crossing progeny. Apical chromosome examination revealed that the number of somatic chromosomes in BC2 F2 ranged from 29 to 69, but the number of chromosomes in most of the cells was 42. The number of somatic chromosomes in hybrid offspring may be related to distant hybridization on the one hand and may be related to apomixis on the other hand