二十世纪以来人们的研究发现,在植物界的一个属里,种与种之间在控制种性的遗传物质染色体的数目上,常常存在倍数关系。例如在小麦属里,野生小麦的体细胞具有14条染色体,系原始的二倍体小麦,产量很低但抗逆性强,目前只收集供做育种的亲本材料;硬粒小麦具有28条染色体,是介于野生型和栽培型之间古老的四倍体,产量 Studies from the 20th century have found that in one genus of the plant kingdom there is often a multiple relationship between species and species in controlling the number of genetic material chromosomes. For example, in wheat, the somatic cells of wild wheat have 14 chromosomes, the original diploid wheat, with low yield but strong resistance. Currently, only the parent material for breeding is collected; Durum wheat has 28 chromosomes , Is an ancient tetraploid between wild-type and cultivated yield