[Ineffectiveness of the back cross method in selecting hemp for heterosis].

In the back crossings the heretability caused by the additive effect of the genes predominates. The selection on the characters controlled by the additive genes leads to the homozygosis increase of the population and to the reduced vitality of the plants. The repeated crossing of the heterozygous hybrid plants with the parental form homozygous according to the recessive gene increases the quota of the genes of the latter. It results in the intermediate type of inheritance for all the elements of the back crossing hybrids productivity.