What phenomenon is observed when two clean lines cross each other and produce a high-yielding hybrid as a result?

Heterosis is the superiority of children over their parents in terms of productivity, fertility, vitality. It appears only in F1. Heterosis is obtained by pairing homozygous (clean lines), different in the genotype of the parents, so that children have increased heterozygosity. The basis of heterosis is a sharp increase in heterozygosity in first-generation hybrids and the superiority of heterozygotes for certain genes over corresponding homozygotes.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.