How inbreeding depression takes place and how it is to be controlled?

In breeding is the mating of more closely related individuals of the same breed. It increases homozygosity. Inbreeding depression is the main disadvantage of inbreeding that occurs due to continuos inbreeding between closely related species of common ancestry. It reduces the fertility and even the productivity. To overcome this problem selected animals of the breeding population should be mated with unrelated superior animals of the same breed. It is called outcrossing. This helps to restore the yield and fertility of cattle.

Why is self-pollination procedure essential among different progeny hybrids for the selection of new recombinants in plant breeding programme?

Plant breeding is a technique that involves crossbreeding or hybridization between two varieties of plants to obtain and new and better adapted variety. The hybrid thus formed is superior for both the parents. These superior plants are self-pollinated for several generations till they come to a state of unity or homozygosity so that the characters will not separate in the progeny.