Mutation Breeding

B. Mutation Breeding : Mutation is a sudden, heritable change in an organism's genotype. It can arise naturally, or it can be deliberately induced in a breeding programme by exposing seeds or seedlings to a mutagen, and mutation breeding is the deliberate use of such induced mutations to create new, improved crop varieties.

Mutagens fall into two broad classes. Natural (physical) mutagens include high temperature, a high concentration of carbon dioxide, X-rays and UV rays. Chemical mutagens include nitrous acid, EMS (ethyl methyl sulphonate), mustard gas and colchicine. In practice, seeds or seedlings are irradiated — for example with cobalt-60, or exposed to UV lamps or X-ray machines — and these mutagens act by causing gene mutations (changes within a single gene) and chromosomal aberrations (larger-scale changes in chromosome structure or number). …