Describe various steps in breeding a new genetic variety of a crop.

(A) The main steps in breeding a new genetic variety of a crop are as follows:
$(i)$ Collection of variability: Genetic variability is the root of any breeding programme.
- In many crops,pre-existing genetic variability is available from wild relatives of the crop.
- Collection and preservation of all the different wild varieties,species,and relatives of the cultivated species is a pre-requisite.
The entire collection having all the diverse alleles for all genes in a given crop is called germplasm collection.
$(ii)$ Evaluation and selection of parents: The germplasm is evaluated to identify plants with desirable combinations of characters.
The selected plants are multiplied and used in the process of hybridisation. Purelines are created wherever desirable and possible.
$(iii)$ Cross hybridisation among the selected parents: The desired characters often have to be combined from two different plants (parents).
For example,high protein quality of one parent may need to be combined with disease resistance from another parent. This is possible by cross-hybridising the two parents to produce hybrids that genetically combine the desired characters in one plant.
This is a time-consuming and tedious process since the pollen grains from the desirable plant chosen as the male parent must be collected and placed on the stigma of the flowers selected as the female parent.
Also,it is not necessary that the hybrids combine the desirable characters; usually,only one in a few hundred to a thousand crosses shows the desirable combination.
$(iv)$ Selection and testing of superior recombinants: This step consists of selecting among the progeny of the hybrids those plants that have the desired character combination.
The selection process is crucial to the success of the breeding objective and requires careful scientific evaluation of the progeny.
This step yields plants that are superior to both parents.
- These are self-pollinated for several generations until they reach a state of uniformity so that the characters will not segregate in the progeny.
$(v)$ Testing,release,and commercialisation of new cultivars: The newly selected lines are evaluated for their yield and other agronomic traits of quality,disease resistance,etc.
This evaluation is done by growing these in research fields and recording their performance under ideal fertiliser application,irrigation,and other crop management practices.