Answer:
Plant breeding programmes are carried out in a very systematic way, world- wide in government institutions and in many commercial companies. The main steps in breeding a new genetic variety of a crop are as follows:
1. Collection of variability:
Genetic variability is the main element of any breeding programme. In many crops genetic variability which is pre- existing, is available from wild relatives of the crop. Collection and preservation of all the different wild varieties, species and relatives also of the cultivated species followed by their evaluation for their characteristics which is a pre- requisite for effective exploitation of natural genes that is available in the populations.
The entire collection of plants or seeds, having all the diversified alleles for all genes in a given crop is known as germplasm collection.
2. Evaluation and selection of parents:
The germplasm is evaluated to identify the plants with desirable combination of characters. The selected plants are multiplied and then used in the hybridization process. Purelines are created wherever desired and possible.
3. Cross hybridization among the selected parents:
The desired characters have very often to be combined from two different parent plants, for e.g. high protein quality of one parent may need to be combines with the disease resistance from another parent.
This process is possible by cross hybridizing the two parents to produce the hybrids that genetically combine the desired characters in a single plant. This is a very time consuming process since the pollen grains from the desirable plants chosen as male parent, have to be collected and placed on the stigma of the flowers that is selected as female parent.
Also, it is not necessary that the hybrids should combine the required characters, usually only in few hundred to a thousand crosses too shows the desirable combination.
4. Selection and testing of superior recombinants:
This step consists of selecting among the progeny of the hybrids to those plants that contains the desired or required character combinations. The selection process is very crucial or important for the success of the breeding objectives and requires careful scientific evaluation of the progeny. This step yields the plants which are superior for both the parents and they are self -pollinated for several generation till they reach a state of uniformity or equilibrium, so that the characters will not segregate in the progeny.
5. Testing, release and commercialization of new cultivars:
The newly selected lines are evaluated and selected for their yield and other agronomic traits of quality, disease resistance etc. This evaluation is done by the growth of these in the research fields and by recording their performance under ideal or actual fertilizer application, irrigation and other crop management practices.
The evaluation in research fields is followed by testing the materials in farmer’s fields for at least three growing seasons on the several locations in country that represents all the agro-climatic zones when the crop is usually grown. The material is evaluated in comparison to the best available local crop and after this evaluation the variety can be released for the farmers.
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