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The following points highlight the five main steps involved in breeding a new genetic variety of a crop. The steps are: 1. Collection of Variability 2. Evaluation and Selection of Parents 3. Cross Hybridisation among the Selected Parents 4. Selection and Testing of Superior Recombinants 5. Testing, Release and Commercialisation of New Cultivars.
Step # 1. Collection of Variability:
Genetic variability is the root of any breeding programme. Pre-existing genetic variability available in wild varieties, species and relatives of many crop species is collected and preserved.
Evaluation of their characteristics is a pre-requisite for the effective exploitation of natural genes available in the populations. The entire collection of plant/seeds having all diverse alleles for all genes in a given crop is called germplasm collection.
Step # 2. Evaluation and Selection of Parents:
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It is carried out by evaluating germplasm to identify plants with desirable combination of characters. The selected plants are multiplied and hybridised by self-pollination. Pure-lines are created, whenever desired and possible.
Step # 3. Cross Hybridisation among the Selected Parents:
It is possible by cross hybridising the two parents to produce hybrids that genetically combine the desired characters in one plant.
It is a time consuming and tedious process as it involves collection of pollen grains from the desired plants and other pollination techniques to incorporate desired traits.
It is also not necessary that the hybrids combine desired characters. The chances of desirable combination is usually only one in few hundred to a thousand crosses carried out.
Step # 4. Selection and Testing of Superior Recombinants:
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This step consists of selection of plants among the progeny of the hybrids with desired combination of characters. It yields plants that are superior to both of the parents. This is known as hybrid vigour/heterosis. They are self-pollinated for several generations till they reach a state of uniformity or homozygosity, so that characters will not segregate in the progeny.
Step # 5. Testing, Release and Commercialisation of New Cultivars:
Evaluation is done for newly selected lines for their yield and other agronomic traits of quality, disease resistance, etc. Selected plants are grown in research fields and their performance is recorded under ideal fertiliser applications, irrigation and other crop management practices.
Testing of hybrid line is done in farmer’s field after evaluation. After testing, the crop is grown at different locations in the country with different agro-climatic zones for at least three growing seasons.
The tested material is evaluated in comparison to the best available local crop cultivar used as reference cultivar.
Release of tested material is done in bulk after selection and certification.
