Question

With advancements in genetics, molecular biology and tissue culture, new traits have been incorporated into crop plants. Explain the main steps in breeding a new genetic variety of a crop

Answer 1

Main steps in breeding a new genetic variety of a crop:

(i) Collection of variability: Germplasm is the total of all the alleles of the genes present in a crop and its related species. Collection and preservation of all the different wild varieties, species and relatives of the cultivated species is a pre-requisite for effective exploitation of natural genes available in a population. The entire collection of plants/seeds 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 combination of characters. Selection of parents is picking up seeds of only those plants for multiplication which have the desired traits. The selected plants are multiplied and used in the process of hybridisation. Pure lines are created wherever desirable and possible.

(iii) Cross hybridisation among the selected parents: Hybridisation is the most common method of creating genetic variation. Hybridisation is crossing of two or more types of plants to produce their traits together in the progeny which helps bring about useful genetic or heritable variations of two or more lines together. For example, high protein quality of one parent may need to be combined with disease resistance from another parent.

(iv) Selection and testing of superior recombinants: The hybrids having desired characters are selected from the progeny and then self-pollinated for several generations to make them homozygous.

(v) Testing, release and commercialisation of new cultivars: The selected plants are then evaluated for their yield and other agronomic traits of quality and disease resistance by growing them in research fields under ideal fertiliser application, irrigation and other crop management practices. Testing is done in research fields for at least three growing seasons and
then grown in different parts of the country. After thoroughly testing, the seeds of selected variety are recommended to the farmers for large-scale cultivation.