Question

Arrange the following steps of a plant breeding programme in the correct order.

I. Selection and testing of superior recombinants
II. Collection of variability
III. Cross hybridisation between the selected parents
IV. Evaluation and selection of parents
V. Testing, release and commercialisation of new cultivars

Answer 1

Plant breeding is the technique of breeding between plants of desired traits in order to bring about new improved varieties that are better suited for cultivation, give better yield and are resistant to damage by pests or pathogens.

The steps involved are as follows:

• Collection of variability - Germplasm refers to the seeds/plants having all possible alleles for all the genes in a given crop. Collection of the diverse germplasm ensures that plant breeders have the whole range of possible genetic variabilities of a crop plant.
• Evaluation and selection of parents - The whole available germplasm is screened for desirable traits that are to be incorporated into the new variety. The plants chosen as parents are self-pollinated (pollen from the anther of a flower is transferred to the stigma of the same flower or different flower of the same plant) to increase homozygosity (presence of similar alleles for a particular character). This results in the generation of a pure line.
• Cross-hybridisation amongst selected parents - The process of hybridisation involves crossing between two pure line parents having desired characteristics with the help of artificial cross pollination (pollen from the flower of the plant designated as male parent is transferred to the stigma of the flower of the plant designated as female parent). The progeny obtained are called hybrids.
• Selection and testing of recombinants - The seeds produced by only those plants in the progeny, which show the desired combination of superior characteristic(s) of both the parents, are selected for raising the future generation. This process is continued until the whole population exhibits the desired combination of superior characteristic(s).
• Testing, release and commercialisation of new cultivars - The new cultivars are first evaluated for their yield and other desirable qualities like disease resistance and tolerance to environmental stresses (salinity, extreme temperatures, drought). The evaluation is performed by growing them in research fields under conditions like ideal fertiliser application and other crop management practices. Once the new cultivars are grown successfully in the research field, they are now grown in farmer’s fields for at least three growing seasons across different parts of the country representing the various agroclimatic zones. The new cultivar is evaluated in comparison to the best available local crop cultivar (check or reference cultivar) in terms of quality and cost.