Q.Describe briefly various steps of plant breeding methods.

Step 1. Hybridization, as a five-step programme. (i) Collection of variability — assembling a germplasm collection of wild relatives and existing varieties, conserved in situ (forests/reserves) or ex situ (botanical gardens/seed banks).

(ii) Evaluation and selection of parents — screening the germplasm for desirable, complementary traits, then self-pollinating each chosen parent for three to four generations to make it homozygous.

(iii) Hybridization proper — choosing the more desirable variety as the female (recurrent) parent, emasculating its flowers, artificially cross-pollinating with pollen from the male (donor) parent, and bagging/tagging the flower, yielding the F1 hybrid generation.

(iv) Selection and testing of superior recombinants — selfing the best F1 hybrids for several generations until the desired traits become homozygous and stop segregating.

(v) Testing, release and commercialisation — evaluating the stabilised lines under controlled conditions and then across field trials in different agro-climatic zones for at least three seasons, before releasing the new variety to farmers.

Step 2. Mutation breeding. Seeds or seedlings are exposed to a physical mutagen (high temperature, elevated CO2, X-rays, UV rays) or a chemical mutagen (nitrous acid, EMS, mustard gas, colchicine) to induce gene mutations or chromosomal aberrations, and the treated material is then screened for useful new traits (disease resistance, pest resistance, higher yield), exactly as in the hybridization pipeline's selection steps. …

Walking through the hybridization programme step by step, then summarising mutation breeding a …

• Describing only hybridization when the question asks for 'various methods' (plural) — mutation breeding, and at least a mention of the other named methods, should also be included. …