Q.Give a detailed account of a classical plant breeding programme, describing each step (germplasm collection, evaluation and selection of parents, cross-hybridization, selection and testing of superior recombinants, and testing/release of new varieties), and illustrate your answer with at least two Indian examples of crop varieties developed by plant breeding.
A classical plant breeding programme proceeds through a fixed, connected sequence of steps.
Collection of genetic variability: the programme begins by assembling a germplasm collection -- the sum total of the different alleles present in the crop species and its wild relatives, gathered and conserved as seed in a gene bank or as living field collections -- giving breeders the widest possible pool of traits, including rare traits (such as an unusual disease resistance) found only in a wild relative.
Evaluation and selection of parents: the assembled germplasm is evaluated to identify plants carrying the specific traits the programme targets, and the best of these are selected as parents, often first established as genetically uniform pure lines so their individual contributions are well characterised.
Cross-hybridization: the selected parents, each strong in a different desired trait, are cross-pollinated to combine their traits in hybrid offspring. In a bisexual flower used as the female parent, this requires emasculation (removing the anthers before they shed pollen, to prevent self-pollination) and bagging (covering the flower to exclude foreign pollen) until the breeder deliberately applies pollen from the chosen male parent.
Selection and testing of superior recombinants: the resulting hybrid offspring segregate into many different combinations of parental traits; the breeder selects the individual plants -- the superior recombinants -- that combine the desired traits most successfully, and multiplies and re-tests them over further generations until the line breeds true.
Testing and release: finally, the most promising lines are tested for yield, quality and resistance at multiple locations over several growing seasons, compared against currently grown varieties, and, if they perform reliably better, formally released and notified for cultivation.
Two Indian examples illustrate this whole sequence in practice. The wheat variety Himgiri was developed through exactly this process to resist leaf and stripe rust, two major fungal diseases of wheat in India's hill wheat-growing tracts. In sugarcane, breeders crossed the thin-stemmed but hardy North Indian species Saccharum barberi with the thick-stemmed, high-sugar-yield tropical species Saccharum officinarum, producing hybrid canes that combine the higher sugar yield of the tropical parent with the hardiness needed for North Indian growing conditions -- a direct, real example of cross-hybridization and selection delivering both higher yield and wider adaptability at once.
[!ANSWER]
Five steps -- germplasm collection, parent selection, cross-hybridization, selection of superior recombinants, testing and release -- illustrated by Himgiri wheat (rust resistance) and North Indian hybrid sugarcane (yield + hardiness).
Unlock everything free for 14 days
- Full step-by-step solutions
- Concept-first explanations
- Methods, shortcuts & mistakes
- PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.