Model Answer
0 min readIntroduction
Mass selection is a traditional and widely used plant breeding technique, especially beneficial for self-pollinated crops like rice, wheat, and groundnut. It involves selecting a population of plants based on their overall phenotypic expression – appearance and performance – and using seeds from the best individuals to form the next generation. This method is simpler and less expensive than pedigree or progeny selection, making it accessible to resource-constrained farmers and breeders. The process aims to gradually improve desirable traits over several generations, though its effectiveness is inherently linked to the heritability of those traits.
What is Mass Selection?
Mass selection is a phenotypic selection method primarily employed in self-pollinating crops. It involves identifying and selecting plants that exhibit the desired characteristics (e.g., high yield, disease resistance) and collecting seeds from them to form the next generation. This process is repeated over several cycles, with each cycle theoretically improving the overall genetic makeup of the population.
Applications in Self-Pollinated Crops
Self-pollinating crops are ideally suited for mass selection because self-pollination ensures that the offspring largely resemble the parent plant. This minimizes the influence of genetic recombination and allows breeders to directly select for desirable traits. Examples include:
- Rice: Improving grain yield and disease resistance.
- Wheat: Selection for higher protein content and improved straw strength.
- Groundnut: Enhancing oil content and disease tolerance.
- Chickpea: Selection for drought tolerance and improved pod borer resistance.
Merits of Mass Selection
- Simplicity & Low Cost: Requires minimal infrastructure and expertise.
- Rapid Cycle Time: Can be implemented quickly, allowing for faster improvement.
- Accessibility: Suitable for farmers and breeders with limited resources.
- Adaptation to Local Conditions: Favors plants well-adapted to the specific environment.
- Wide Genetic Base: Selection from a larger population maintains a broader genetic base compared to pedigree selection.
Demerits of Mass Selection
- Limited Genetic Gain: Less effective than pedigree or progeny selection because it doesn't account for individual plant's genetic contribution.
- Accumulation of Undesirable Traits: May inadvertently select for plants with undesirable traits linked to the desirable ones.
- Dependence on Phenotype: Selection is based solely on observable traits, which may not accurately reflect the underlying genetic potential.
- Requires Large Population Size: To ensure sufficient genetic variation for selection. Smaller populations may lead to genetic drift.
- Time Consuming: Requires multiple cycles of selection to achieve significant improvement.
| Feature | Mass Selection |
|---|---|
| Selection Basis | Phenotype (Observable traits) |
| Genetic Gain | Moderate |
| Cost | Low |
| Complexity | Simple |
Conclusion
Mass selection remains a valuable technique for improving self-pollinated crops, particularly in resource-limited settings. While it offers simplicity and accessibility, its limited genetic gain necessitates careful consideration of its limitations. Combining mass selection with other techniques, like marker-assisted selection, can potentially enhance its effectiveness and accelerate the breeding process for achieving desired improvements in crop characteristics. Ultimately, its continued relevance lies in its ease of implementation and contribution to local food security.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.