Question
What are the three main methods of crop improvement? How does cross-breeding (hybridisation) help in developing better crop varieties?
(CBSE Class 9 — Improvement in Food Resources)
Food Resource Improvement Methods
flowchart TD
A["Improvement in Food Resources"] --> B["Crop Improvement"]
A --> C["Animal Husbandry"]
A --> D["Fisheries"]
B --> B1["Hybridisation"]
B --> B2["GM Crops"]
B --> B3["Manure & Fertilisers"]
B --> B4["Irrigation"]
B --> B5["Crop Protection"]
C --> C1["Cattle farming (milk, draught)"]
C --> C2["Poultry farming (eggs, meat)"]
C --> C3["Fish farming (freshwater, marine)"]
B1 --> E["Cross between: varieties, genera, species"]
D --> D1["Mariculture + Aquaculture"]Solution — Step by Step
1. Crop variety improvement — Developing new varieties through hybridisation or genetic modification that have desirable traits: higher yield, disease resistance, shorter maturity period, wider adaptability, and better quality.
2. Crop production management — Improving how crops are grown: better irrigation (drip, sprinkler), balanced use of manure and fertilisers, mixed cropping, intercropping, and crop rotation.
3. Crop protection management — Protecting crops from pests (insects), diseases (fungi, bacteria), and weeds. Methods include pesticides, biological control, proper storage, and fumigation.
Hybridisation is crossing two genetically different plants to combine their desirable traits in the offspring.
Types of hybridisation:
- Intervarietal — Between two different varieties of the same species (e.g., a high-yield wheat variety crossed with a disease-resistant wheat variety)
- Interspecific — Between two different species of the same genus
- Intergeneric — Between plants of two different genera (rare, difficult)
Example: India’s Green Revolution in the 1960s used hybrid varieties of wheat (developed by Norman Borlaug) and rice (IR-8) that dramatically increased yields.
| Trait | Why Important | Example |
|---|---|---|
| Higher yield | More food per hectare | HYV wheat, rice |
| Disease resistance | Reduces crop loss, less pesticide needed | Blight-resistant potato |
| Shorter maturation | Allows more crop cycles per year | Short-duration paddy |
| Wider adaptability | Grows in different soils, climates | Drought-tolerant millet |
| Improved quality | Better nutrition, taste, shelf life | Protein-rich pulses |
| Fertiliser responsive | Produces more with fertiliser input | Green Revolution varieties |
Why This Works
Food demand increases with population, but agricultural land is limited. The only way to produce more food from the same land is to improve either the crop itself (better varieties) or how it is grown (better management). Hybridisation works because combining genes from two parents can produce offspring that are better than either parent — a phenomenon called hybrid vigour (heterosis).
Alternative Method — Animal Husbandry Overview
For animal protein sources:
Cattle farming:
- Milch breeds (milk production): Sahiwal, Jersey
- Draught breeds (farm work): Nageri, Hallikar
- Improvement through cross-breeding exotic breeds (Jersey, Holstein) with Indian breeds
Poultry farming:
- Broilers (meat) and layers (eggs)
- Improved varieties: White Leghorn (layer), Aseel crossed with foreign breeds
Fisheries:
- Freshwater: Rohu, Catla, Mrigal (Indian major carps)
- Marine: Pomfret, Mackerel
- Composite fish culture — Multiple species in the same pond, each feeding at different levels
For CBSE Class 9, the most important terms to define are: hybridisation, GM crops, composite fish culture, organic farming, and mixed cropping vs intercropping. These are frequently asked as 2-mark definition questions. Intercropping means growing two crops simultaneously in alternating rows (e.g., soybean + maize). Mixed cropping means mixing seeds and growing them together in the same field.
Common Mistake
Students confuse mixed cropping with intercropping. Mixed cropping mixes seeds of two or more crops and sows them together (no separate rows) — it reduces risk of total crop failure. Intercropping grows two or more crops in definite row patterns (e.g., soybean in one row, maize in the next) — it maximises yield by using nutrients at different soil levels. CBSE asks the difference directly, and mixing these up costs marks.