Types and features of crops
Crops are grouped by what we use.
- Cereals (wheat, rice, maize): grasses with starchy grains; the main energy food.
- Pulses (gram, moong, tur): seeds rich in protein. Their roots have nodules where helpful bacteria turn air nitrogen into plant food, so pulses make the soil richer.
- Oilseeds (mustard, groundnut, soybean): seeds that give oil.
- Root and tuber crops (carrot, potato): the food is stored underground.
- Vegetables and fruits (tomato, spinach, mango): leaves, flowers, fruits for vitamins and minerals.
- Fibre and cash crops (cotton, jute, sugarcane): grown mainly for sale.
Some are annual (one season), some biennial (two years) and some perennial (many years, like mango).
Crop growth and physiology
A seed germinates when it gets water, air and warmth. The first root and shoot come out (seedling). Leaves grow, then flowers, which are pollinated, and fruits with new seeds form.
Two jobs run inside every green plant:
- Photosynthesis in leaves: carbon dioxide + water + sunlight gives sugar (food) and oxygen.
- Respiration in all living cells: food + oxygen gives energy for growth.
Roots take up water and minerals. Water also leaves through leaf pores (transpiration), which pulls more water up and cools the plant. A plant grows well when photosynthesis makes more food than respiration uses.
Cultivation environment and growth regulation
Growth depends on temperature, light, water, air, soil and nutrients. Every crop has a best range. Wheat likes cool weather; rice likes warm wet fields.
Farmers regulate growth:
- Irrigation and drainage give the right water.
- Fertiliser and compost give nutrients.
- Greenhouse, polytunnel, shade net, mulch control temperature and light.
- Pruning and thinning remove extra shoots or plants so the rest get more light and food.
- Sowing time is chosen so the crop meets the right weather.
Breeding and propagation
Breeding makes better varieties. Breeders cross plants with useful traits (for example big fruit, short stem, disease resistance), then select the best offspring over several seasons. Modern tools such as tissue culture and gene tools can speed this up.
Propagation means making new plants.
- By seed (sexual): offspring differ a little from the parents.
- Vegetative (asexual): cuttings (sugarcane, rose), grafting (mango), layering, tubers (potato), runners. Every new plant is a copy of the parent and fruits early.
Try it
Soak a few gram seeds overnight, wrap them in a wet cloth, and look every day. Draw the root and shoot. Then in the 3D move temperature to 5 and to 40 and note what happens to the growth speed.
Key formulas and definitions
- Photosynthesis: CO2 + water + light → sugar + oxygen
- Respiration: sugar + oxygen → energy + CO2 + water
- Growth is best near the optimum of each factor (for the 3D plant: about 25 °C and 50% water)
- Life cycle: seed → seedling → flower → fruit → seed
Worked examples
1. Classify: wheat, chana, carrot, tomato, mustard.
Wheat: cereal. Chana: pulse. Carrot: root crop. Tomato: fruit vegetable. Mustard: oilseed.
2. Why are pulses often grown after a cereal crop?
Pulse roots have nodules with bacteria that add nitrogen to the soil. The next crop then finds more food in the soil.
3. In the greenhouse it is 25 °C inside while the outside is 38 °C. Is growth faster inside? Why?
Yes. 25 °C is the best temperature for this plant, while 38 °C is too hot and slows growth.
4. A gardener wants every new rose plant to be exactly like the best one. What method?
Vegetative propagation, such as a cutting. It copies the parent. Seeds would give plants that differ from it.
Common mistakes
- Thinking more water or more heat always means faster growth. Every plant has a best range.
- Mixing up photosynthesis and respiration. Photosynthesis makes food in light; respiration releases energy all day and night.
- Saying a cutting is a seed. A cutting is a piece of stem, root or leaf and gives an exact copy.
- Believing pulses use up soil nitrogen. Their root nodules actually add it.