Nutrition in Plants
Nutrition is the process of taking in food and utilizing it for growth, repair, and other life processes. Plants are unique as they are primary producers in the food chain.
Autotrophic Nutrition and Photosynthesis
Green plants are called autotrophs because they synthesize their own food. The process is called photosynthesis. It occurs in the green leaves using chlorophyll, sunlight, carbon dioxide, and water.
- Raw Materials: Carbon dioxide, Water, Sunlight, Chlorophyll.
- Equation: Carbon dioxide + Water → Glucose + Oxygen (in the presence of sunlight and chlorophyll).
- Site: Chloroplasts in leaf cells.
- Products: Glucose (food) and Oxygen (released into the air).
Other Modes of Nutrition in Plants
Not all plants are autotrophs. Some have different ways to get nutrients.
Heterotrophic Nutrition
Plants that cannot prepare their own food are called heterotrophs.
- Parasitic Plants: Derive food from other living plants (host). Example: Cuscuta (Amarbel).
- Saprotrophic Nutrition: Organisms feed on dead and decaying matter. Example: Fungi like mushrooms. They are called saprotrophs.
- Insectivorous Plants: Plants that trap insects for nitrogen. Example: Pitcher plant, Venus flytrap.
Symbiosis - An Interdependent Relationship
Some plants live in a mutually beneficial relationship with other organisms. This is called symbiosis.
- Example: Lichens (algae and fungus live together).
- Example: Rhizobium bacteria in root nodules of legumes (like peas, beans). Bacteria fix atmospheric nitrogen for the plant, and the plant provides food and shelter.
How Nutrients are Replenished in Soil
Plants absorb minerals and nitrogen from the soil. Fertilisers and manures add nutrients back. Rhizobium bacteria also enrich soil nitrogen. Farmers rotate crops (like wheat with pulses) to maintain soil fertility.
Key Terms and Definitions
- Chlorophyll: Green pigment in leaves.
- Stomata: Tiny pores on leaves for gas exchange.
- Host: Plant on which a parasite climbs.
- Nutrients: Components of food like carbohydrates, proteins, fats, vitamins, minerals.
