Nutrition in Plants

Living organisms require food to obtain energy for various life processes, grow, and repair damaged parts of their bodies. The process of obtaining and utilizing nutrients from food is known as nutrition. Most plants produce their food utilizing raw materials like minerals, carbon dioxide, and water from their surroundings in the presence of sunlight, with a few exceptions relying on other organisms for nutrition. Thus, plants exhibit two major modes of nutrition -

Autotrophic nutrition
Heterotrophic nutrition

Autotrophic Nutrition in Plants

Plants that contain a pigment called chlorophyll can perform photosynthesis. Such plants are referred to as autotrophs as they can synthesize their own food. They use simple inorganic substances as raw materials for the production of food. These plants are also referred to as producers because they are the base of the food chain. Thus, autotrophs provide energy and organic matter for all other living organisms.

Photosynthesis

It is the process by which plants synthesize organic food from carbon dioxide and water in the presence of solar energy. It produces glucose as the primary form of organic food.

Steps in Photosynthesis [a]

Absorption of solar energy
Conversion of light energy into chemical energy
Hydrolysis of water into oxygen and hydrogen
Reduction of carbon dioxide to produce glucose
Glucose is ultimately converted into starch and stored as a food reserve.

All the organisms depend upon the autotrophic plants for their food, directly or indirectly.

Heterotrophic Nutrition in Plants

Plants that lack chlorophyll cannot perform photosynthesis. These plants are referred to as heterotrophs. Thus, derive their requirements of nutrients from other sources, such as from other plants, dead matter or others. The heterotrophic mode of nutrition in plants can be classified into four types [b]-

Parasitic Nutrition

Some heterotrophs actively depend on other organisms and draw nutrition from the host. Thus, the parasitic nutrition harms the host for nutrition. Plants using this mode of nutrition are known as parasites.

Example: Cuscuta reflexa, Cassytha filiformis, etc.

Saprophytic Nutrition

Some heterotrophs derive nutrients from dead and decaying matter in the form of a solution. Plants which use such a mode of nutrition are called saprotrophs. The saprotrophs tend to be pale and whitish.

Example: Monotropa (Indian Pipe) and certain orchids

Symbiotic Nutrition

Some heterotrophs associate with another organism in a mutually beneficial interaction, where the two organisms share shelter and nutrients. Each of the two organisms is known as a symbiont.

Example: Lichen, Mycorrhiza, etc.

Insectivorous or Carnivorous Nutrition

Some autotrophic plants, growing in nitrogen-deficient soil, sometimes obtain nitrogen by consuming insects or small birds.

Example: Dionaea muscipula, Nepenthes sp., etc.

Frequently Asked Questions (FAQs)

Q1. Where do plants get their nutrients from?

Plants get their nutrients from photosynthesis and through absorption through roots. The nutrients dissolve in water and are taken up by plants in the form of ions.

Q2. What is nitrogen fixation?

In leguminous plants, certain nitrogen-fixing bacteria like Rhizobium sp. are present at the root nodules. The bacteria convert atmospheric nitrogen (N₂) into a usable form like ammonia (NH₃).

Q3. Which nutrients do plants need?

The plants require macronutrients and micronutrients for growth. The macronutrients like nitrogen, phosphorus and others are required in larger quantities compared to the micronutrients like iron, manganese, zinc and others.