Nutrition in Plants

Nutrition is the mode of taking food by an organism and its utilisation by the body. The growth in living beings happens due to the nutrition that they intake from their food. Similarly, plants have very different nutrition requirements than humans. The fun fact is that plants make their own food by using inorganic (matter of non-living things) substances such as sunlight, soil, and carbon dioxide. While nature has its own list of plants which depend on other plants, animals, or insects for their food. The article talks about all such nutrition sources.

Key Takeaways - Autotrophs, Photoautotrophs, photosynthesis, heterotrophs, stomata, chlorophyll, algae, parasite, insectivorous plants, saprotrophs, lichens, soil, sun – light, fungi, symbiosis, nitrogen

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Autotrophic Nutrition

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In nature, the mode of nutrition in which organisms make food themselves from simple substances is called autotrophic nutrition. Plants are autotrophs as they prepare their own food. Food is prepared in certain parts of the plants. 

Photosynthesis

Leaves are the ‘kitchen’ of the plant’s body. Plant’s food is prepared in the leaves. All the raw materials are brought to the leaves. The roots absorb the minerals and water present in the soil and transport them upward through the stem to the leaves. They are transported through continuous-pipe like structures known as ‘vessels’. The leaves have tiny pores on their surface which are not visible to the naked eye. These tiny pores known as ‘stomata’ absorb the carbon dioxide in the air. These pores are protected by ‘guard cells’. Leaves have a green pigment called ‘chlorophyll’. The energy from the sunlight is captured with the help of chlorophyll. After having all the raw materials and energy, the synthesis of food takes place in the presence of sunlight thus it is known as photosynthesis (photo-light; synthesis- to combine). Thus the raw materials needed to produce food in plants are sunlight, water, minerals, and carbon dioxide.

With the help of photosynthesis the carbon dioxide and water is converted to oxygen and carbohydrate in the presence of sunlight. This oxygen is released back into the air and the carbohydrate is stored as food. 

Important read – Five Biological Kingdom Classification

Heterotrophic Nutrition

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The mode of nutrition in which organisms take food prepared by plants are called heterotrophic nutrition. Here the heterotrophic plants do not produce food themselves as they do not have chlorophyll. They depend on the ready made food prepared by other plants or insects. 

Parasite

Parasitic plants are those plants which survive on other plant’s food. They cling and grow over their host plants. They do not help their host instead survive on their nutrition. Eg- Cuscuta, Cassytha, etc

The tendrils (string-like) yellowish Cuscuta that is seen in this image is a parasitic plant.

Insectivorous Plants

Insectivorous plants are those plants dependent on insects for nutrition. They are also known as carnivorous plants. They might look green in colour, but they majorly depend on insects for their nutrition. Their leaves have hair-like structure, and they secrete juices which naturally attract the insects towards them. The insects find it difficult to escape the sticky juices after extracting it thus they are trapped in it. The plant slowly closes its leaf or lid over the insect and starts digesting it. Eg. Pitcher plant, Venus fly trap.

Saprotrophs

We can observe a greenish layer or white layer above a rotting piece of bread. If seen closely, you can see tiny sponge – like growth over it. This is known as fungi. Such a type of plant which absorbs its nutrients from dead and decaying matter is called Saprotrophs. Such organisms have a saprotrophic mode of nutrition. Such fungi spread their spores in the air, the spores are microscopic particles which help in reproduction of other fungi. These spores land on moist and warm things where they germinate to let more fungal growth. They use the nutrition of the host things they landed on and spoil them. Eg. Mushrooms

Symbiotic Nutrition

In symbiotic nutrition, the heterotrophic plants share their nutrition and shelter with their host plants. They mutually co-exists. They benefit the host plant and in-return share their nutrients. For example, certain fungi live inside the roots of plants. The plants provide nutrients to the fungus, and, in return, the fungus provides water and certain nutrients. 

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Nutrition from Soil

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Plants absorb minerals and nutrients from the soil. Soil contains nitrogen, potassium, phosphorus, etc. The air also has nitrogen, but the roots of the plants have the potential to absorb the required nitrogen thus they absorb nitrogen from the soil. The potential comes from the bacteria called Rhizobium which can take atmospheric nitrogen and convert it into a usable form. But Rhizobium cannot make its own food. So it often lives in the roots of gram, peas, moong, beans, and other legumes and provides them with nitrogen. In return, the plants provide food and shelter to the bacteria. They, thus, have a symbiotic relationship. 

Important read – Difference between autotrophs and heterotrophs

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Things to Remember

• Apart from leaves plants also produce food in green stems, green branches; we can see this in desert plants which does not have leaves like the one we see in the local plants instead they have spine- or scale – like leaves which reduce the loss of water and carry our photosynthesis.
• The two modes of nutrition in plants are Autotrophic and Heterotrophic.
• Except symbiotic plants all other heterotrophic plants destroy their host or prey.
• At night, when sunlight is absent plants tend to respire like us, by intaking oxygen and releasing carbon-dioxide while in the presence of sunlight they intake carbon-dioxide and release oxygen.
• Chlorophyll, water, minerals, carbon dioxide, and sunlight are the basic requirements of photosynthesis 
• During photosynthesis, the solar energy received from the sun is converted to chemical energy.

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