What enables leguminous plants to fix nitrogen?

Hint: Leguminous plants are the plants which produce legumes such as rice, pea, gram etc. Nitrogen fixation is a chemical process in which atmospheric nitrogen is assimilated into organic compounds especially by certain microorganisms as a part of the Nitrogen cycle. Nitrogen is very important for plants to make chlorophyll. It is also a very important component for plants to make proteins and amino acids. This nitrogen cannot be used directly by plants.

Complete Explanation:
As we all know, there is \[78\% \] of nitrogen present in the atmosphere. But plants cannot directly use this nitrogen as they use carbon dioxide. They require nitrogen in soluble form. The bacterium called Rhizobium helps them in the process. The bacterium rhizobium lives in the root nodules of leguminous plants such as pea with which it has a symbiotic relationship which is involved in the fixation of nitrogen in these plants. Rhizobium takes nitrogen from the soil and converts it into soluble nitrates. The nitrates then can be used by plants for their growth and development. These bacteria live in the root nodules of leguminous plants such as gram, beans, peas and other legumes and provide them with nitrogen. Plants in return provide food and shelter to the bacteria.

Note:
Plants cannot fix nitrogen because it is unavailable to plants and is in gaseous form. So, plants cannot use it directly without undergoing a transformation. Nitrogen is important to all living things, including humans. Deficiency of nitrogen in plants is known as chlorosis. This deficiency can show up in plants as yellow colouring of leaves in plants.