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cellular structures and organelles. It also helps regulate metabolic reactions by taking part in
the structure of enzymes.
Chlorophyll Synthesis: Chlorophyll is the green pigment found in chloroplasts, the cell
organelles in plants where photosynthesis takes place. Photosynthesis is an important process
in which plants use solar energy to convert carbon dioxide and water into glucose and oxygen.
Chlorophyll contains nitrogen in its structure and therefore plants need nitrogen for
photosynthesis.
Formation of Nucleic Acids: Nitrogen is found in the building blocks of nucleic acids (DNA
and RNA) in plants. Nucleic acids store the hereditary information of plants and are vital for
the synthesis and transmission of genetic material.
Formation of Amino Acids: Nitrogen is the building block of amino acids in plants. Amino
acids are the basic building blocks for protein synthesis and are critical for the growth and
development of plants.
Plant Growth and Productivity: Nitrogen supports the development and growth of root, leaf,
and stem tissues of plants.
16.1.1. Deficiency and excess of nitrogen
Nitrogen deficiency is mostly seen in young leaves. Leaves develop light green color, in case
of further progression, leaves turn yellow, and a lack of photosynthesis is observed. Chlorosis
(yellowing) is first seen in old leaves and then in young leaves. Cell size and cell division
decrease and plants become stunted. In excess nitrogen, premature aging of leaves is observed.
16.2. Phosphorus
Phosphorus is an essential nutrient element that is vital for plants. Plants need phosphorus for
growth, energy transfer, cell structure, and formation of genetic materials [96]. The main
functions of phosphorus in plants are as follows:
Energy Transfer: In plants, energy transfer takes place inside the cell through ATP (adenosine
triphosphate) molecules. Phosphorus is one of the basic components of ATP molecules and
plants need phosphorus where energy is required for their cellular activities and biochemical
reactions.
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