ABSTRACT
Nitrogen (N) is a microelement found in the environment in inorganic form. It is then converted into organic components like amino acids by the nitrogen assimilation process. Nitrogen is an important component of most of the biomolecules like nucleic acids, proteins, and vitamins. Dinitrogen (N2) has to be further processed in order to convert it into a biologically functional variety. Nitrogen is gained by the plant through nitrate or ammonium. Nitrates remain a major source of nitrogen for all plants because of their versatile functions in both plant nutrition and physiological regulations. The nitrate assimilation pathway initiates with the uptake of nitrate followed by nitrate reduction producing ammonium, which is then fixed into the amino acids, glutamine, and glutamate in most plants. This chapter elaborates on nitrate assimilation and regulation. The link between nitrate and nitric oxide is also discussed, along with nitrogen carbon interactions, Nitrogen use efficiency (NUE) and nitrate pollution will also be discussed.
