Review: Physiological Studies on Leguminous Filed Crops

Although man and other land animals live in an ocean of air with 79% nitrogen, its supply through food depends on the availability of nitrogen fixed from atmosphere and incorporated into chemical compounds. The process of incorporating atmospheric nitrogen into various simple and complex nitrogenous compounds in the plant is known as biological nitrogen fixation. Only prokaryotic microorganisms which include bacteria and blue green algae are capable of fixing nitrogen from the air into organic molecules in the plant. They perform this job either independently or in association with higher plants. The former is called as non-symbiotic while later symbiotic nitrogen fixation.