Azospirillum Bioinoculant Technology: Past To Current Knowledge And Future Prospects

Abstract

Azospirillum is a curve-shaped vibroid Gram-negative, measuring about 1–1.5 µm in diameter, motile because of possessing Peritrichous flagella that are capable of fixing atmospheric nitrogen under microaerophilic conditions 52in association with the roots of cereals. Azospirillum was well known for many years as PGPR because it was isolated from the rhizosphere region of many grasses and cereals universally in tropical as well as in temperate climates. Azospirillum is considered as the most valuable bioinoculant in the group of plant growth-promoting rhizobacteria (PGPR) because it is not only the microorganism capable of colonizing the roots of agricultural crops, along with root colonization Azospirillum sp. have the tendency of producing more beneficial compounds which are highly beneficial to crops. Azospirillum biofertilizers have a history going back to the beginning of the 20th century. However, researchers still must find innovative and novel strains and improve production strategies and methods of application and mode of action. Azospirillum is one of the widely used biofertilizers in organic farming. Azospirillum sp. contribute to increased yields of cereal and grasses by improving root development in properly colonized roots, increasing the rate of water and mineral uptake from the soil, and by biological nitrogen fixation. A better understanding of the basic biology of the Azospirillum microbe and plant root interaction may lead to greater efficacy in its application as an effective biological nitrogen-fixing biofertilizer. The products containing Azospirillum strains and their use begin to play an important role in recent agriculture and as an alternative to expensive chemical fertilizers and sometimes not environmentally friendly products. This chapter analyzes the genus Azospirillum, taxonomy, occurrence, distribution, characters, interactions, nitrogen fixation, growth hormones, siderophore production, and nutrient uptake.