An Overview of Azolla in Rice Production: A Review

Azolla is a free-floating water fern which in symbiotic association with cyanobacterium Anabaena azollaefixes the atmospheric nitrogen. Nitrogen fixing ability of cyanobacterialsymbiont varies between 30 and 60 kg N ha−1 which designates Azolla as an important biological nitrogen source for rice ecosystem. Inoculation of Azolla is an alternative and sustainable source of nitrogen to increase the rice productivity and it also can decrease the use of synthetic fertilizer. A number of past researches prove that Azolla has been used as apotential biofertilizer for rice production. Azolla is either incorporated in the soil before rice transplanting or grown as a dual crop along with rice. The objective of this paper is to provide a brief account of importance as well as developments in the utilization of Azolla-Anabaena system in agriculture, mainly rice production.