Azolla : a potential bio-resource for agriculture and allied activities

Azolla is a floating aquatic fern and is commonly called as mosquito fern, duckweed fern, fairy moss and water fern. Azolla species are distributed throughout the world in temperate and tropical fresh waters. Azolla floats on the surface of water with the help of numerous small, closely overlapping scale-like leaves, with their roots hanging through the water and forms large mats. The habitats include ponds, ditches, canals and paddy fields. It is also commonly seen in places where agricultural runoff or urban effluent accumulation is seen3 (Raja, 2014). By nature, they form a symbiotic relationship with the cyanobacterium Anabaenaazollae, which fixes atmospheric nitrogen, giving the plant access to the essential nutrient that helps to colonize areas of freshwater and grow at great speed. Azolla grow best at temperature range of 25-30 degrees C.The favourable water temperature for multiplication of Azolla is between 18-26 degrees C. The ideal characteristics that make Azolla significant to agriculture and allied activities are its rapid growth rate and possession of various nutrients particularly protein. The relative growth rate of Azolla is high as it generally doubles its weight in 2-4 days period resulting in very high biomass in a short period of time.