Abstract

                                The survey on Azolla diversity revealed that Azolla pinnata and Azolla microphylla are the two species found throughout the agro-climatic zones of Tamil Nadu.The pot-culture experiments to screen the strains for local adaptability for the Tiruvallur district revealed that during cold months (Nov-Dec), most of the species grow with high growth rate (5 to 7 days doubling time) and during Jan-Feb, the doubling time increased from 7.5 to 9.5 days.Among the different Azolla species studied, A. pinnata and A. microphylla recorded a high growth rates and higher biomass production at elevated temperatures. Selected Azolla strains were highly suitable to grow well under open field conditions.Azolla pinnata and Azolla microphylla strains suitable for high-temperature zone district of Tamil Nadu (Tiruvallur) were identified. These strains can withstand the temperature up to 37°C in the months of July – Aug and produce high biomass and application of Azolla microphylla (Dual crop) with a 75 per cent recommended dose of NPK recorded as the maximum grain and straw yield of rice followed by the Azolla pinnata(dual crop) with 75 per cent recommended dose of NPK. These Azolla strains could be used as animal feed and also as green manure

Key words : Rice; Azolla pinnata;Azolla microphylla;Biomas; Growth; Yield