Growth and nitrogen fixation of azolla

Abstract

Among the six azolla cultures studied A. microphylla (Galapagos Islands) and Azolla sp. (Brazil) have recorded maximum growth rate. The highest nitrogenase activity was recorded in A. filiculoides (Italy) followed by Azolla sp. (Brazil). Nitrogen content was also more in these two spacies of Azolla. The chlorophyll 'a'accumulation was significantly more in Azolla sp. (Brazil) whereas chlorophyll 'b'was more in Azolla sp. (Paraguay). Azolla sp. (Brazil) has also registered higher GS, GDH and GOGAT activities followed by Azolla sp. (Paraguay) Ammonia excretion was found to be maximum on 15th day after inoculation in A. mexicana (California) followed by A. microphylla (Galapagos islands). The micronutrients status of Mn, Cu, Fe and Zn was investigated and iron content was significantly more in all the azolla cultures. Iron content was maximum in A. pinnata (Coimbatore) while A. mexicana (California) has recorded higher Mn content. A. filiculoidas (Italy) has recorded higher Cu and Zn contents. In general, it was noticed that the accumulation of Cu, Fe and Zn was relatively more in A. filiculoides (Italy) compared to other cultures.