The impact of nitrogen-fixing blue-green algal (BGA) strains, namely
Anabaena variabilis, Aulosira fertilissima, Nostoc muscorum
, was studied at different levels of nitrogen fertilizer on specific soil parameters such as microbial populations, pH, EC, redox potential, chlorophyll, dehydrogenase and nitrogenase activity under a rice crop. The inoculation of the soil with BGA strains resulted in higher microbial populations (BGA, bacteria, fungi and actinomycetes) and had a significant influence on redox potential. A significant increase in soil chlorophyll, dehydrogenase and nitrogenase activity was observed during crop growth due to BGA application.
A set of thirty
strains, isolated from diverse geographical regions of India, were characterised using morphological and physiological attributes. Significant differences were observed among the
strains with regard to the shape and size of trichomes and individual cells within a filament, besides the activities of the enzymes involved in nitrogen metabolism. Informative morphological and physiochemical characters have been identified that could aid in differentiation and utilisation of
strains as bioinoculants or as sources of pigments.