A study was conducted on two BGA isolates, Cylindrospermum majus and Nostoc muscorum of Assam North-East India. For which their growth behavior, nutrient requirement and biomass production through out the year and seasonal influence on them were thoroughly studied. The parameters mostly included biomass productivity, chlorophyll-a and total chlorophyll content, total N-content, packed cell volume (PCV), indole-acetic acid (IAA) production and seasonal growth. Out of the two, Nostoc muscorum was the better strain in terms of biomass (0.128mg/100ml), total chlorophyll content (0.42mg/ml), total N content (2.62%), PCV (1.57 ml pellet ml-1), IAA content (4 ppm) and as a result of composite culture of two BGA isolates in field condition, non sterile soil was identified as most suitable combination when taken as substrate. Both the strain showed their best growth during the summer season.
