Impact of Salinity and pH on Several Species of Anabaena (Nostocaceae, Nostocales) Isolated from Rice Fields in Iran

The purpose of this study is to develop a biofertilizer based on filamentous nitrogen- fixing cyanobacteria selected from rice fields and to generate a technological package compatible with its use for the rice crop in Iran. Cyanobacteria was isolated and purified from rice fields in Kalate Naderi. In this research we studied the effect of salinity (NaCl, 0, 1, 2 and 4%) and pH (5, 7, 9 and 11) on growth and chlorophyll-a contents in six species of Anabaena. Results showed that Anabaena sphaerica Bornet & Flanault possessed the best adaptation to pH changes. It could be more active in 5-11 pH values. A. vaginicola F.E. Fritsh & Rich and A. variabilis Kutzing ex Bornet & Flanault were remarkable for salinity tolerance. They adapted to salinity stress up to 2% salt concentration in the medium. Our results indicated that the growth of all strains decrease by 4% salt concentration and pH 11. Indeed, Anabaena is a cyanobacterium with nitrogen fixation ability and high potency of adaptation to environmental stress. So, it can be a useful candidate for biofertilizer in agriculture, particularly in rice fields.