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 developa biofertilizer based on filamentous nitrogen-fixing cyanobacteria selected from ricefields and to generate a technological packagecompatible with its use for the rice cropin Iran. Cyanobacteria was isolated and purifiedfrom rice fields in Kalate Naderi. Inthis research we studied the effect of salinity(NaCl, ۰, ۱, ۲ and ۴%) and pH (۵, ۷, ۹ and۱۱) on growth and chlorophyll-a contentsin six species of Anabaena. Results showedthat Anabaena sphaerica Bornet & Flanaultpossessed the best adaptation to pH changes.It could be more active in ۵-۱۱ pH values.A. vaginicola F.E. Fritsh & Rich andA. variabilis Kutzing ex Bornet & Flanaultwere remarkable for salinity tolerance. Theyadapted to salinity stress up to ۲% salt concentrationin the medium. Our results indicatedthat the growth of all strains decreaseby ۴% salt concentration and pH ۱۱. Indeed,Anabaena is a cyanobacterium with nitrogenfixation ability and high potency of adaptationto environmental stress. So, it canbe a useful candidate for biofertilizer in agriculture,particularly in rice fields.

Keywords:

Biofertilizer , Heterocyst cyanobacteria , pH stress , Rice field , Salinity stress