Impact of graded concentration of NaCl on the growth and heterocyst Frequency of parent and mutant strain of Anabaena variabilis RDU-1

Cyanobacteria Anabaena variabilis as biofertilizer for rice cultivation has a beneficial effect on crop productivity and maintenance of soil fertility. In the present study, the parent and multiple herbicide resistent mutents of Anabaena variabilis , RDU-1 strains were taken for examining their relative response to salt stress under diazotrophic growth conditions. Mutant strains differentiated heterocyst with more or less similar frequency in all the concentration of NaCl ranging from 20 mM to 100 mM in comparision to parent strain decreased even in 20 mM to NaCl. Heterocyst differentiation is salt tolerant in the mutant strain and salt sensitive in parent strain.