Effect of growth-promoting chemicals on growth, nitrogen fixation and heterocyst frequency of a blue-green alga.

IAA was found to stimulate growth, nitrogen fixation and pigment synthesis in Anabaena doliolum in all concentrations tested. Heterocyst frequency was stimulated up to a concentration of 50 ppm IAA. NAA stimulated growth and nitrogen fixation up to 10 ppm. GA promoted growth, pigment synthesis, heterocyst frequency and nitrogen fixation only up to a concentration of 2 ppm. Kinetin promoted growth up to 100 ppm and synthesis of pigments, while nitrogen fixation was stimulated up to 5 ppm.