EFFECT OF PLANT-GROWTH HORMONES ON GROWTH OF AZOSPIRILLUM SP IN MEDIAWITH DIFFERENT CARBON-SOURCES

Studies on the effect of IAA, GA3 and kinetin on the growth of 3 strai ns of Azospirillum have shown that it depended on the strain, the kind of plant growth regulator in the medium, the concentration of a given compound and on the kind of carbon source (malate, succinate or fumar ate). IAA and GA3 in most cases stimulated the growth of azospirilla i n the presence of succinate and fumarate; the same hormones have not e xerted any noticeable effect in media containing malate. Kinetin inhib ited the growth of azospirilla in media with succinate and fumarate. K inetin in the presence of malate weakly stimulated the proliferation o f Azospirillum sp., if applied in low concentrations (0.001-0.01 mug/m l). The same hormone exerted inhibitory effect in malate-containing me dia, when applied in high concentrations (1-10 mug/ml).