Abstract
The differential response of cyanobacteria, collected from the rice field soils of Sambalpur district of Orissa to an organophosphate pesticide, Rogor (dimethoate 30 EC) was examined. Four different cyanobacterial strains viz. Anabaena variabilis, Nostoc muscorum, Calothrix parietina and Westiellopsis prolifica were selected for the study. They showed their relative tolerance to the test pesticide, Rogor in laboratory culture, so far their growth, chlorophyll-a content, carotenoid, protein and extra-cellular amino acids are concerned. Of the test organisms, Calothrix parietina was comparatively more tolerant, while Anabaena variabilis was more sensitive to Rogor. However, Nostoc muscorum that does not possess thick slime layer tolerated relatively higher pesticide doses. A pesticide concentration dependent reduction in chlorophyll-a content, carotenoid, protein and extra-cellular amino acids of the organisms was observed.