Assessment of the effects of the photosynthesis-inhibiting herbicides Diuron, DCMU, metamitron and metribuzin on growth and nitrogenase activity ofNostoc muscorumand a new cyanobacterial isolate, strain G4

摘要

The influence of the photosynthesis-inhibiting herbicides Diuron, DCMU, metamitron, and metribuzin on growth and nitrogenase activity ofNostoc muscorumand a new cyanobacterial isolate, strain G4, was studied. The experiments were performed under N2-fixing photoautotrophic conditions. Both cyanobacteria showed a high degree of tolerance towards the herbicides tested. In the presence of metamitron (35, 70, and 140 ppm) and metribuzin (7, 14, 35, and 70 ppm) strain G4 proliferated as well as the control culture. Metamitron and metribuzin had no influence on the nitrogenase synthesis of strain G4 andN. muscorum. When treated with 1 μMDCMU, strain G4 andN. muscorumshowed partial inhibition for the first few days, but entirely recovered during succeeding incubation. In the presence of 10 ppm Diuron,N. muscorumand strain G4, compared to the control, showed 30 and 80 nitrogenase activity, respectively