Effect of the herbicide prometryn on the metabolic activity of the cyanobacterium nostoc muscorum

The action of prometryn [1-6 ppm] was studied on nitrogen, carbon, nucleic acids, total amino acids contents as well as nitrate reductase enzyme acticvity of Nostoc muscorum Ag. Total nitrogen, total amino acids, total soluble sugars, DNA and RNA as well as nitrate reductase activity increased with increasing of prometryn concentrations until reached maxima at 3ppm, any increase above it was inhibitory. At 1 ppm, polysaccharides and total carbohydrates contents reached 5.94 and 8.28%, respectively: more than its respective control, while the concentrations above 1 ppm were inhibitory. The amino acids cysteine and alanine disappeared at all prometryn concentrations, while they were detected in control [untreated dry matter]