Isoproturon induced changes in peroxidase and catalase enzymes in susceptible and resistant biotypes of Phalaris minor Retz.

Peroxidase and catalase activity was studied in isoproturon susceptible and resistant populations of P. minor with a view to observe differences in innate capacity of different populations under herbicide stress. Resistant populations differed from susceptible populations in exhibiting higher acitivity of these enzymes at the seedling stage. Isoproturon spray caused increase in peroxidase acivity in the susceptible biotypes 5 days after spray. Catalase activity remained low in the sprayed susceptible biotypes. Unsprayed susceptible and resistant biotypes did not differ in isoenzyme pattern of these enzymes. Sprayed resistant plants differ from sprayed susceptible plants in continued presence of isoperoxidases at Rfs 0.32 and 0.36 at 5 days of sampling and at Rfs 0.28, 0.30 and 0.58 at 10 days of sampling.