Ecology, Environment and Conservation Paper

INFLUENCE OF PESTICIDES ON DEHYDROGENASE ACTIVITY IN GROUNDNUT (ARACHIS HYPOGEA L.) SOILS

M. Madakka, Pradeep Kumar Sake and V. Rangaswamy

Abstract

The influence of four pesticides viz., profenofos, deltamethrin, thiram and difeneconazole and two insecticide combinations viz., profenofos+cypermethrin, deltamethrin+endosulfan at 0.0,1.0,2.5,5.0,7.5 and 10.0 kg/ha were assessed for their efffects on the activity of dehydrogenase was quantified in terms of triphenyl formazen accumulation from triphenyl tetrazolium chloride in two agricultural soils collected from a fallow groundnut fields of Anantapur district. The effects of selected pesticides on dehydrogenase activity was dose dependent. This enzyme activity increased with increasing concentrations of the pesticides upto 5.0 kg/ha. Higher rates of (7.5, 10.0 kg/ha) of these pesticides were either toxic or innocuous to the dehydrogenase activity. The significant stimulation in the activity of dehydrogenase associated with 2.5 kg/ha of pesticides in black soil, where as in red soil it was 2.5 kg/ha of profenofos, deltamethrin, thiram and 5.0 kg/ha difeneconozole. In case of insecticide combinations the significant stimulation of dehydrogenase activity was observed 2.5 kg/ha of profenofos+cypermethrin, 1.0 kg/ha of deltamethrin+endosulfan in black soil, where as in red soil it was observed at 1.0 kg/ha of profenofos+cypermethrin, deltamethrin+endosulfan. Further incubation the activity of dehydrogenase was significantly more at 21 day and enzyme activity decreased progressively with increasing period of incubation.