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.