BABITA SAINI, SUN1TA SUNEJA KAMLESH KUKREJA AND SNEH GOYAL
Abstract
A long term experiment on commonly used herbicides in rice-wheat rotation system had been conducted-at Regional Research Station, Karnal. Wheat rhizosphere soil samples of above experiment were collected before and after the application of herbicide during the rabi season of 2005-06 and were analyzed for basal respiration, soil dehydrogenase and alkaline phosphatase activity. Basal respiration as indicated by CO2 evolved was slightly more in herbicide treated plots as compared to weedy and weed free control under both green manuring ( GM) and without green manuring ( WGM ) conditions. Later on, with the progress of time after the application of herbicide, small differences were observed in the basal respiration of different treatments. Soil dehydrogenase activity was slightly higher in herbicide treated plots than weedy control under GM conditions at 30 and 60 days after treatment ( DAT ) while in WGM conditions, activity was significantly less in herbicide treated plots than weedy control. Alkaline phosphatase activity was inhibited by herbicide application at 15 & 30 DAT in GM conditions while in WGM conditions, inhibitory effect was not observed rather enzyme activity of permanent herbicide treated plot was higher than weedy control. Later on, small differences in enzyme activity of different treatments were observed.