Influence of boscalid on the activities of soil enzymes and soil respiration

• Boscalid significantly inhibits the activity of soil phosphatase and β-d-glucosidase.
• Boscalid has certain extended positive effects on soil phenol oxidase and peroxidase.
• Boscalid has a negative effect on soil respiration.
• A new fluorimetric microplate assay was used to determine the enzymes activities.

Using fluorimetric microplate enzyme assay, the effects of a novel fungicide, boscalid, on the activities of the four soil enzymes related directly to the C-cycling and P-cycling were investigated thoroughly over a period of 60 days. The results suggested that 10–200 mg kg−1 boscalid significantly inhibited phosphatase activity during the whole course of incubation. Apart from stimulating obviously within the first 7 days treatment, β-d-glucosidase activity was also inhibited dramatically from 35 to 60th day of incubation. Moreover, boscalid at 100 and 200 mg kg−1 exhibited inhibitory effect on the activities of phenol oxidase and peroxidase on 7th day, while posed a stimulating or no obvious negative effects on them in the latter incubation time. Among the four enzymes, phosphatase was most sensitive to boscalid, and its lowest activity was 48.3% of the control. Boscalid ranged from 10 to 100 mg kg−1 also inhibited soil respiration at all the experiment time. All the results indicated that the main effects of boscalid on soil phosphatase, β-d-glucosidase and respiration were negative, yet a certain positive effect on soil phenol oxidase and peroxidase in a long term.

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