Effect of paclobutrazol on microbial biomass, respiration and cellulose decomposition in soil

Paclobutrazol is a plant growth regulator largely utilized in mango cultivation and usually applied directly to soil. The aim of this study was to examine the effect of paclobutrazol on soil microbial biomass, soil respiration and cellulose decomposition in Brazilian soils under laboratory conditions. Soil samples were collected from fields with and without a reported history of paclobutrazol application. A solution of paclobutrazol (8 rng of active ingredient kg(-1) of soil) was added to soils, which were then incubated at 28 degrees C for 30 days. Paclobutrazol decreased soil microbial biomass, soil respiration and cellulose decomposition in soil with and without a report of paclobutrazol application, while significant increase was observed in the respiratory quotient (qCO(2)). Our results show that the soil microbiological attributes were negatively affected by paclobutrazol in short-term experiment. (C) 2009 Elsevier Masson SAS. All rights reserved.