Rates of paclobutrazol on soil microbial biomass

Abstract

The aim of this work was to evaluate the effect of rates of paclobutrazol on soil microbial biomass, respiration and respiratory quotient (qCO₂). The treatments consisted of six rates of paclobutrazol: 0, 8, 16, 32, 64, and 128 mg a.i. per kg^-1 of a Neossol, corresponding to 0x, 1x, 2x, 4x, 8x and 16x of rate recommended for application in field. The soil samples were incubated during 60 days and evaluations of soil microbial biomass, CO₂ release and qCO₂ were done at 1, 7, 15, 30 and 60 days. Initially, there was a decrease in soil microbial biomass content after application of paclobutrazol that increased after 15 days. The compound increased soil respiration until 30 days. The qCO₂ increased in the treatments with higher rates than 16 mg a.i. per kg^-1 of soil. Application of paclobutrazol caused an initial decreasing on soil microbial biomass.