Herbicides effect on microbial activity of soil cultivated with different genotypes sugarcane

Abstract

We aimed with this work to evaluate the effects of herbicides on microbial activity of soils planted with sugarcane.  The experiment was installed in a randomized blocks design in a factorial scheme 5 x 4 with four replications. Factor A was composed by sugarcane genotypes (RB72454, RB835486, RB855113, RB867515 and RB947520) and B corresponded to the herbicides (ametryn, trifloxysulfuron-sodium and the formulated mixture ametryn + trifloxysulfuron-sodium), and a no herbicide control. At 15 and 45 days after herbicide application (DAT), the rhizospheric soil was collected for determination of the basal respiration (C-CO₂), microbial biomass carbon (MBC) and the metabolic quotient (qCO₂). Herbicide effects on soil microbiote varied with sugarcane genotype. RB835486 was the one which most affected MBC mainly at 45 DAT, and qCO₂ was most affected by RB72454. For herbicides, especially trifloxysulfuron-sodium, there was change in MBC as herbicide dose increased for most genotypes, which also promoted reduction on qCO₂ proving this herbicide to be the one with greatest impact on micro-biological indicators of soils. The herbicides ametryn and mixture ametryn + trifloxysulfuron-sodium negatively affect the C-CO₂, and the CBM qCO₂, in particular when applied on the genotype RB72454.