Evolução de CO2 e atividades enzimáticas em amostras de solo tratado com herbicidas

Abstract

-Effects of bentazon, metolachlor, trifluralin, imazethapyr, imazethapyr+lactofen, haloxyfop-methyl, glyphosate and chlorimuron-ethyl at rates of 2 and 10 times the equivalent commercial dose on soil microbial activity was evaluated in soil samples extracted from a field never treated before. Global soil microbe respiration, estimated by CO 2 production at 2, 4, 8, 12, 16, 20, 24 and 28 days of soil incubation and enzymatic activities (dehydrogenase and fluorescein diacetate hydrolysis) at 8 and 28 days were used as bioindicators. Bentazon and mixture imazethapyr+lactofen at the highest rate and haloxyfop-methyl at both rates, inhibited soil respiration although with differences in timing and duration. None of the herbicides affected FDA hydrolysis. Dehydrogenase activity was inhibited at 8 days of incubation with bentazon and imazethapyr at high rates but it was stimulated by metolachlor and imazethapyr at low rate and glyphosate at the highest rate. Herbicide effects on soil microbial activity was detected with higher sensitivity by global soil microbe respiration and dehydrogenase activity than by FDA hydrolysis. Only dehydrogenase activity and soil respiration estimations at 8 days of soil incubation had significant correlation. Results indicated the need of multiple estimations when evaluating herbicides effects on soil microbiota

Rhizospheric activity of phytoremediation species in soil contaminated with picloram1

“…The picloran application does not affect the biological quality of the soils studied. Rhizospheric regions are characterized by an intense microbiological activity, and can support the growth of microbial populations up to 100 times higher than in non-rhizospheric regions (Moreira & Siqueira 2002, Fernandez et al 2009). Besides that, the root exudates of plants determine the microbial composition of the rhizosphere, varying according to the plant species and age (Costa et al 2000), as well as other factors such as plant exposure to toxic compounds and soil type (Fernandez et al 2009, White & Newman 2011.…”

“…These plants can accelerate the picloram microbiological degradation. In addition, they can also extract this herbicide from the soil and accumulate it in roots and leaves (Santos et al 2007, Fernandez et al 2009). The evaluation of the microbial activity in the rhizosphere is a tool used to infer the role of the microbiota in herbicide remediation.…”

Aspectos do glufosinato de amônio como principal ferramenta de controle no manejo de plantas daninhas na soja

“…Na avaliação de colonização micorrízica arbuscular (Tabela 4) foi observado menor colonização nas plantas de soja pela aplicação do glufosinato de amônio em soja tolerante a esse herbicida em comparação com todos os outros tratamentos. (Zablotowicz e Reddy, 2004;Fernandez et al, 2009).…”