Ação de herbicidas sobre cultivares de cana-de-açúcar e na atividade da microbiota do solo

• Ano de defesa: 2010
• Autor(a) principal: Silva, Alexandre Ferreira da
• Orientador(a): Ferreira, Francisco Affonso
• Banca de defesa: Aspiazú, Ignácio , Sediyama, Tocio
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitotecnia
• Departamento: Plantas daninhas, Alelopatia, Herbicidas e Resíduos; Fisiologia de culturas; Manejo pós-colheita de
• País: BR
• Palavras-chave em Português: Saccaharum spp; Herbicida; Seletividade; Biomassa microbiana; Coeficiente respiratório
• Palavras-chave em Inglês: Saccaharum spp; Herbicide; Seletividade; Microbial biomass; Respiratory coefficient
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1133

The selection of herbicides applied in a certain crop requires knowledge not only about the efficiency of these products in the weed control, but also their effect on cultivars of this species and the impact of such herbicides on the soil microbiota activity. The present work aimed to seek such information and quantify the effects of the eight herbicides most widely employed in sugarcane on four cultivars of this crop. The experiment was carried out in a randomized block design, with three replications. Evaluations were made of the effects of the herbicides clomazone, tembotrione, tebuthiuron, diuron, trifloxysulfuron-sodium, sulfentrazone, hexazinone and MSMA on sugarcane cultivars RB925345, RB855156, RB867515 and SP80-1816. Eighty days after planting of the crop (45 days after the application of the herbicides), height, stem diameter, number of tillers and leaves, leaf area, specific leaf area, leaf dry matter, stalk and total crop plants were determined. Then, evaluations were also carried out of the impact of these herbicides on microbiota breathing activity, microbial biomass carbon, metabolic quotient of rhizosphere microorganisms and acid phosphomoesterase activity. The intoxication of the sugar cane cultivars by herbicides was monitored during the evaluation. All variables analyzed were affected by the treatments. Different levels of tolerance to herbicides were observed for the sugar cane cultivars, and RB867515 was considered the most tolerant. The mixture of diuron + hexazinone caused the highest reduction of dry matter in all the cultivars, in comparison to the other herbicides. Most herbicides tested caused high levels of toxicity symptoms in the sugar cane cultivars, except tembotrione and tebuthiuron. The herbicides trifloxysulfurom-sodium and diuron + hexazinone led to the most stressful conditions for the sugar cane rhizosphere microbiota. The rhizosphere microbiota activity of the cultivar SP80-1816 was the most affected. Herbicide effects were not observed on the acid phosphomonoesterase activities in the cultivars. It was concluded that sugarcane cultivars and soil microbiota associate to those present different tolerance to the different herbicides tested.