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Little is known about the agronomic aspects of Mexican Sunflower (Tithonia diversifolia), in spite of its potential for multiple uses. In this study, we evaluated the effects of application rates of biofertilizer and irrigation on yield, growth, and leaf chlorophyll and nutrient content of Mexican Sunflower. In an experiment in the Brazilian semi-arid region, we used a 5 × 2 factorial arrangement, consisting of five application rates of biofertilizer (0, 40, 80, 120, and 160 m3 ha-1), with and without irrigation. The statistical design was randomized blocks with three replications. Irrigated plants of Mexican Sunflower had greater dry and fresh matter yields, greater height, and greater leaf area index and leaf contents of K, Zn, and B. However, the high concentration of bicarbonate in the irrigation water reduced the leaf contents of N, Ca, S, Fe, and Mn. The mean increase in the two cuttings obtained with the use of irrigation was 350% and 314% for fresh and dry matter, respectively. The increase in the biofertilizer application increased the leaf chlorophyll contents of irrigated plants; however, it did not result in production or nutritional gains. In regions with low availability of rainfall, irrigated cultivation of Mexican Sunflower is recommended.

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-Biosolids are residues from the treatment of urban fluids used as a source of nutrients for agricultural and forestry crops. The organic matter contained in this residue and its chemical characteristics may interfere with the behavior of herbicides in the soil. The objective of this study was to evaluate the influence of biosolids on the potential for leaching herbicides mimicking auxin. Two simultaneous experiments were performed: a leaching test of picloram + 2.4-D in soil column with addition of thermally treated biosolids or solarized biosolids and another one to evaluate the effect of leachate application from the leaching tests under inert material. Each type of biosolid was incorporated in sandy soil in the proportions of 0%, 50%, 100% and 150% of the maximum recommended dose for subsurface fertilization for eucalyptus. The soil was conditioned in PVC columns and the herbicide columns based on picloram + 2.4-D (Turuna® Commercial Formulation), corresponding to 240 g L -1 of 2.4-D + 64 g L -1 of picloram at a dose of 3.5 L ha -1 of the commercial product. The columns were submitted to rain simulation and the resulting leachate was collected, followed by its application in sand-filled pots. The Cucumis sativus was sown along the profile of the soil columns and in the pots. The incorporation of the biosolid, independently of the type and dose tested did not interfere in the leaching potential of picloram + 2.4-D. Symptoms of intoxication were observed along all soil columns and pots. Therefore this residue is not very effective for the resolution of environmental problems caused by the leaching of auxin-mimicking herbicides in the soil. Keywords

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A pulverização de herbicidas sobre a rebrota do eucalipto é uma prática comum no setor florestal. Entretanto, observa-se a necessidade de várias operações em uma mesma área para controle das brotações. Objetivou-se avaliar a eficiência dos herbicidas glyphosate e imazapyr, aplicados no fuste principal antes do corte raso das árvores, no controle de brotações de eucalipto. Foram implantados sete tratamentos representados por doses de 3,0; 4,0 e 5,0 mL/fuste de glyphosate (Gli-Up® 360 g i.a L-1) e das doses de 0,3; 0,5 e 0,7 mL/fuste de imazapyr (Chopper Florestal® 250 g i.a. L-1), além de um tratamento-testemunha. A aplicação dos herbicidas foi realizada em inserções feitas nos fustes das árvores. Aos 30 dias após aplicação dos herbicidas, realizou-se o corte das árvores. Aos 150 dias após o corte das árvores, foram realizadas avaliações do número de brotações por cepa, número de cepas com presença de brotações, altura e a eficiência de controle das brotações. A aplicação de glyphosate promoveu redução do vigor das brotações. Porém, observou-se emissão de brotações em pelo menos 80% das cepas avaliadas. A aplicação da dose de 3 mL de glyphosate promoveu porcentagens de 80% de eficiência de controle. Contudo, observou-se que operações de controle adicionais seriam necessárias. A aplicação de imazapyr mostrou-se ineficiente com controle inferior a 25%. Portanto, conclui-se que a aplicação de glyphosate no fuste da árvore em pré-corte reduz o vigor de brotações de eucalipto. Adicionalmente, a aplicação de imazapyr, nas doses e forma de aplicação testadas, não é recomendada para controle de brotações de eucalipto.

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