In the present study a spectrophotometric method for Cr(VI) determination in organic fertilizers, especially those from tanning industry residues, is proposed. Conditions for chromium extraction, extract clean-up and analytical characteristics of the method were established. The method is based on the complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) in acid medium (pH 2.0). A mixture of NaOH and Na2CO3 solution at 0.125 and 0.07 mol L–1 (pH 12), respectively, and heating at 90 °C for 60 min were the best conditions for chromium extraction. Florisil and activated charcoal were tested for clean-up of the extract, with activated charcoal being effective. Under the established conditions, the calibration linear range is up to 2500 μg L–1 Cr(VI), the results obtained are in agreement with the value of a certified reference material (CRM041), precision is better than 5% for five consecutive determinations of a solution at 1000 μg L–1 of Cr(VI) and the limit of quantification is 1.62 μg g–1. In can be concluded that the method is robust, accurate and precise, and can be easily applied for the determination of Cr(VI) in routine analysis, since it complies with legislation of most countries regarding the maximum allowed concentration of 2 μg g–1 of Cr(VI). CrVI Cr VI Cr(VI fertilizers residues proposed extraction cleanup clean 1,5diphenylcarbazide 15diphenylcarbazide diphenylcarbazide 1,5 1 5 DPC (DPC pH 2.0. 20 2.0 . 0 2.0) NaCO Na CO Na2CO 0125 125 0.12 007 07 0.0 L1 L L– 12, 12 , 12) respectively 9 C 6 effective 250 CrVI, CRM041, CRM041 CRM (CRM041) 100 162 62 1.6 g1 g robust precise analysis g– CrVI. 5diphenylcarbazide 15 1, 2. 012 0.1 00 0. 25 CRM04 (CRM041 10 16 1. 01 CRM0 (CRM04 (CRM0 (CRM

RESUMO: A homeostase nutricional mineral em resposta a diferentes concentrações de Hg (0, 25 e 50μM) foram avaliadas em plantas de Pfaffia glomerata. A exposição ao mais alto nível de Hg (50µM) causou um decréscimo de 15,5% e 20%, respectivamente, na matéria fresca da parte aérea e raízes. As concentrações de Hg na parte aérea e raízes aumentaram linearmente com o aumento das concentrações de Hg. A concentração de Ca decresceu na parte aérea somente em 50µM Hg, enquanto as concentrações de K e Mg na parte aérea decresceram tanto em 25 como em 50µM Hg, quando comparado ao controle. Observou-se um significativo decréscimo nas concentrações de Cu, Zn, Fe e Mn nas plantas expostas ao Hg, mas principalmente Zn, Mn e Cu nas raízes. Por outro lado, a concentração de P aumentou em raízes e parte aérea de plantas expostas a 25 e 50µM Hg, enquanto a concentração de Na aumentou somente nas raízes em 25 e 50µM Hg. No geral, as concentrações de nutrientes nos tecidos de P. glomerata expostas ao Hg foram significativamente diminuídas, o que indica que o Hg pode causar alterações na homeostase nutricional mineral dessa espécie.

ABSTRACT: The mineral nutritional homeostasis in response to different concentrations of Hg (0, 25 and 50μM) was evaluated in Pfaffia glomerata plant. The exposure to the highest level of Hg (50µM) caused a decreasing in shoot and root fresh weights of 15.5% and 20%, respectively. Both shoot and root Hg concentrations increased linearly with increasing external Hg concentrations. Ca concentration decreased in shoot only at 50µM Hg, whereas shoot K and Mg concentrations decreased at both 25 and 50µM Hg, when compared to the control. A significant decrease in Cu, Zn, Fe and Mn concentrations in plants exposed to Hg was observed, but most Zn, Mn, and Cu in the roots. On the other hand, P concentration increased in both root and shoot of plants exposed at 25 and 50µM Hg, whereas Na concentration increased only in the root at 25 and 50µM Hg exposure. In general, tissue nutrient concentrations in P. glomerata plantlets exposed to Hg were significantly decreased, which indicates that the Hg may cause alteration on the mineral nutritional homeostasis of this species.

Na safra agrícola de 2007 foi instalado um experimento com a cultura do trigo com o objetivo de avaliar a influência do zinco, manganês e molibdênio aplicados juntamente com fungicidas sobre a severidade de doenças e duração da área foliar verde. As aplicações dos fungicidas foram realizadas no final do emborrachamento e no florescimento, e a de micronutrientes, somente no florescimento. Foram analisados os teores de micronutrientes nas folhas, severidade das doenças causadas por Drechslera tritici-repentis eSeptoria tritici, índice SPAD (Soil Plant Analysis Development), peso hectolítrico, peso de mil grãos, tamanho de espigas, e rendimento de grãos. O uso do epoxiconazol + piraclostrobina proporcionou o melhor controle de D. tritici-repentis e de S. tritici. Produtos com epoxiconazol e piraclostrobina atuaram na fisiologia da planta, incrementando os teores de micronutrientes nos tecidos e prolongando o tempo que o trigo permaneceu com área foliar fotossinteticamente ativa. Epoxiconazol + piraclostrobina, piraclostrobina e epoxiconazol pulverizados associados ou não a micronutrientes, propiciaram aumento do peso hectolítrico, peso de mil grãos e rendimento, quando comparados à testemunha.

In the crop cycle of 2007, an experiment was carried out in order to evaluate the influence of zinc, manganese and molybdenum sprayed together with fungicides on the severity of diseases and leaf area maintenance in wheat. Fungicides were sprayed at the end of booting and during flowering, whereas micronutrients were only sprayed during flowering. Micronutrients levels in the leaves, severity of diseases caused by Drechslera tritici and Septoria tritici, SPAD (Soil Plant Analysis Development) index, hectoliter weight, thousand-grain weight, ear size, and grain yield were evaluated. The use of epoxiconazol + pyraclostrobin led to a better control of Drechslera tritici and Septoria tritici. Products containing epoxiconazol + pyraclostrobin had an effect on plant physiology by increasing the levels of micronutrients in tissues and prolonging the time during which wheat remained with photosynthetically active leaf area. Epoxiconazol + pyraclostrobin, pyraclostrobin and epoxiconazol sprayed in association or not with micronutrients, led to increased hectoliter weight, thousand-grain weight and grain yield relative to control.