1000 resultados para relação N:S foliar


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Aiming to evaluate the dose and application schedule of foliar Zn-sulfate spraying in growing and yield of Arabic coffee Mundo Novo, a field experiment was set up on Distroferric Red Latosol, at the Experimental Station of the EPAMIG in São Sebastião do Paraíso. The statistical design used was randomized blocks in s 4 x 2 factorial scheme with five replications and a 30-plant plot with six central valid or four applications per agricultural year. Phosphorus and zinc leaf levels were evaluated for eight years and the yields. It was possible to conclude that there is a positive response to the in the leaves. Four low concentrations sprayings promoted higher yields than two high concentrations. The highest yields were achieved with 10.8 and 12.6 kg ha-1 of ZnSO4 and 4 yearly applications, respectively. It is suggested as a critical range for the Zn leaves values between 10 and 28 mg kg-1 and for P/Zn ratio, between 100 and 150. ) was sprayed under 4 concentrations 0; 0.5; 1.0 and 1.5%, two applied on the leaves in terms of yield, and to Zn levels

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Forestry has grown in a continuous and accelerated manner in Brazil, constituting a strategic activity for the generation of employment, income and tributes, favoring social and economic development of Brazilian agribusiness. The objectives of this study were: (1) evaluate the contents of K, Ca and Mg in the reserve compartments, non-interchangeable, interchangeable, available and the speed of its release, its correlations and its effects over productivity (annual average increment – AAI) of eucalyptus plantations, in forest sites cultivated in soils of the state of Rio Grande do Sul; (2) evaluate the initial growth, nutrition and physiological aspects of eucalyptus plants, cultivated with and without the addition of mineral sources of potassium (K), calcium (Ca) and magnesium (MG), in soils obtained from forest sites in the state of Rio Grande do Sul. In the first study, contents of K, Ca and Mg were evaluated in sulfuric digestion extract, boiling nitric acid, ammonium chloride, Mehlich-1 (only K), potassium chloride (Ca and Mg), as well as the release speed of these nutrients in the soil. In the second study, growth variables, nutritional aspects, photosynthetic rate (A) and transpiration rate of the plants (E) grown in distinct soils were evaluated under controlled conditions. The contents of K, Ca and Mg varied between compartments and depths in the studied soil classes, with the highest proportions found in the reserve compartment, indicating the importance of this compartment for the supplement of these nutrients at average and long terms. The great majority of K, Ca and Mg compartments presented significant correlations between each other, showing the dependence between them and the importance of evaluating the contents of these nutrients in the different compartments to adapt the nutritional management of the plants to each soil class, and to obtain continuous productions, minimizing the negative effects to the environment. Plants cultivated in soils that present larger reserves, availability and K, Ca and Mg release kinetics, presented similar height (H), stem diameter (SD) and shoot dry mass (SDM), with or without fertilization with K, Ca and Mg. The plants presented higher leaf content and accumulation of K in all soils fertilized with K, Ca and Mg.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The fall armyworm Spodoptera frugiperda is one of the most important pests of maize. Various studies are conducted for their management, integrating chemical and biological control tactics as well as resistant plants. In order to offer alternatives for an efficient management of this pest with minimal use of pesticides, the technology of genetically modified plants resistant to insects has been widely studied. The aim of the present study was to evaluate the natural infestation of larvae of S. frugiperda and their injuries under field conditions in transgenic maize hybrids compared to their conventional isogenic counterparts at two sowing dates and two regions. The hybrids were planted in the off season of 2010 in Jaboticabal, SP, Brazil, and the summer of 2010/2011 in Jaboticabal, and Pindorama, SP, in a randomized block with seven treatments (hybrids) and four replications. Different levels of infestation of larvae occurred throughout the phenological development of plants in conventional and genetically modified hybrids with significant differences between the two groups in most evaluations. The hybrid 2B710HX was the least infested with caterpillars and had the least damaged leaf area. It follows that the Cry1F toxin was the most effective in protecting the plant in relation to other toxic proteins expressed by the other Bt hybrids against infestation and damage promoted by this pest, regardless of time of sowing.

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Cerrado é o segundo bioma brasileiro em biodiversidade e um dos mais ameaçados de extinção pelo desmatamento, por ser uma das últimas fronteiras agrícolas do planeta. Visando contribuir para o entendimento, preservação e exploração racional desse bioma conduziu-se um estudo utilizando três espécies da família Styracaceae: Styrax ferrugineus Ness & Mart., Styrax camporum Pohl. e Styrax pohlii A. DC. O objetivo foi quantificar e medir os teores de açúcares redutores (carboidratos livres totais) e não redutores (sacarose) e de amido foliar em indivíduos adultos de Styrax ferrugineus, Styrax camporum e Styrax pohlii durante a estação úmida (fevereiro/2011), o outono (maio/2011), a estação seca (agosto/2011) e o período de retomada das chuvas (outubro/2011). Testou-se a hipótese básica fundamental de que os referidos congêneres de Styrax alteram sazonalmente os teores de carboidratos solúveis, sacarose e amido nas folhas, assim como seus valores da área foliar específica (AFE). Para tal, as principais perguntas foram: Qual espécie tem um desempenho mais modulado pela sazonalidade?; Em qual época do ano os congêneres apresentam significativa redução dos teores de carboidratos?; Existe correlação entre AFE e teores de carboidratos?. Os resultados obtidos foram submetidos à analise variância e suas médias comparadas pelo teste de Tukey a 5 % de probabilidade. A baixa disponibilidade hídrica na estação seca alterou o metabolismo de carboidratos solúveis e o conteúdo de amido da parte aérea, sobretudo para S. camporum e S. pohlii. Já S. ferrugineus, bem adaptada ao Cerrado s. str., mostrou menor relação causal entre as estações e a concentração de amido na folha. As três espécies também alteraram sua AFE, correspondendo com a sazonalidade e o local de maior ocorrência, uma vez que S. camporum e S. pohlii apresentaram menor AFE no inverno. No entanto dados de S. ferrugineus indicam que no inverno suas...

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Pós-graduação em Agronomia (Horticultura) - FCA

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV