The management of nitrogen fertilization is complex due to the various transformations of the nitrogen that occur in the soilplant-atmosphere system, reducing the efficiency of the fertilization, productivity and the profit margin of the maize production areas. This study aimed to evaluate the effect of different levels of common urea and urea treat with NBPT [N-(n-butyl) thiophosphoric triamide] on the productivity and efficiency of the nitrogen fertilization in maize, correlated with simple economic analysis. The design of the field experiment was in randomized complete blocks with six repetitions, in a 2 x 4 factorial outline, made up of by two sources of nitrogen (urea and NBPT-treated urea) and four levels of nitrogen as top dressing (60, 120, 180 and 240 kg ha -1 ). The sources and applied nitrogen levels influenced the productivity and the leaf and grain nitrogen contents, while the production components (size and diameter of the ear, and percentage of straw and cob) were not altered. The agronomic efficiency of the nitrogen fertilization decreased with the increase of the applied nitrogen levels. The highest gross profit margin in the maize culture is obtained with 180 kg ha -1 of nitrogen supplied in the NBPT-treated urea.Index terms: Zea mays, nitrogen, urease inhibitor, agronomic efficiency, gross profit margin. RESUMOO manejo da adubação nitrogenada é complexo em razão das diversas transformações do nitrogênio que ocorrem no sistema solo-planta-atmosfera, diminuindo a eficiência da adubação, produtividade e a margem de lucro das áreas de produção de milho. Neste trabalho, objetivou-se avaliar o efeito de diferentes doses de uréia comum e com NBPT [N-(n-butyl) thiophosphoric triamide] na produtividade e eficiência da adubação nitrogenada na cultura do milho, correlacionado com análise econômica simples. O delineamento experimental foi em blocos completos casualizados com seis repetições, em esquema fatorial 2 x 4, constituídos por duas fontes de N (uréia comum e uréia tratada com NBPT) e quatro doses de nitrogênio em cobertura (60, 120, 180 e 240 kg ha -1 ). As fontes e doses de nitrogênio influenciaram na produtividade e nos teores de N da folha e dos grãos, enquanto que os componentes de produção (tamanho e diâmetro da espiga e porcentagem de palha e sabugo) não foram alterados. A eficiência agronômica da adubação nitrogenada diminuiu com o aumento das doses de N aplicadas em cobertura. A maior margem bruta de ganho da cultura do milho é obtida com aplicação de uréia tratada com NBPT, na dosagem de 180 kg ha -1 . Termos para indexação:Zea mays, nitrogênio, inibidor da urease, eficiência agronômica, margem bruta de lucro.
-Heterosis and its components were evaluated in a diallel crossing system of sweet corn. In the 38 treatments, eigth parents, 28 hybrids and two controls were used, arranged in a randomized block design with three replications.The diallel analysis followed the methodology of Gardner and Eberhart (1966
INTRODUÇÃOUm dos maiores obstáculos à produção e livre comercialização de frutos frescos, no Brasil e no mundo, é a presença das moscas-das-frutas (Diptera, Tephritidae), nas áreas comerciais, devido aos danos diretos causados por suas larvas, no interior dos frutos, e às restrições quarentenárias impostas por países importadores destes produtos (Malavasi 2000 Fruit flies (Diptera, Tephritidae) in the Goiás State, Brazil: occurrence and distributionThe Goiás State, in Brazil, presents a high number of host plant species for fruit flies, whose fruits ripen at different seasons, providing an increase in the pest population density and its wide distribution. Throughout the Goiás State, fruit flies occur in high or low frequency, both in rural and urban areas. Besides the Mediterranean fruit fly (Ceratitis capitata), 21 species of Anastrepha flies are currently known, mainly A. obliqua, A. fraterculus, A. sororcula and A. zenildae, due to their economic importance, and A. grandis, for being a quarantine pest. The A. grandis species has been recorded in 13 cities in the Goiás State, however, this information does not preclude the fruits export programs implemented in the State, because it was observed, in the production units, that the FTD index (flies trap -1 day -1) was lower than 0.1, in accordance with the rates established by the Brazilian legislation, for the export of cucurbit fruits. KEY-WORDS: Ceratitis spp.; Anastrepha spp.; fruits pests. ARTIGO DE REVISÃO
Rainfall is among the climatic factors that most affect production, as in the Brazilian Cerrado. Non-destructive and automated phenotyping methods are fast and efficient for genotype selection. The objective of this work was to evaluate, under field conditions, the morphophysiological changes, yield, and grain quality of soybean (Glycine max L. Merrill) under water stress in the Brazilian Cerrado. The plots comprised six soybean cultivars and the subplots of four water regimes, corresponding to 31, 44, 64 and 100% of crop evapotranspiration replacement. The experiments were conducted from May to September 2018 and 2019. An irrigation system with a bar of sprinklers with different flow rates was used. Gas exchange, vegetation indices (measured using a hyperspectral sensor embedded in a drone), yield and grain quality were evaluated. Water stress had different effects on gas exchange, vegetation indices, grain yield and chemical composition among the cultivars. Embrapa cultivar BRS 7280 Roundup ready (RR) and Nidera cultivar NA 5909 RG (glyphosate resistant) are yield stable and have a greater tolerance to drought. BRS 7280RR showed a higher tolerance to drought and higher water use efficiency (WUE) than all other tested cultivars. Vegetation indices, such as the NDVI (Normalized Difference Vegetation Index), correlated with the morphophysiological traits, such as plant height, were the most responsive variables to water stress. The NDVI can be used to predict soybean yield as a tool in a selection program under drought.
Resumo -O objetivo deste trabalho foi determinar o controle genético do teor de proteína em grãos e de caracteres agronômicos de milho (Zea mays) cultivado com diferentes níveis de adubação nitrogenada. Foram avaliados nove genitores de milho e seus híbridos, em dialelo completo, com dois níveis de adubação nitrogenada. Os caracteres avaliados foram: índice relativo de clorofi la, altura de plantas, altura de espigas, produção de espigas, produção de grãos, coloração de grãos, massa de cem grãos, densidade de grãos, teor de nitrogênio nas folhas e teor de proteína nos grãos. A elevação da adubação nitrogenada promoveu aumento nos caracteres índice relativo de clorofi la, altura de espigas e teor de proteínas nos grãos. Apenas a variável produção de grãos apresentou controle genético distinto nos diferentes níveis de nitrogênio. A análise dialélica mostrou signifi cância dos efeitos dos genótipos sobre todos os caracteres, com exceção da produção de espigas e de grãos, e foi possível observar signifi cância da heterose na maioria das variáveis. Para o teor de proteínas nos grãos, não houve signifi cância da capacidade específi ca de combinação, e a capacidade geral de combinação dos genótipos teve efeito mais importante na manifestação desse caráter.Termos para indexação: Zea mays, análise de dialelo, capacidade de combinação, qualidade da proteína. Genetic control of grain protein content and of agronomic traits in maize cultivated at different levels of nitrogen fertilizationAbstract -The objective of this work was to determine the genetic control of grain protein content and of the agronomic traits of corn (Zea mays) at different levels of nitrogen fertilization. Nine parent populations and their hybrids were evaluated in a complete diallel mating design, with two levels of nitrogen fertilization. The variables evaluated were: relative chlorophyll index, plant height, ear height, ear production, grain yield, grain color, mass of 100 grains, density of grains, nitrogen content in the leaves and grain protein content. Increasing levels of nitrogen fertilization increased the relative chlorophyll index, ear height and grain protein content. However, only grain production had distinct genetic control at different levels of nitrogen. Diallel analysis showed signifi cant genotype effect in all traits, except for grain and ear production. For most of the variables, there was signifi cance of heterosis effect. For grain protein content, there was no signifi cance for specifi c combining ability, and genotypes general combining ability had more important effects in the expression of this character.Index terms: Zea mays, diallel analysis, combining ability, protein quality. IntroduçãoO milho é tido como uma das principais culturas do mundo, e sua importância está associada à versatilidade em sua utilização, pois é considerado um alimento energético para dietas humanas e animais, com potencial para ser aproveitado também como fonte proteica (Paes, 2006). No entanto, o melhoramento genético voltado principalmente para o ...
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