Fábio Alvares de Oliveira

Glyphosate reduces shoot concentrations of mineral nutrients in glyphosate-resistant soybeans.

Although glyphosate-resistant (GR) technology is used in most countries producing soybeans (Glycine max L.), there are no particular fertilize recommendations for use of this technology, and not much has been reported on the influence of glyphosate on GR soybean nutrient status. An evaluation of different cultivar maturity groups on different soil types, revealed a significant decrease in macro and micronutrients in leaf tissues, and in photosynthetic parameters (chlorophyll, photosynthetic rate, transpiration and stomatal conductance) with glyphosate use (single or sequential application). Irrespective of glyphosate applications, concentrations of shoot macro- and micronutrients were found lower in the near-isogenic GR-cultivars compared to their respective non-GR parental lines Shoot and root dry biomass were reduced by glyphosate with all GR cultivars evaluated in both soils. The lower biomass in GR soybeans compared to their isogenic normal lines probably represents additive effects from the decreased photosynthetic parameters as well as lower availability of nutrients in tissues of the glyphosate treated plants.

Marcha de absorção de macronutrientes na cultura do girassol

This study aimed to establish curves of macronutrient accumulation in sunflower. The experiment was conducted in the field on a Typic Hapludox, at the experimental station of Embrapa Soja in Londrina, State of Parana. The plots consisted of 14 25 m long rows spaced 0.70 m apart, resulting in a total area of 245 m2, with four replications. Prior to sowing a fertilization seeding of 300 kg ha-1 of 05-20-20 NPK fertilizer was applied. Fertilization was split in two applications of 25 + 1 kg ha-1 N and B, which were applied 21 and 35 days after sowing, respectively. The hybrid BRS 191 and a final plant density of 40,000 plants ha-1 were used. Plant samples were collected every two weeks after emergence and separated in the different parts (petioles, leaves, stems and, when applicable, capitula and achenes). After drying, each plant part was weighed and ground to determine the N, P, K, Ca, Mg, and S content. From the contents of these nutrients and dry mass of each plant, the accumulation curve was obtained. It was found that for yields > 3,000 kg ha-1, BRS 191 extracted about 150, 24, 286, 116, 42, and 24 kg ha-1 of N, P, K, Ca, Mg, and S, respectively, in the following order of extraction: K> N> Ca> P = S. In addition to the relation to exportation, the nutrient order was: N> P = K> S = Mg> Ca. Therefore, special attention should be paid to the maintenance of an adequate supply of N, K and Ca, due to the high demand of sunflower.

Características produtivas do trigo em função de fontes e doses de nitrogênio

Nitrogen fertilization is an important management practice in grasses and quite complex, due to several factors which influence it, such as climatic conditions, cropping systems and available levels and sources. This study aimed at evaluating the effect of topdressing nitrogen (N) sources and levels on the productive characteristics of wheat ( Triticum aestivum L.) grown after soybean, under no-till system. The experiment was conducted in an Oxisol, in Londrina, Parana State, Brazil. The experimental design was randomized blocks, in a 3x4 factorial scheme, with four replications. As topdressing N sources, urea, urea + urease inhibitor (NBPT) and polymer-coated urea were evaluated, in 2008, and urea, urea + urease inhibitor (NBPT) and ammonium sulfate, in 2009, in four doses (0.0 kg ha -1 , 40.0 kg ha -1 , 80.0 kg ha -1 and 120.0 kg ha -1 of N) applied 20 days after emergence. Plant height, lodging percentage, mass of 1,000 grains, grain yield and hectoliter mass were determined, and results showed that increased topdressing N levels promoted plants lodging, decreasing the mass of 1,000 grains, yield and hectoliter mass. The N sources did not affect the yield of the BRS Pardela cultivar grown after soybean.

Sunflower micronutrient uptake curves

Devido ao fato de a maioria dos trabalhos encontrados na literatura a respeito do acumulo dos micronutrientes [zinco (Zn), manganes (Mn), ferro (Fe), cobre (Cu) e boro (B)] no girassol serem antigos, objetiva-se, com este trabalho estabelecer curvas de acumulo de micronutrientes em um hibrido de girassol na condicao edafoclimatica dos tropicos. O experimento foi instalado no campo sobre Latossolo Vermelho distroferrico de textura argilosa, localizado na fazenda experimental da Embrapa Soja, em Londrina-PR, utilizando o hibrido comercial BRS 191. O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repeticoes. As unidades experimentais foram constituidas de 14 linhas, com espacamento de 0,70 m entre linhas e 25 m de comprimento, com densidade final de 42.858 plantas ha-1. As amostras das plantas foram coletadas em intervalos de 14 dias apos a emergencia. Apos cada coleta, dividiram-se as plantas em peciolo, folha, caule, capitulo e aquenios, sendo que as mesmas foram secas ate peso constante, quando foram tomados os pesos da materia seca e determinados os teores de Zn, Mn, Fe, Cu e B no tecido vegetal. A absorcao de micronutrientes ocorreu em maior velocidade a partir dos 42 dias apos a emergencia (DAE). O Fe foi o micronutriente mais absorvido, acumulando maior quantidade tanto nos aquenios como em relacao ao total absorvido. O acumulo total de Fe, Mn, Zn, B e Cu foram 38,06, 19,68, 9,20, 8,62 e 4,27 mg planta-1, respectivamente.

Acúmulo de nutrientes em soja convencional e soja RR em diferentes tipos de controle de planta daninha

The cultivation of soybean-Glycine max (Roundup Ready® - RR) has increased and little has been reported on the influence of glyphosate on the nutritional status of the plants. The aim of this work was to compare nutrient accumulation at different phenological stages between the cultivars BRS 184 (conventional) and BRS 243 RR (transgenic), with the same crop cycle, under different weed management systems (hand weed and herbicide). Nutrient accumulation and dry matter in conventional soybean was superior to that in the glyphosate-treated RR soybean, indicating that a higher level of nutrients might be required for the RR cultivars to achieve physiological efficiency and a new fertilizer recommendation for RR crops may be considered, due to the reduced nutritional efficiency imposed by glyphosate.

Produção, teor de boro e avaliação de extratores em solos cultivados com soja

Neste trabalho, objetivou-se avaliar a eficiencia de seis extratores de B e o efeito de doses sobre os teores de B e producao de materia seca da soja cultivada em condicoes de casa de vegetacao com LATOSSOLO VERMELHO Eutroferrico coletados em Maua da Serra e Londrina (PR) e NEOSSOLO QUARTZARENICO Ortico de Alto Garcas (MT). O delineamento experimental utilizado foi o inteiramente casualizado, constituido por seis doses de B (0, 0,25, 0,5, 1, 2 e 4 kg ha-1), com tres repeticoes. O B disponivel foi determinado por seis solucoes extratoras: Mehlich 1, Mehlich 3, agua quente, HCl 0,05 mol L-1, Ca(H2PO4)2.H2 O 0,01 mol L-1 e KCl 1,0 mol L-1. Nas condicoes estudadas, os resultados mostraram que o B extraido por agua quente acarretou as melhores correlacoes com a producao de materia seca e conteudo de B na planta, enquanto o extrator KCl 1,0 mol L-1 foi o mais eficiente na determinacao do teor de B no tecido vegetal. Altas concentracoes de B diminuiram a eficiencia do extrator agua quente em determinar o B disponivel do solo. As maiores correlacoes foram obtidas entre os extratores Mehlich 1 e Ca(H2PO4)2.H2 O 0,01 mol L-1, KCl 1,0 mol L-1 e HCl 0,05 mol L-1, KCl 1,0 mol L-1 e Ca(H2PO4)2.H2 O 0,01 mol L-1 e agua quente e Ca(H2PO4)2.H2 O 0,01 mol L-1.