Resumo O objetivo deste trabalho foi avaliar a eficiência de fontes e doses de magnésio solúvel (MnSO4.H2O) e insolúvel (MnCO3) nos processos de absorção, transporte e redistribuição deste nutriente na soja (Glycine max), bem como na produtividade da cultura, em solo de Cerrado. O delineamento experimental foi em blocos ao acaso, em arranjo fatorial 4×2 – quatro doses (150, 250, 350 e 450 g ha−1) × duas fontes (MnSO4.H2O e MnCO3) de Mn –, com quatro repetições. Nas safras de 2015/2016 e 2016/2017, realizaram-se adubações foliares no terceiro trifólio e avaliaram-se os conteúdos de Mn e a produtividade da soja. Em ambas as safras, a fertilização foliar com Mn aumentou os teores do nutriente nas folhas, nos caules e nos grãos, mas não afetou o rendimento de grãos e a produção de matéria seca. Os teores máximos de Mn nas folhas foram obtidos com doses entre 150 e 450 g ha−1. A aplicação de MnSO4.H2O aumentou a absorção, o transporte e a redistribuição de Mn na planta, com desempenho superior ao de MnCO3. A fertilização foliar com MnSO4.H2O em soja, em solo de Cerrado, aumenta os teores de Mn nas folhas, mas não a produtividade e a produção de matéria seca.

Abstract The objective of this work was to evaluate the efficiency of sources and rates of soluble (MnSO4.H2O) and insoluble (MnCO3) manganese on the processes of uptake, transport, and redistribution of this nutrient in soybean, as well as on crop yield, in Cerrado soil. The experimental design was randomized complete blocks in a 4×2 factorial arrangement – four rates (150, 250, 350, and 450 g ha−1) × two sources (MnSO4.H2O and MnCO3) of Mn –, with four replicates. In the 2015/2016 and 2016/2017 crop seasons, foliar fertilizations were carried out on the third trifoliate leaflet, and Mn content and soybean yield were evaluated. In both crop seasons, Mn foliar fertilization increased the contents of the nutrient in leaves, stems, and grains, but did not affect grain yield and dry matter production. The maximum Mn contents in leaves were obtained with rates between 150 and 450 g ha−1. The fertilization with MnSO4.H2O increased Mn uptake, transport, and redistribution in the plant, with a performance superior to that of MnCO3. Foliar fertilization with MnSO4.H2O in soybean, in a Cerrado soil, increases Mn contents in the leaves but not yield and dry matter production.

ABSTRACT: The utilization of insoluble sources of micronutrients as concentrated suspensions (CSs) is increasing in Brazilian agriculture; however, much information regarding the physicochemical characterization of these products is required to demonstrate the absorption behavior by plant leaves. This study aimed to characterize the CSs available on the Brazilian market to support their potential use as foliar fertilizers. We selected five CSs containing Mn, five CSs containing Zn and three CSs containing Cu from five different companies. In each product, the mean particle size was evaluated by dynamic light scattering (DLS), the particle shape and size were evaluated by scanning electron microscopy (SEM), the aggregation degree was determined by the zeta potential and the heavy metal contents were determined by acid digestion followed by reading on ICP-OES. The mean hydrodynamic diameter of fertilizers containing Cu, Mn and Zn was 315 ± 55, 378 ± 184 and 435 ± 107 nm, respectively. The zeta potential varied from –20 to –30 mV, indicating potential particle aggregation and formation of higher structures. SEM images indicated great variation in the size and shape of the particles in each product. All products exhibited concentrations of toxic elements within the legislation thresholds. The average particle size of CSs currently marketable in Brazil does not allow their classification as nanomaterials (< 100 nm). Therefore, their foliar absorption is unlikely, once the particle size is higher than the exclusion limit observed for stomata and cuticle pathways, as well as the nutrient content as ions is low according to the solubility constant.

O objetivo do trabalho foi avaliar a influência do arranjo espacial, via redução de espaçamento entre linhas de plantas, na cultura do milho em dois solos de baixa altitude no Oeste do Estado do Paraná, Brasil. Os trabalhos foram conduzidos em duas áreas experimentais da Cooperativa C.Vale, no ano agrícola de 2014/15, uma situada em Palotina (solo muito argiloso) e a outra em Brasilândia do Sul (textura média), em que o delineamento experimental foi o de blocos casualisados, com quatro repetições. Os tratamentos foram dispostos em modo fatorial duplo 2x4 (Híbridos X Espaçamentos) e os híbridos de milho utilizados foram o 2B587PW e o 2B810PW. Os espaçamentos entre as linhas foram de 25, 50, 75 e 100 cm. Os híbridos de milho foram semeados e mantidos com uma população de 70 mil plantas por hectare. As variáveis analisadas foram: altura de plantas e diâmetro do colmo; número de plantas acamadas; número de espigas danificadas; número de espigas expostas; percentagem de grãos ardidos; massa de 100 grãos e produtividade. A melhor disposição de plantas nos solos de baixa altitude, foi conferida pela redução do espaçamento entre as linhas e o aumento do espaçamento entre plantas na linha.

The aim of this work was to evaluate the influence of the spatial arrangement, by reducing spacing between plant lines, on maize cultivation in two low altitude soils in the western part of the State of Paraná, Brazil. The studies were conducted in two experimental areas of Cooperativa C.Vale, in the agricultural year of 2014/15, one located in Palotina (very clayey soil) and the other in South Brasilândia (medium texture), in which the experimental design was the randomized blocks with four replicates. The treatments were arranged in a 2x4 double factorial (Hybrids X Spacings) and the corn hybrids used were 2B587PW and 2B810PW. The lines spacing were 25, 50, 75 and 100 cm. Corn hybrids were sown and maintained with a population of 70 thousand plants per hectare. The analyzed variables were: height of plants and diameter of stems; number of bedded plants; number of damaged spikes; number of exposed spikes; percentage of burned grains; mass of 100 grains and productivity. The best arrangement of plants in soils at low altitude was conferred by the reduction of line spacing and the increase of plant spacing in the line.