ABSTRACT. The effect of liming on the availability of micronutrients to soybean cultivated during different numbers of years under no tillage (NT) was investigated. The treatments consisted of the number of years under NT (three, six, and nine years) and five rates of lime (0, 33, 67 and 100% of the amount calculated to raise soil base saturation to 70%) broadcast on soil surface plus the rate of 100% broadcast with incorporation in the 0-0.20 m layer of a clayey Red Oxisol. Soil and leaf samples were collected at two vegetative stages of the crop (vegetative V4 and blossoming R2). The soil was sampled at depths of 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m. Surface liming had little effect on extractable soil micronutrient and nutrient concentrations in soybean leaves. In the area with three years under NT, all liming rates decreased the extractable soil Zn up to a depth of 0.20 m. Lime incorporation decreased the extractable soil Mn in the surface layer. There were no differences in the extractable soil micronutrients and nutrient concentrations in soybean leaves as a function of the number of years under NT. These data suggest that broadcasting lime at current rates on soils under NT does not necessarily lead to micronutrient deficiencies.Keywords: copper, iron, manganese, zinc, no till.Efeito da calagem na disponibilidade de micronutrientes para soja, cultivada em solo sob diferentes tempos de cultivo em plantio direto RESUMO. Avaliou-se o efeito da calagem sobre a disponibilidade de micronutrientes à soja cultivada em solo, com diferentes tempos de cultivo sob sistema de semeadura direta (SD). Os tratamentos consistiram de número de anos sob SD (três, seis e nove anos) e cinco doses de calcário (0, 33, 67 e 100% da quantidade necessária para elevar a saturação por bases a 70%), aplicadas em superfície, mais a dose 100% incorporada na camada 0-0,20 m de um Latossolo Vermelho argiloso. Amostras de solo e de folha foram coletadas em dois estádios de vegetação da soja (V4: estádio vegetativo e R2: florescimento pleno). O solo foi amostrado nas profundidades de 0-0,05, 0,05-0,10, 0,10-0,20 e 0,20-0,30 m. A calagem superficial exerceu pouco efeito sobre os teores de micronutrientes no solo e nas folhas de soja. Na área com três anos sob sistema de SD todas as doses de calcário reduziram os teores de Zn até a profundidade de 0,20 m. A incorporação de calcário diminuiu o teor de Mn da camada superficial. Os teores de micronutrientes no solo e as concentrações nas folhas da soja não variaram com os anos de cultivo sob SD. Estes dados sugerem que as doses atualmente empregadas de calcário aplicadas na superfície de solos sob SD não necessariamente conduzem a deficiências de micronutrientes.Palavras-chave: cobre, ferro, manganês, zinco, plantio direto.

O molibdênio (Mo) está associado aos processos de metabolismo do nitrogênio (N) devido a sua participação na formação e na atividade da redutase do nitrato. A deficiência de Mo pode acarretar também deficiência de N, comprometendo o rendimento das culturas. Objetivou-se avaliar o efeito de doses de Mo na produtividade do milho e na concentração de nutrientes nas folhas. Foi utilizado o delineamento experimental em blocos casualizados com quatro repetições. Os tratamentos foram constituídos de seis doses de Mo: 0, 25, 105, 210, 315 e 420 g ha-1. Como fonte de Mo, empregou-se o molibdato de sódio, suspensão concentrada, com 25 % de Mo. Avaliaram-se os teores de nutrientes nas folhas, na época do florescimento, e a produtividade de grãos do milho. Os dados foram submetidos a análises de variância 5 % de significância. Os atributos avaliados não se modificaram com as doses de Mo. A ausência de resposta à aplicação de Mo foliar pode ser devido às quantidades adequadas do  nutriente no solo como também nas sementes.

The objective of this work was to evaluate macronutrient uptake and export by transgenic corn hybrids under medium and high fertilization levels. For each fertilization level, a randomized complete block design was carried out in the summer crop season, under no-tillage and supplementary irrigation, with four cultivars and four replicates. Plants were sampled throughout the entire cycle and separated into leaves, stalk, husk, cob, and grains for the determination of dry matter mass and accumulation of macronutrients in the different growth stages. Under the high fertilization level, a greater dry matter mass and nutrient uptake were observed, but grain yield was similar to that under the medium fertilization level. The uptake of N, P, Ca, Mg, and S occurs until later in the cycle of the transgenic cultivars, which also showed lower concentrations of P, K, and S in grains, when compared to older hybrids. The differential behavior of the evaluated cultivars under different fertilization levels indicates the need of updating and improving nutritional management and fertilizer recommendations for the corn crop.

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Non-thermal energy sources have been utilized to control diseases and boost the physiological quality of maize seeds. The aim of this paper was to assess the impact of UV-c exposure and ozone application, associated or not, on organic maize seed germination and seedling vigor. Three cultivars (BRS Caimbé, BRS 1060 and BR 451), three exposure levels to ozone (15, 30 and 60 minutes) in the absence and presence of ultraviolet radiation (UV-c), were used in a completely randomized design with a factorial scheme of 3 x 3 x 2 + 3 (additional treatments) experiment. Evaluations of electrical conductivity, emergence in soil, and germination (at 4th and 7th day) on paper roll were done. Daily measurements of the emerged seedlings were taken up to the 14th day after emergence. The measurements included total emergence (EC), coefficient of variation in emergence time (CVt) in percentage, coefficient of emergence velocity (CVe) in percentage, emergence rate index (ERI) in days, and emergence synchronization index (Z). The tested genotypes caused differences in all studied variables. Increasing the percentage with a 30-minute exposure to ozone in the presence of UV-C radiation resulted in a validated enhance in the first germination reading. The association of O3 and UV-c techniques can be used to treat organic maize seeds without significantly affecting their physiological quality.