The typical nitrogen supply recommendation for soybeans is the application of inoculant with no additional required supplementation via fertilization. However, the adoption of no-till farming, the release of high-yielding cultivars and recent studies concerning soybean response to late application of nitrogen have sparked doubts about the possible benefits of nitrogen fertilization. Recent studies using nitrogen fertilization of soybeans show no increase in yield, due to efficient biological fixation (BNF); however, the effects of different application times have not been widely studied. In this context, the aim of this study was to investigate different methods and times of nitrogen fertilization of soybeans. Using the recommended supplements, along with a search of the scientific literature on the same theme, nine treatments were evaluated. These consisted of the application of single and split doses of nitrogen, at 20 kg.ha -1 and 40 kg.ha -1 , during sowing and reproductive stage R4. The nitrogen source used was urea (45% nitrogen). It was applied in adequate environmental conditions, at levels typically found in rain forecasts, and were incorporated into the soil to avoid losses by volatilization. The split application of nitrogen (at sowing + stage R4) provided an increase in yield, reaching a 47% difference in treatment 6 in relation to control, not taking into account supplementation costs. Furthermore, the variables related to plant architecture displayed no significant differences.

Allelochemicals are important and innovative tools for weed control as they neither harm the environment nor increase weed management costs. The secondary metabolites can be extracted by water or soaking and later applied in soil or leaves. This study evaluated the leaf extracts of Cymbopogon citratus, affecting germination of Bidens pilosa and B. subalternans seeds. Two trials were conducted in germination chambers. The completely randomized design was employed in both trials with 5 replications. Trial one was arranged in a 2×3 double factorial design, with two periods of leave collection (morning and afternoon); and three extract preparations (aqueous extract by maceration, aqueous extract by infusion and control with distilled water). Trial two was set up in a 2×2×5 triple factorial design, with two extracts (aqueous extract by maceration, aqueous extract by infusion); two time of day collection (morning and afternoon) and five extracts concentrations (0; 25; 50; 75 and 100%). The means were compared by F and Tukey's test (p ≤ 0.05). To evaluate extracts concentrations a regression analysis was run. The results showed that the aqueous extract by maceration of C. citratus decreased germination and germination speed of Bidens pilosa and Bidens subalternans more than the aqueous extract by infusion, for both species. The concentrations interfered, inversely and proportionally, decreasing germination and germination speed. The germination of beggarticks was affected by the extracts of C. citratus, suggesting further studies for this plant.

A planta de pinhão manso encontra-se entre as culturas com grande potencial energético, devido à grande concentração de óleo nas suas sementes, e seu alto poder calorífico. Entretanto, a maturação desuniforme é um problema na colheita, principalmente levando em consideração o melhor momento para se colher os frutos visando maior rendimento de óleo. Neste sentido, este trabalho teve como objetivo avaliar quais características dos frutos de pinhão manso indicam a melhor época para colheita visando maior rendimento de teor de óleo nas sementes. Para tal, coletaram-se em 2013 e 2014 frutos de pinhão-manso em diferentes estádios de maturação: frutos verdes escuros (VE), frutos amarelos (AM), frutos marrom-amarelados (MA) e frutos marrons na planta (MP). Destes, avaliou-se, tanto das sementes como dos frutos, o comprimento, largura, espessura e a massa seca. Dos frutos avaliou-se ainda a porcentagem de umidade, e das sementes avaliou-se o teor de óleo. Tanto em 2013 como em 2014, para as variáveis relacionadas com dimensões (comprimento, largura e espessura), tanto nos frutos como nas sementes, as maiores médias foram obtidas pelos frutos verdes. Em contrapartida, tanto para os frutos como para as sementes, observou-se que os frutos mais maduros apresentam maior matéria seca onde obteve-se médias de 60,28% e 92,52 em 2013 e 62,79% e 80,31% em 2014 respectivamente para MA e MP. Já quanto ao teor de óleo os estádios de maturação mais adequados à colheita de pinhão manso encontram-se imediatamente após o amarelecimento dos frutos, quando os mesmos apresentam quantidade de óleo mais elevada.

-The weed management in soybean cultures stands out as an important tool to ensure its high yield potential. The direct tillage advent increased the importance of management performed in the soybean off season and pre-seeding, in order to avoid the weeds interference in the initial cultivation period. The survey was conducted in order to evaluate the weeds control and the agronomic performance of conventional soybean, using different desiccant herbicides. The experiment was conducted in randomized blocks design with four replications. Treatments were arranged in factorial 4x3, the first factor being the glyphosate herbicides applicationdiisopropylamine salt; glyphosate -potassium salt, glyphosate isopropylamine-salt + 2,4-D; and paraquat + diuron, the second factor the application time periods (13 and 7 days before seeding -DBS; and 1 day after seeding -DAS). The percentage of weed control, booth, seedling emergence, plants height, number of pods, mass of hundred seeds and productivity were evaluated. Only the management desiccation with glyphosate near the seeding time showed a decrease in the weeds control percentage, the glyphosate + 2,4-D use led to a decrease in the early crop growth, due to seeding proximity, the paraquat + diuron application near the seeding season caused a lower insertion of the first pod in the culture. There were no significant differences between treatments for soybean production components under these experimental conditions.