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ABSTRACT: Aerobic respiration declines in the root tissue of soybean plants exposed to waterlogged soil with a low oxygen content, causing metabolic disorders that negatively affect gas exchange and photosynthetic activity, hampering growth and production. As such, this study to investigated daytime gas exchange, relative chlorophyll content, specific leaf area (SLA) and photosynthetic activity curves in response to photosynthetic photon flux density (PPFD) in soybean plants grown under different conditions: no stress (control), shading, waterlogged soil, and waterlogged soil + shading. Soybean plants exposed to either waterlogging or shading and both conditions simultaneously exhibited reduced photosynthesis linked to lower stomatal opening. Plants submitted to shading showed an increase in SLA, quantum yield and photosynthetic rates, while those grown in waterlogged soil, in full sun, exhibited chlorotic leaves and low apparent quantum yield, resulting in low photosynthetic rates under shading and high light levels. Thus, waterlogging and shading in isolation or combined, compromise daytime gas exchange and alter photosynthetic activity in plants.

In both arid and semi-arid regions, adopting field mulching can effectively optimize soil moisture distribution, enhance crop yields, and improve water productivity. While acknowledging its advantages, field mulching seems insufficient for maintaining high crop productivity due to the increasing frequency of extreme weather. Furthermore, drought often coincides with critical crop growth stages, necessitating the implementation of agricultural irrigation to ensure normal crop growth. Accordingly, we conducted a three-year field experiment from 2021 to 2023 including three typical field mulching methods (no mulching, NM; straw mulching, SM; plastic film mulching, FM) and three supplementary irrigation strategies (irrigated at the branching stage (V4), W1; irrigated at the pod-filling stage (R2), W2; irrigated at both the V4 and R2 stage, W3). Throughout the entire growth period, we monitored soil moisture conditions for each treatment, measured leaf physiological parameters at crucial growth stages, and assessed soybean yields and water productivity (WP). Our findings indicated that, relative to SM and NM, FM maintains optimal soil moisture balance, augments chlorophyll content, and enhances photosynthesis, resulting in an average yield increase of 17.0% and 38.3% over three growing seasons. Additionally, supplementary irrigation also significantly affects the growth and seed yield of soybean. FMW2 achieved the higher seed yield (4307.5 kg ha−1, 3-year averaged), had insignificant difference with the highest seed yield of 4568.6 kg ha−1, both significantly higher than other treatments. Similarly, the leaf area index, chlorophyll content, net photosynthetic rate (Pn) and transpiration rate (Tr) also presented insignificant difference between FMW2 and FMW3, while WUEleaf (Pn/Tr) of FMW2 obviously higher than that of FMW3. As a result, FMW2 achieved the highest WP of 12.2 kg ha−1 mm−1 over the three growing seasons, compared to the three-year average of the other treatments, the increase ranges from 5.6% to 46.7%. In summary, the FMW2 treatment optimized water distribution to meet the water demands of soybeans during the reproductive growth stages, achieving a beneficial balance between soybean seed production and WP by regulating leaf functional parameters. Future research will explore more specific irrigation scheduling techniques (e.g., precision irrigation, deficit irrigation, and sensor-based irrigation management systems) while integrating innovative agricultural film materials (e.g., biodegradable films) to further enhance crop resilience and productivity under evolving climatic conditions.

ABSTRACT present study aimed to determine the effects of different light restriction levels (shading levels) on soybean genetic parameters using a Bayesian multi-trait model (MTM) and select high-yielding soybean cultivars. Eighteen commercial soybean cultivars bred in a soybean breeding program were evaluated over two agricultural seasons. Three shading levels were used over two agricultural crop seasons, giving six treatments (light restriction × crop season). The experiments were arranged in a randomized complete block design with six treatments replicated thrice. The genetic values and parameters were estimated using a Monte Carlo Markov Chain algorithm. Broad-sense heritability range from 0.2093 to 0.7153. The lowest genotypic variance estimate was observed at the 45 % photosynthetically active radiation level in the 2019/2020 crop season year compared with that of other shading levels. Furthermore, a 40 % selection intensity had the highest soybean yield under different shading levels. The Bayesian MTM combined with the factor analysis and genotype-ideotype distance method can be used to evaluate and select soybean genotypes considering different shading levels. The soybean cultivars 8579RSF, NS8338, NS7901, NS7667, RK8115, and 8473RSF had higher genetic potential than other cultivars under different shading levels.

ABSTRACT Integrated agricultural production systems have been improved with the introduction of Urochloa grasses aiming at obtaining straw for a no-tillage system (NTS) and the increase of legumes, which promote physicochemical improvements in soils and guarantee intensification and sustainability of production. This study aimed to evaluate the agronomic traits and yield of soybean in succession to the intercropping of corn with marandu grass and/or pigeonpea in five populations of plants harvested for silage production. The experiment was carried out in the Cerrado region of Selvíria, MS, Brazil, during the 2016/17 and 2017/18 agricultural years, in an Oxisol. The experimental design consisted of randomized blocks, with four replications. The treatments were arranged in a 2×5 factorial scheme, consisting of off-season corn intercropped with pigeonpea (Cajanus cajan (L.) Millsp.) and off-season corn intercropped with marandu grass (Urochloa brizantha) and pigeonpea, in addition to five sowing densities (0, 6, 12, 18, and 24 seeds m-1). Soybean was planted in succession aiming to evaluate the effect of remaining straw on crop performance. Soybean grown in succession to the triple intercropping of corn with marandu and pigeon pea shows increased productivity.

ABSTRACT It is projected an increase of about 30% in the world population by 2050 and a food demand increase by 60%, mainly vegetable proteins. Due to this, soybean is being introduced in new production systems, such as in rotation with irrigated rice in lowlands. Irrigated and non-irrigated experiments were conducted in order to determine the influence of irrigation on maturity groups, on yield components and yield in lowlands. Five soybean cultivars with maturity groups (MG) ranging from 4.8 to 7.8 were used, representing the cultivars sowing in southern Brazil, and three sowings were performed (October, November and January). A decrease in the number of pods m-2 was observed with the delay in the sowing date in both water regimes and MG, except MG 4.8 and 5.5, which had a higher number of pods m-2 when irrigated and sown in November. The leaf area index (LAI) was higher under the irrigated condition, for all MGs and sowing dates. The interaction between the yield components can be maximized by the combination of supplemental irrigation, anticipation of sowing date and the choice for cultivars with MG from 6.2 to 6.8 for lowland environments.

In the study, humic acid was applied to soybean (Glycine max L.), which has high economic value and importance, to determine the tolerance level of the plant against salt stress, and physical and chemical changes in the plant were observed. The study was carried out in the climate room of Van Yuzuncu Yil University Faculty of Agriculture, Department of Field Crops in 2019. In the research, İlksoy soybean variety was used. The experiment was carried out in 4 factorial orders according to the factorial experiment was designed based on Completely Randomized Design. In the research, four different Humic acid doses (0, 500, 1000 and 2000 ppm) and 3 different NaCl salt doses (0, 125 and 250 mM) were used. In the study, root length, stem length, root fresh weight, stem fresh weight, root dry weight, stem dry weight, leaf area, chlorophyll content, ion leakage in leaf tissues, lipid peroxidation level (MDA), relative water content and membrane resistance index in leaf tissues were determined. Properties such as index were also examined. As a result of the study, the longest root was 38 cm for the control plots that salt and humic acid didn’t apply to the plants. The highest root fresh weight was 2.08 g and the stem fresh weight was 1.87 g of the plots where 500 ppm humic acid dose applied. In addition, the plants with the highest chlorophyll ratio was 51.05 under 250 mM salt applied without humic acid application.

ABSTRACT The objective was to study the adaptability and stability of soybean cultivars in the lowland production system under different conditions in a subtropical environment. Fourteen soybean cultivars were evaluated in five locations and three growing seasons in Rio Grande do Sul State, Brazil. Three sowing dates were evaluated in each location and growing season and named as: early, recommended for high yield and recommended to minimize the risk of water deficiency. The experiment was carried out in a randomized complete block design, with three replicates. Yield data was submitted to analysis of variance, and the Eberhart and Russel method was used to study its adaptability and stability. In general, the cultivars that showed adaptability and stability to the three sowing dates showed MG between 5.6 to 6.4 and the type of indeterminate growth. The cultivars A6411 RG, TEC 5936 IPRO and TECIRGA 6070 RR combined wide adaptability and stability, the cultivars Fundacep 65 RR and 6869 RSF RR presented high yield and stability of production and are recommended for lowland environments.

O cobre (Cu) é um metal pesado que nas doses adequadas é essencial para as plantas, mas em doses elevadas potencialmente pode ser tóxico às espécies agrícolas. Contudo, a utilização de bactérias fixadoras de nitrogênio pode ser uma alternativa para o cultivo de soja em área contaminado com cobre. A tolerância ao excesso de Cu pelas raízes se dá com a imobilização do Cu na parede celular, exclusão ou restrição da absorção, compartimentalização no vacúolo com complexos solúveis. Objetivou-se neste trabalho determinar a influência do uso de bactérias fixadoras no desenvolvimento, resposta fisiológica e na bioacumulação de cobre na soja cultivada em solo contaminado. O delineamento experimental foi inteiramente casualizado em arranjo fatorial 7 x 2, sendo, sete doses de cobre (0, 80, 160, 240, 320, 400 e 480 mg de cobre kg -1 de solo), duas inoculações (com Bradyrhizobium japonicum e sem inoculação - testemunha), com 8 repetições. Avaliou-se a altura da parte aérea, diâmetro do colo, número de grãos por planta, massa seca da parte aérea e sistema radicular, área foliar, área superficial específica de raízes, teores de cobre na parte aérea, radicular e grãos, índice de translocação e tolerância, fator de bioconcentração, coeficiente de bioacumulação, parâmetros da clorofila, número e massa seca de nódulos. A inoculação com B. japonicum proporciona incrementos nos caracteres fisiológicos, na altura de planta, área superficial específica de raízes e no rendimento de grãos da soja em solo contaminado com cobre. A soja apresenta baixa eficiência em translocar o cobre para parte aérea, porém seu teor no grão inviabiliza sua recomendação de cultivo em solo contaminado com este metal.

The use of multispectral images has great potential to assess seed quality and represents a significant technological advance in the search for fast and non-destructive analysis techniques. However, the devices currently available are expensive. Thus, this study aimed to propose a low-cost method for acquisition and processing of multispectral images of soybean seeds and to evaluate their potential for rapid determination of seed physiological potential. The study was conducted in three steps: implementation of the multispectral image acquisition system, development of an algorithm for automatic image processing, and evaluation of the relationship between the data obtained through image analysis and the results of standard tests used to evaluate seed physiological potential. A total of 43 variables were assessed, eight related to seed physiological potential (germination and vigor) and 35 obtained from the analysis of the multispectral images. Of the variables obtained from multispectral images, 21 were related to pixel values in the images in the different bands evaluated (green, red, and infrared) and 14 associated with seed morphometric characteristics. The proposed system is efficient in obtaining multispectral images and the algorithm developed was efficient to extract morphometric characteristics and pixel information from the images. The parameters obtained from the NIR spectrum region showed a good relationship with the physiological potential of soybean seeds.

The arrangement of soybean plants defines their ability to recognize the environment and improve their abiotic and biotic interactions with it. This study aimed to evaluate the effect of planting arrangements associated to two distinct crop systems (high technological level or conventional crop level) for the soybean varieties 8473 RSF and AS 3730, to evaluate the plant performance and productivity in the field. A double factorial scheme was used with two varieties and six spatial arrangements. Two experiments were conducted during the 2017–2018 crop season: the first was based on standard cultivation of the Brazilian Cerrado (without irrigation systems and adequate fertilizer), whereas the second utilized high technology (irrigation systems and increased fertilizer). The morphophysiological parameters, normalized difference vegetation index (NDVI), leaf pigment content and crop yield parameters were evaluated. Our study pointed out the positive responses for both cultivated varieties and two technological levels adopted cultivated under equidistant arrangement and high density. The leaf area index, leaf pigment content, NDVI, and crop production showed substantial responses under different equidistant arrangements. Therefore, this procedure requires adjustments in the level of cultivation technology and identification of the most suitable soybean variety.

The F2 population was developed by crossing the adaptive yield variety of soybean with a variety without the Kunitz trypsin inhibitor in the mature grain. From the segregating F2 population 48 plants were taken. Their seeds were used to set up field experiment; part of the seed was saved for full-sib (FS) crosses. After yield testing, three lines marked as L6, L30 and L38 were chosen. Two FS cross combination, using saved seeds, were made (L30 x L38 and L6 x L30). Progenies of soybean full-sibs (FSF1:2) and each mother plant (F3:4) were grown, to make enough seed for testing in the field experiment. Data obtained in this experiment were processed to determine correlations of grain yield and other studied traits between mother's and proper full-sib progenies, using simple correlations and Spearman's rank correlations. A significant correlation into examinated traits between two types of progenies does not found, except for stem height and 1000 grain weight in the FS combination L30 x L38. The lack of correlation of plant characteristics between progenies of full-sibs and their mothers indicated the influence of lines used as fathers component. In both combinations of FS crosses, FSF1:2 progenies with better yield than the adapted parent (one without Kunitz trypsin inhibitor) were identified, which are considered promising for the further process of creating new varieties.

ABSTRACT Digital aerial images obtained by cameras embedded in remotely piloted aircraft (RPA) have been used to detect and monitor abiotic stresses in soybeans, such as water and nutritional deficiencies. This study aimed to evaluate the ability of vegetation indexes (VIs) from RPA images to remotely detect water and nutritional status in two soybean cultivars for nitrogen. The soybean cultivars BONUS and BRS-8980 were evaluated at the phenological stages R5 and R3 (beginning of seed enlargement), respectively. To do so, plants were subjected to two water regimes (100% ETc and 50% ETc) and two nitrogen (N) supplementation levels (with and without). Thirty-five VIs from multispectral aerial images were evaluated and correlated with stomatal conductance (gs) and leaf N content (NF) measurements. Near-infrared (NIR) spectral band, enhanced vegetation index (EVI), soil-adjusted vegetation index (SAVI), and renormalized difference vegetation index (RDVI) showed linear correlation (p

The objective of this study was to evaluate the performance of four machine learning models, as well as multitask learning, to predict soybean root variables from simpler variables, under two water availability conditions. In order to do so, 100 soybean cultivars were conducted in a greenhouse under a control condition and a stress condition. Aerial part and root variables were evaluated. The machine learning models used to predict complex root variables were artificial neural network (ANN), random forest (RF), extreme gradient boosting (EGBoost) and support vector machine (SVM). A linear model was used for comparison purposes. Multitask learning was employed for ANN and RF. In addition, feature importance was defined using RF and XGBoost algorithms. All the machine learning models performed better than the linear model. In general, SVM had the greatest potential for the prediction of most of the root variables, with better values of RMSE, MAE and R2. Dry weight of the aerial part and root volume exhibited the greatest importance in the predictions. The models developed using multitask learning performed similarly to the ones conventionally developed. Finally, it is concluded that the machine learning models evaluated can be used to predict root variables of soybean from easily measurable variables, such as dry weight of the aerial part and root volume.

ABSTRACT A good soil fertility management for soybean production must consider the amount of nutrients that are exported by seeds. In recent decades, soybean yield has increased due to better crop management and genetic improvements, which may affect the amount of nutrients removed. Therefore, this study aimed (i) to analyze the relationship between the concentration of macronutrients in soybean seeds in Brazil with soybean yield and genotypes, and (ii) to update nutrient concentration values in soybean seeds for fertilizer recommendation purposes, comparing them with the values described in the main official fertilization recommendation systems used in Brazil. For this purpose, we used 3,017 observations obtained from 67 studies evaluating at least one macronutrient concentration [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)] in soybean seeds in the last 45 years in Brazil (from 1974 to 2019). Results indicate that the concentration of macronutrients in soybean seed is affected by both soybean yield and genetic material. Modern genotypes of the Intacta Roundup Ready-2 group remove 15, 21, 18, 17, and 23 % more K, P, Ca, Mg, and S and 4 % less N compared to non-Roundup Ready genotypes. The increase in soybean yield was followed by an increase in the concentration of N and a decrease in the concentration of P and K in soybean seed. Data obtained from studies published between 2015 and 2019 indicates that soybean removes, on average, 57.2, 17.6, 5.5, 2.9, 2.6, and 2.5 kg Mg-1 of N, K, P, S, Ca, and Mg, respectively. These macronutrient concentrations in soybean seeds are in disparity with most reference values described in the official fertilization recommendation systems in Brazil, highlighting an urgent need to review the standard values for replacement fertilization of soybeans. Moreover, future studies should focus on the influence of genetics on soybean seeds composition to ensure high soybean productivity with rational use of fertilizers.

ABSTRACT: In the last crop seasons, the complex of late season diseases (CLSD) of soybean (Glycine max L. (Merrill)), has been causing considerable reductions in the crop yield. Currently, there are no cultivars resistant to all pathogens that causes CLSD. The present study evaluated the effect of applying the acibenzolar-S-methyl resistance inducer, alternative products and fungicide on the severity of CLSD in the soybean cultivar BMX Potência RR during the 2013/2014 and 2014/2015 crops, in the field. The treatments for the experiments were: 1 - control (water); 2 - acibenzolar-S-methyl; 3 - calcium; 4 - micronutrients: copper, manganese and zinc; 5 - micronutrients: manganese, zinc and molybdenum; 6 - nitrogen-potassium fertilizer; 7 - Ascophyllum nodosum and 8 - azoxystrobin + cyproconazole with the addition of the adjuvant. Four applications of alternative products and two of fungicide were carried out in both harvests. A diagrammatic scale assessed the severity of CLSD at the phenological stage R7.1. The acibenzolar-S-methyl resistance inducer, alternative products (macro and micronutrients) and A. nodosum had no effect on the severity of CLSD in the two harvests. The fungicide (azoxystrobin + cyproconazole) reduced the severity of CLSD and prevented damage to productivity in both experiments.

O objetivo desse trabalho foi avaliar o efeito de culturas de entressafra e fertilização com N mineral na implantação da soja sobre os teores de nitrato e amônio no solo durante a entressafra e a safra da soja. O delineamento experimental foi de blocos completos casualizados, com cinco repetições e em esquema de parcelas subdivididas. Nas parcelas foram alocados seis tratamentos de entressafra: pousio, milho segunda safra com 0 ou 80 kg de N ha-1 em cobertura, trigo, braquiária ruziziensis e crotalária spectabilis, sendo as duas últimas destinadas à cobertura do solo. Nas subparcelas foram alocados dois níveis de N na implantação da soja (0 e 30 kg de N ha-1). De abril de 2016 a fevereiro de 2017 foram realizadas 26 coletas de solo na camada de 0,0-0,1 m, sendo avaliados os teores de nitrato e amônio nas amostras. Durante o período de entressafra da soja, os maiores teores de nitrato no solo foram observados no milho segunda safra adubado com 80 kg de N ha-1, enquanto os teores de amônio variaram menos entre os tratamentos de entressafra. As culturas de entressafra não influenciaram os teores de nitrato e amônio no solo durante o ciclo da soja em sucessão. Na fase vegetativa da soja, os teores de nitrato no solo foram superiores quando a soja foi adubada com 30 kg de N ha-1, em relação à ausência de adubação, mas nas fases de formação de vagens e de grãos essa diferença não ocorreu.

Estudos recentes demonstram que a adubação potássica em áreas adeptas do sistema de plantio direto resultam uma boa correlação com a produção de fitomassa de coberturas utilizadas em processo de rotação. O presente trabalho teve como objetivo avaliar os efeitos da adubação potássica em três diferentes gramíneas e a eficácia residual para a cultura da soja em sucessão em sistema de plantio direto. O experimento foi conduzido em área experimental pertencente a UNESP – FEIS, nos anos agrícolas de 2012/13 e 2013/14. O delineamento experimental utilizado foi o de blocos casualizados, sendo os tratamentos quatro doses de K (0, 35, 70, 120 kg ha-1) com quatro repetições. Cada cobertura foi avaliada isoladamente totalizando três subprojetos. O solo da área é classificado como LATOSSOLO VERMELHO Distrófico de textura argilosa. O segundo ano de experimento foi negativamente influenciado pelas questões climáticas problemáticas na época do estudo. Em função dos tratamentos aplicados, maiores produções de fitomassa foram vistas para a sucessão com milho. A maior média para teor de K foliar na soja foi observada em função na sucessão com sorgo. O teor de K na palhada destacou-se para as plantas de milheto. A maior produtividade de grãos de soja foi observada em área de sorgo.

O sistema agroflorestal com eucalipto e soja é uma opção de uso do solo em regiões com solo arenoso e clima quente. O objetivo desse trabalho foi avaliar o desempenho da cultura da soja associada a renques simples de eucalipto maculata (Corymbia maculata) na região Noroeste do Paraná. O sistema agroflorestal foi implantado em outubro de 2009, usando a sucessão soja/ Urochloa ruziziensis nos entre renques simples de eucalipto. O desempenho da cultura da soja foi avaliado na safra 2015/16, em dois experimentos, um com espaçamento entre renques de 14 m e outro com 28 m. Como testemunha, foi considerada uma área contígua, sem a presença de árvores. O crescimento e o acúmulo de nitrogênio na massa seca da soja, avaliados no pleno florescimento, foram reduzidos em função da interferência do eucalipto, com maior intensidade no menor espaçamento entre os renques. A redução de produtividade de grãos de soja causada pelas árvores foi de 65 e 44% em relação à testemunha, nos espaçamentos de 14 e 28 m entre renques, respectivamente. Os teores de nitrogênio na massa seca e de proteína e óleo nos grãos de soja não foram alterados pela interferência das árvores.

ABSTRACT The decision-making capability of the machine to harvest grains must consider a lower fuel consumption with a higher operating velocity allied to a greater performance of the grain cleaning system, along with lower rates of the damage and waste produced. This study aimed at evaluating the operational performance and the energy efficiency of two axial harvesters, having different trail and separation systems in the soybean seed harvest. The experiment was carried out in a completely randomized block design in 500-m bands, consisting of two factors, namely two axial harvesters (single and double rotor) and six target velocities (3, 4, 5, 6, 7, and 8 km h-1). Regarding the operational energy performance, the hourly fuel consumption, operational speed, operational field capacity, fuel consumption per area and mass of the harvested grain, and the handling capacity of the harvest were evaluated. The harvesting performance parameters, such as the percentage losses in the platform and the trail system, broken grains, impurities, and the pods, which did not undergo threshing, were evaluated. The results obtained showed that the single-rotor harvester had a better energy efficiency, while the double-rotor harvester had a better operational performance. The double-rotor harvester was agronomically more efficient.

ABSTRACT: Successive cycles of water absorption and loss favor weathering deterioration, one of the main factors that affect the quality of soybean seeds. This study evaluated the physiological, physical, and morpho-anatomical changes in soybean seeds under weathering deterioration at the pre-harvest phase. Six soybean cultivars (BMX Apolo, DM 6563, NS 5959, NA 5909, BMX Potência, and TMG 1175) were produced in a greenhouse and underwent weathering deterioration through a rainfall simulation system, applying 0, 60, 120, and 180 mm of precipitation at pre-harvest phase. Each rainfall level was divided into two applications at an interval of 72 h: 60 mm (30 + 30), 120 mm (60 + 60), and 180 mm (90 + 90). After harvest, the seeds were evaluated for germination, vigor, physical and morpho-anatomical properties. Weathering deterioration induced by simulated rainfall at the pre-harvest phase contributes to the reduction in soybean seed germination and vigor and is conditioned by the soybean genotype. The increase in intensity of simulated rainfall led to a more significant weathering damage in seeds, as evidenced by the X-ray and tetrazolium test. Cultivars DM 6563 and BMX Potência were more susceptible, while NA 5909 was less susceptible to weathering deterioration (especially at the highest level; 120 mm and 180 mm). Anatomical changes caused by weathering deterioration lead to cell compaction and rupture, mainly in the cell layers of the hourglass and parenchyma, forming intracellular spaces. The presence of weathering damage caused a reduction in physiological soybean seed quality.

The nutritional value of Glycine max L. (soybean) and its yield potential for improving sustainability of agricultural systems has resulted into its increased production. Soybean crop has potential to replace the rice crop in the rice-wheat cropping system. However, the crop has shown high sensitivity towards iron (Fe) deficiency, and thus recorded major yield and nutritional quality losses. Thus, a three-year field experiment was planned to compare the impact of the application rate (0.5% and 1.0%) and number of sprays of FeSO4 on yield, Fe nutrition, and economic outcomes of soybeans. The Fe application posed a beneficial impact on the studied parameters due to an increase in enzymatic activity of Fe-containing enzymes. Among various treatments, maximum increase in grain and straw yield (3064 and 9341 kg ha−1, respectively) was obtained with 0.5% FeSO4 application at 30, 60, and 90 DAS over the control (2397 and 6894 kg ha−1, respectively). Similar results were attained for grain Fe concentration (69.9 mg kg−1) and Fe uptake in grain and straw (214 and 9088 g ha−1, respectively). The results were statistically non-significant, with the treatment in which 0.5% FeSO4 was applied at 30 and 60 DAS. The economic returns of soybean cultivation were also highest with 0.5% FeSO4 application at 30, 60, and 90 DAS with highest benefit; the cost (3.02) followed by treatment in which 0.5% FeSO4 was applied at 30 and 60 DAS. Thus, 0.5% FeSO4 application at 30, 60, and 90 DAS can be recommended for soybeans grown on sandy loam soil followed by 0.5% FeSO4 application at 30and 60 DAS to harness maximum yield, Fe concentration, and profitability.

O sucesso da cultura da soja depende da qualidade fisiológica das sementes, a qual pode ser favorecida por microrganismos benéficos, mas prejudicada por fatores ambientais desfavoráveis. O objetivo desse estudo foi avaliar o efeito da coinoculação com Bradyrhizobium japonicum e Azospirillum brasilense na qualidade fisiológica de sementes de soja obtidas na safra 2017/2018, em ensaio de campo com 23 cultivares, submetidas à coinoculação via sulco de semeadura ou mantidas sem coinoculação. As plantas foram avaliadas quanto à nodulação em R1 e, após a colheita (R8), determinaram-se os teores de proteínas, massa de mil sementes e a qualidade fisiológica das sementes [Germinação, emergência em areia e índice de velocidade de emergência (IVE)]. Na média das cultivares, o número de nódulos aumentou de 36,9 no controle para 44,4 nódulos por planta com a coinoculação. Os aumentos nos teores de proteínas e na massa de mil sementes devido à coinoculação foram de 5,6% e 34,7%, respectivamente. As sementes das plantas coinoculadas apresentaram maior germinação na primeira contagem (50,0% vs. 45,3%) e na final (87,0% vs. 79,8%), além de maior taxa de emergência de plântulas em caixa de areia (83,3% vs. 80,0%) e maior IVE (18,5 vs. 17,4). Os benefícios da coinoculação foram observados em 17 das 23 das cultivares (74%), em pelo menos duas das sete variáveis avaliadas. Considerando apenas o critério de germinação mínima de 80%, as sementes de 10 cultivares não inoculadas não serviriam para uso, enquanto que para as coinoculadas esse número caiu para quatro.

O manejo de plantas daninhas na cultura da soja, através da redução do espaçamento de plantio, figura-se como importante fator de cultivo ao qual depende o sucesso da produção. O objetivo desse estudo foi avaliar as composições florística, ecológica e fitossociológica de plantas daninhas no cultivo da soja sob diferentes espaçamentos em uma área de savana amazônica, em Boa Vista, RR, Brasil. A cultivar BRS 7980 foi semeada em sistema convencional, em quatro blocos com três diferentes espaçamentos (45, 55 e 65 cm) entre fileiras. A amostragem de plantas daninhas foi realizada através de um quadrado de ferro (0,25 m2), o qual foi arremessado aleatoriamente quatro vezes em cada bloco, totalizando 4,0 m2 de área amostrada. Um total de 16 espécies de plantas daninhas foram registradas, distribuídas em dez gêneros e cinco famílias, das quais predominaram Fabaceae e Malvaceae. Quatro espécies estiveram presentes em todos os espaçamentos: Mimosa pudica L., Urochloa decumbens Stapf., Calopogonium muconoides Desv. e Waltheria communis A.St.-Hil. Os diferentes espaçamentos não foram indicadores da composição florística de plantas daninhas. O baixo índice de similaridade entre as espécies indicou que a comunidade de plantas foi afetada pelos diferentes espaçamentos utilizados. Urochloa decumbens Stapf. obteve maior destaque nos parâmetros fitossociológicos avaliados, necessitando de atenção especial no controle. A maior massa seca de plantas daninhas foi obtida nos espaçamentos de 55 e 65 cm. O tipo de propagação, a forma de vida e o ciclo de vida predominantes foram por sementes, erva e perene, respectivamente. A rota fotossintética predominante foi do tipo C3, especialmente em 45 cm. Portanto, o cultivo de soja em espaçamento de 45 cm entre fileiras ocasiona redução da composição ecológica e fitossociológica de plantas daninhas em área de savana amazônica. Os diferentes espaçamentos entre fileiras não são indicadores da composição florística de plantas daninhas no cultivo da soja em savana amazônica.

O objetivo do trabalho foi avaliar o efeito dos produtos acibenzolar-s-metil, fosfito de potássio, silicato de potássio e trifloxistrobina + protioconazole no controle curativo do oídio (Microsphaera diffusa) na soja. O delineamento experimental foi inteiramente casualizado, em esquema unifatorial, contendo cinco tratamentos com quatro repetições. A aplicação dos produtos foi realizada no estádio fenológico V4, no qual as plantas possuíam 5% de severidade da doença. Aos 7, 14 e 21 dias após aplicação dos tratamentos (DAA), foi avaliada a incidência e severidade da doença. O trifloxistrobina + protioconazole reduziu a incidência em 30% e a severidade em 80%, quando comparado ao controle. Também foi avaliado o efeito inibitório dos produtos na produção de conídios in vivo e na sua germinação in vitro. O trifloxistrobina + protioconazole proporcionou a maior redução na produção de conídios e na inibição da germinação. O acibenzolar-s-metil, fosfito de potássio e silicato de potássio também reduziram a germinação de conídios, mas não afetaram a produção. Com base nisso, conclui-se que, o fungicida trifloxistrobina + protioconazole reduziu a produção de conídios e inibiu sua germinação, apresentando efeito curativo e protetor contra oídio em soja e que os indutores de resistência testados, interferem na germinação do patógeno, mas sem efeito significativo na doença quando aplicados após o surgimento dos sintomas.

The spatial variability of soil physical attributes is important to indicate management practices that best suit agricultural areas. This study aimed to analyze spatial correlations between soybean grain yield and soil mass-volume relationships, in order to select which attribute is correlated with yield, as well as to evaluate the spatial variability of soil attributes and yield components of this crop, in an Oxisol under no-tillage system. The soil attributes analyzed (0.0-0.10 m and 0.10-0.20 m) were the following ones: soil bulk density (paraffin-coated clod and volumetric ring methods), particle density (volumetric flask and modified volumetric flask methods) and total porosity. The soybean yield components were evaluated as it follows: grain yield, number of pods per plant, number of grains per pod, mass of 100 grains, grain mass per plant, plant population and plant height. The total soil porosity, calculated by the relations between the bulk density (volumetric ring method) and particle density (volumetric flask), in the 0.10-0.20 m layer, was the best indicator of soybean grain yield under no-tillage conditions.

A densidade de semeadura e o espaçamento entre as fileiras podem influenciar no crescimento e desenvolvimento das culturas. O objetivo do trabalho foi avaliar a dinâmica do crescimento de duas cultivares de soja com tipo de crescimento indeterminado, em diferentes arranjos espaciais de plantas, compostos por espaçamentos entre fileiras e densidades de semeadura. O experimento foi conduzido nas safras 2013/14 e 2014/15 com delineamento experimental em blocos completos casualizados, esquema fatorial 2 x 4 x 3, com três repetições. Os tratamentos constituíram-se da combinação de duas cultivares: BRS 359 RR e BMX Potência RR, de quatro espaçamentos entre fileiras: 20 cm (reduzido); 20/80 cm (fileira dupla); 50 cm (usual) e 50 x 50 cm (cruzado) e três densidades de semeadura: 150, 300 e 450 mil sementes viáveis ha-1. Foram avaliados o índice de vegetação por diferença normalizada (NDVI) e a porcentagem da cobertura do solo pelo dossel. O NDVI e a porcentagem de cobertura do solo pelo dossel de cultivares modernas de soja, com tipo de crescimento indeterminado, são mais afetados pelos espaçamentos entre fileiras no início do ciclo de desenvolvimento, mas na fase de enchimento de grãos as diferenças são menores. A densidade de 150 mil sementes viáveis ha-1 ocasiona menor NDVI e cobertura do dossel no início do ciclo, entretanto no final do ciclo essa diferença se dissipa e todas as densidades apresentam pleno fechamento do dossel.

The spatial arrangement of soybean plants, determined by row spacing and seeding rate, affects the intraspecific competition for water, light, and nutrients, as well as plant architecture and grain development, quality, and chemical composition. The aims of this study were to evaluate the effect of row spacing and seeding rate on the grain size produced, and the influence of these three factors on chlorophyll retention and protein and oil content in grain. Two experiments were conducted in the 2013/14 and 2014/15 growing seasons, using a 4 × 3 factorial randomized block design with three replications. Four different row spacings [20 cm (narrow row), 50 cm (conventional), 20/80 cm (twin rows) and crossed lines (50 cm)] and three seeding rates (150, 300, and 450 thousand viable seeds ha-1) were evaluated. The grains were classified by size using oblong sieves and then the effects of spatial arrangements and size of grain on the percentage of green grains and protein and oil contents were evaluated. Higher plant densities were associated with larger grain size, whereas the effects of spacing between the rows on the grain size varied between growing seasons. The arrangement in cross-rows and high plant density produced a higher percentage of green grains under weather conditions favorable to the development of this attribute. The effects of plant spatial arrangements on the contents of protein and oil in grains were variable, and it was not possible to determine whether the spatial arrangement of plants had an effect on the levels of protein and oil in grains. Larger grains had higher protein content, but oil contents were not affected by grain size.

Drought stress is a limitation for the agricultural production, having as a primary effect the reduction of plant gas exchanges, and the continuity of its incidence results in a lower yield. This study aimed to evaluate the photosynthetic responses and the soybean yield, concerning the seed inoculation and foliar spray with Azospirillum brasilense and plant regulator containing auxin, gibberellin and cytokinin. A randomized complete block design was used under greenhouse conditions, with five treatments: four under drought stress (control, seed inoculation and foliar spray with A. brasilense and plant regulator) and one irrigated treatment. The soil gravimetric moisture, relative water content, CO2 net assimilation rate, apparent quantum efficiency, light compensation point and grain yield were evaluated. The water deficiency reduced the relative water content by 76.96 % and the soybean gas exchanges by 860.43 %, in the drought stress control. However, when using A. brasilense or plant regulator, the reduction of these values was mitigated, with maximum reductions of 52.40 % in the relative water content and 361.99 % in the gas exchanges. Thus, the mitigation of these effects was directly correlated with the grains yielded by plants, where the use of foliar spray with A. brasilense or plant regulator presented averages 19 % higher than the drought stress control. The applications of foliar spray with A. brasilense and plant regulator mitigate the effects of drought stress on the soybean photosynthesis and culminate in lower yield losses.

ABSTRACT: The presence of a compacted soil layer near the ground surface in paddy fields may limit the growth and development of soybean roots. The objective of this study was to evaluate different planting management systems and irrigation on growth and development of soybean root systems in lowland area. The experiment was carried out in 2013/14 and 2014/15 crop seasons in randomized complete block design with factorial treatment (3x2), with four replications. The treatments consisted of different planting management systems: sowing with double disc (A1); sowing with shank (A2) and deep tillage + sowing with double disc (A3), and irrigation: irrigated (D1) and non irrigated (D2). Planting management systems and irrigation influenced the growth of soybean roots. When double disc was used, roots have lower growth and increase in diameter. Use of shanks and deep tillage provide increased growth and development of soybean roots and greater depth distribution. An additional 55mm of irrigation during the V4 soybean development stage provides increased surface area and root volume in when the soil moisture reaches values below 60% of field capacity.

Drying agricultural products reduces the moisture content to suitable levels for storage, in order to maintain the product quality. However, special care with the temperatures applied in the process is important for the integrity and longevity of the material. The present study aimed at determining the immediate and latent effect of air-drying temperatures on the quality of soybean produced as a second season crop. The grains were collected at the R8 stage, close to the physiological maturity, with moisture content of approximately 23 % (w.b.), submitted to drying temperatures of 40 ºC, 50 ºC, 60 ºC, 70 ºC and 80 ºC, up to a moisture content of 12.5 ± 0.7 % (w.b.), and then stored under non-controlled humidity and temperature for 180 days. Thereafter, quality was assessed every 45 days by determining the dry matter loss, color and crude protein and lipid contents, as well as the acidity and peroxide indices of the crude oil extracted. Based on the results obtained, it was concluded that the increase in the air-drying temperature affects the soybean quality and crude oil extracted, being this effect enhanced with the storage time; the soybean and crude oil quality decline with an increase in the air-drying temperature and storage time; the air temperature of 40 ºC has the least effect on the quality of soybean grains and crude oil extracted.

The use of modeling is a trend for agronomic science that aims to detect factors that could limit the growing practices and influence the potential yield of some crops. The objective of this study was to calculate the accumulated thermal time and estimate the phenological stages length of three soybean cultivars in two crop years, using agronomic models associated to meteorological variables. Two experiments were conducted in a field at the Agroclimatology Laboratory (LAGRO) of the Federal University of Santa Maria/UFSM, campus of Frederico Westphalen/RS, Brazil during the 2012/2013 and 2013/2014 crop years. A randomized block in a factorial scheme 6x3 with six spatial arrangements (45, crossed, 20, 20x40, 20x60 and 20x80 cm) and three cultivars with different cycles and growth habits (BMX Ativa RR/determinate, BMX Turbo RR/indeterminate and BMX Potência RR/indeterminate) with three replications were used for the experimental design. Sowing was held on 11/28/2012 and 12/02/2013. The assessed phenological stages were sowing-emergence; emergence – final vegetative; final vegetative – full bloom; full bloom – physiological maturity. The duration of each stage was related to meteorological parameters: maximum temperature, minimum temperature, average temperature, rainfall, solar radiation, and thermal time. Air temperature influences soybean growth and development. The accumulated thermal time varies between years and among cultivars, and it is the main contributor to the estimated duration of the phenological stages.

Despite the technology available to agriculture, qualitative and quantitative losses occurring during post-harvest are still not controlled, and stored grains may undergo changes in their composition, due to storage conditions. This study aimed at determining the sensitivity of the alcoholic acidity and pH tests in soybean (GB 874RR cultivar) grains with different quality standards obtained during storage. A completely randomized design, in a 3 x 6 x 5 (3 storage conditions x 6 storage times x 5 methods) factorial scheme, was used. A correlation was observed among pH, total acidity content (r = 0.888) and grain quality parameters. Deterioration was identified based on the total acidity content, showing a high correlation with fungal incidence (r = 0.864), ether extract (r = -0.781) and electrical conductivity (r = 0.923). The use of phenolphthalein as indicator is more sensitive than pH 8.8. Among the pH determination methods, AOAC was the most suitable for assessing the quality loss during storage.

The frogeye leaf spot, a disease caused by the fungus Cercospora sojina, affects soybean crops worldwide with enormous economic impact. In this study, we evaluated the combined effects of temperature and duration of leaf wetness periods on the intensity of frogeye leaf spot in soybean. Experiments were conducted in a growth chamber with cultivar Don Mario 7.0i at temperatures of 15, 20, 25, 30 and 35°C and leaf wetness periods of 12, 24, 36, 48 and 72 hours. The experimental design was completely randomized with five replications. When soybean plants were grown at 15°C, affected leaflet area, number of lesions per leaflet and diameter of lesions could only be measured after 60 hours of leaf wetness. At the temperatures of 20 and 25°C this period was reduced to 24 hours of leaf wetness, at 30oC, we found the need for 36 hours of leaf wetness and at a temperature of 35°C, 48 hours. The optimal temperatures for disease development were 27°C for diameter and affected leaflet area and 28°C for number of lesions per leaflet with 72 hours of leaf wetness.

Sistemas agroflorestais são opções para a intensificação sustentável da produção agropecuária, sobretudo em regiões que apresentam clima tropical e solos arenosos. Objetivou-se nesse trabalho avaliar o desempenho da cultura da soja em sistemas agroflorestais com Eucalyptus urograndis na região Noroeste do Paraná. Os sistemas foram implantados em outubro de 2009, usando renques simples e duplos de eucalipto. O desempenho da cultura da soja foi avaliado na safra 2015/16, em quatro experimentos. Em cada experimento foi utilizada uma conformação espacial de plantas de eucalipto: renques simples com baixa densidade de árvores, renques simples com alta densidade, renques duplos com baixa densidade e renques duplos com alta densidade. Como testemunha, foi considerada uma área contígua, sem a presença de árvores. Nos quatro experimentos, o crescimento e o teor de nitrogênio na massa seca da soja, avaliados no pleno florescimento, não foram reduzidos expressivamente em função da interferência do eucalipto. A redução de produtividade de grãos de soja causada pelas árvores variou de 40 a 43% em relação à testemunha. Os teores de proteína e óleo nos grãos de soja não foram alterados pela interferência das árvores.

A densidade de semeadura na cultura da soja provoca diversas modificações morfofisiológicas nas plantas, podendo alterar o crescimento e a produtividade de grãos. Objetivou-se avaliar o efeito de densidades de plantas de soja sobre o índice de área foliar (IAF) e índice SPAD (Soil Plant Analysis Development) durante o ciclo de desenvolvimento da cultura, correlacionando esses dados com a produtividade de grãos. O experimento foi conduzido na safra 2015/16, na área experimental da Embrapa Soja, Londrina, PR, em delineamento experimental de blocos completos casualizados, com cinco repetições. Foram avaliadas as densidades de 120, 230, 340 e 380 mil plantas aptas ha-1, em espaçamento de 0,45 m entre fileiras, utilizando a cultivar BRS 359 RR, que apresenta tipo de crescimento indeterminado e arquitetura compacta de plantas. Constatou-se que o aumento da densidade de plantas de soja incrementa o IAF até o estádio R3, mas, após essa fase, o IAF não varia entre as densidades. A densidade de plantas de soja não altera o índice SPAD até o estádio R5.4. Durante o crescimento vegetativo não há correlação entre o IAF e o índice SPAD com a produtividade de grãos, porém na fase de enchimento de grãos há correlações positivas entre essas variáveis.

ABSTRACT: This study was aimed at assessing some biological parameters of Bemisia tabaci B biotype at immature stages to examine antibiosis in six soybean genotypes, besides antixenosis resistance to oviposition in choice and non-choice tests, under greenhouse and laboratory conditions. Between April 2016 and August 2016, bioassays were carried out at the Laboratory of Applied Entomology at College of Agricultural Sciences at Federal University of Grande Dourados (UFGD) Dourados (MS), Brazil. The following variables were evaluated: egg incubation period, nymphal and egg-to-adult duration, egg and nymph viability, and egg-to-adult survival on the soybean genotypes 68i70 RSF IPRO, M6210 IPRO, MS 947 IPRO, BMX Potência RR, M6410 IPRO, and ANTA 82 RR. Antixenosis resistance to oviposition by the silverleaf whitefly was found for MS 947 IPRO, while oviposition was highest for ANTA 82 RR, M6210 IPRO, and M6410 IPRO. The genotype MS 947 IPRO adversely affected egg and nymph viability, and egg-to-adult survival rates was the lowest among genotypes (59.75%), suggesting antibiosis resistance to this pest.

ABSTRACT: In the last few cropping seasons, some soybean producers have tested the application of a hill drop sowing method, usually from three to four seeds every 30 to 40cm. However, there is a lack of information in the literature about the effect of this practice on soybean performance. Thus, the objective of this study was to evaluate the effect of a hill drop sowing with different number of plants per hole on soybean performance. The study was conducted in Londrina - PR, Brazil, during the 2013/14, 2014/15 and 2016/17 cropping seasons. The experiment was a randomized complete block design with four replications and a 2x5 factorial scheme. The first factor consisted of two soybean cultivars, BRS 359RR and NK 7059RR analyzed in the first two cropping seasons and BRS 359RR and BRS 1010IPRO in the last cropping season. The second factor was constituted by five in-hill hole-spacing treatments (HS) (8, 16, 24, 32 and 40cm), with rows spaced 50cm apart. To maintain the same plant density in all treatments (270,000 plants ha-1), sowing was performed manually, being then thinned out. After thinning, the distribution was one plant per hole at HS8, 2 plants at HS16, 3 plants at HS24, 4 plants at HS32, and 5 plants at HS40. The agronomic performance of soybean in hill drop sowing with different number of plants per hole is similar to that of an equidistant distribution of plants.

A cultura da soja apresenta alta plasticidade fenotípica da parte aérea, alterando a sua morfologia em função da densidade de plantas. No entanto, os seus efeitos no crescimento e na distribuição de raízes no perfil do solo ainda não estão elucidados. O objetivo do presente trabalho foi avaliar o efeito de três densidades de plantas de soja sobre variáveis relacionadas ao crescimento de raízes, em diferentes camadas de solo e posições (linha e entrelinhas). Foram conduzidos dois experimentos na safra 2014/2015 em Londrina, PR, um com a cultivar BRS 359 RR e outro com a cultivar BMX Potência RR. O delineamento experimental foi de blocos casualizados, com três repetições e parcelas subsubdivididas. Nas parcelas principais, foram alocadas três densidades de semeadura (150, 300 e 450 mil sementes ha-1); nas subparcelas, cinco camadas de solo (0-10, 10-20, 20-30, 30-40 e 40-50 cm); e nas subsubparcelas, três posições (linha, entrelinha à esquerda e entrelinha à direita). O aumento da densidade de plantas provoca a formação de raízes mais finas, com tendência de haver maior ocupação das entrelinhas e das camadas subsuperficiais do solo, mas a magnitude dessa resposta é dependente da cultivar.

The spatial arrangement of soybean plants affects the intraspecific competition for light, water and nutrients, which can change the biomass production, incidence of pests, diseases and weeds, plant lodging, and grain yield. This work aimed to evaluate the agronomic performance under different row spacing, plant densities and crossed rows. Two field experiments were carried out in Campo Mourão, Paraná State, Southern Brazil, using the randomized complete block experimental design, in a 3x3x2 factorial arrangement, with four replications. The treatments were formed by the combination of three row spacings (0.30, 0.45, and 0.60 m), three plant densities (300,000; 450,000; and 600,000 plants ha-1), and two row design (crossed or parallel rows). For all variables, interaction of the experimental factors was not significant. The row spacing of 0.45 m provided the highest grain yield in relation to 0.30 and 0.60 m. The density of 300,000 plants ha-1 showed higher yield of soybeans in late sowing. The crossed lines did not increase the productive performance in soybean.

The climate, particularly water availability, presents itself as a limiting factor to obtain yields close to the productive potential of crops, being the major cause of interannual variability in grain production and income in different regions of Brazil. In this context, this study aims to identify and characterize the effect of water stress on the yield of soybean crops, maize and beans and on the costs, gross income and profit from these in the region of Santiago, RS. Therefore, we used the calibrated DSSAT system and validated for the conditions and cultures being studied, and used the historical period 1961-2010 to generate production data for each crop. Data were adimensionalizados building on the potential production of each culture, establishing frequency histogram for assessing the risk of production loss in respect of each crop. Later they used historical data series costs and selling prices of crops in the same study period for performing simplified economic analysis. In terms of production, bean, corn and soybeans in 65%, 50% and 41% of the years, respectively, achieved yields below 50% of the potential of these crops. In economic terms, the biggest cost; gross income and average income are associated with corn, followed by the bean crop and soybean, respectively. The three crops, soybean, corn, beans, showed significant reductions in production and consequently profit depending on water restriction.

O objetivo do trabalho foi caracterizar o metabolismo primário, com ênfase na atividade fotossintética, de plantas de soja sob diferente disponibilidade hídrica. O experimento foi conduzido em câmara de crescimento com plantas jovens de soja cv. BMX Apolo RR, cultivadas sem restrição hídrica até o estádio de seis folhas trifolioladas expandidas e a sétima folha aberta.Foram estudados cinco níveis de disponibilidade hídrica(-0,004, -0,006, -0,026, -0,042 e -0,164MPa) com oito vasos (repetições) por tratamento. Avaliou-se a assimilação líquida de carbono (AL), condutância estomática (gs) e transpiração (E) na sexta folha de uma planta de cada vaso. Foi determinado o potencial da água na folha, fluorescência da clorofila,conteúdo de clorofila (a, b e total), rendimento quântico e caracterizado o crescimento vegetativo. Potenciais da água no solo de -0,026 MPa comprometem a assimilação líquida de carbono de plantas de soja em função da redução da condutância estomática. Os potenciais aplicados não influenciam na quantidade de pigmentos fotossintéticos e no crescimento vegetativo em situações de breve exposição ao estresse.

The presence of animals in farming areas can affect soil physical structures depending on grazing intensity. This study aimed to evaluate soil physical attributes, as well as soybean and brachiaria yield, under no-tillage, in an integrated crop-livestock system. Treatments were arranged in a complete randomized blocks design, with three replications, and consisted of different grazing heights (0.25 m, 0.35 m and 0.45 m) and a no-grazing area. The shoot and root dry biomass of soybean and brachiaria and soybean yield were evaluated. Soil samples were collected from 0-5 cm, 5-10 cm and 10-20 cm depth layers and the following soil physical attributes were determined: bulk density, total porosity, macroporosity, microporosity, penetration resistance and mean weight diameter of aggregates. Grazing intensities did not affect soil bulk density in any of the analyzed layers. There was a reduction in total porosity after the second grazing cycle, in the 0-5 cm layer. The mean weight diameter of aggregates was lower in grazed areas, in the 0-5 cm and 10-20 cm layers, and an increase in the penetration mechanical resistance was observed in all layers, especially for the 0.25 m height grazing treatment. The total dry biomass (soybean + brachiaria) and shoot dry biomass of brachiaria were lower in grazed areas. However, the soybean yield was not affected by the different grazing cycles.

Among studies focused on increasing soybean grain yield, the ones related to sowing process are the most significant. Considering that soybean has an epigeal emergence, it becomes difficult to hint at the length covered by hypocotyl up to soil surface, or the actual planting depth. This study aimed to find an indicator that allows the identification of an ideal soybean planting depth. For this purpose, two complementary assays has been carried out in a greenhouse. The first aimed to identify structures that could be indicators of seed planting depth, on a medium-textured soil from Campos Gerais region, in the state of Paraná, Brazil. Spring NK 8350 cultivar seeds were sown at five theoretical depths (1, 2, 3, 4 and 5 cm). As seedlings emerged, the “differentiation zone” and the “root curve” depths were measured. The second assay was the validation of the suggested indicators in assay 1 from two soils, one medium-textured and one clay-textured. For this assay, it was used BRS 232. Both the methodologies showed high correlation with the theoretical planting depth. Although their correlation coefficient values were close, the differentiation zone appeared to be the most efficient reference with less planting depth overestimation.

A secagem é um dos fatores preponderantes à preservação da qualidade dos grãos. No entanto, se realizada de maneira inadequada, pode reduzir drasticamente a qualidade dos grãos. Da percepção qualitativa, a transferência massa/calor propicia alterações no teor de água, de matéria seca, tamanho e qualidade fisiológica. Objetivou-se com este estudo verificar a influência da taxa de remoção de água sobre a qualidade fisiológica dos grãos de soja. O experimento foi conduzido no delineamento inteiramente casualizado, em esquema fatorial 2 x 8 (duas temperaturas de secagem e oito teores de água), cinco repetições. Na redução do teor de água de 28 ±0,2% em base seca (bs) à umidade de armazenamento 12±0,2% (bs), utilizaram-se temperaturas do ar de 45 e 50ºC, cuja massa foi pesada periodicamente no processo de secagem, separando-se frações de grãos nos teores de água (28, 25, 22, 20, 18, 16, 14, 12%) para cada repetição, avaliando-se velocidade de secagem e potencial fisiológico, para cada temperatura. Os efeitos imediatos e latentes da temperatura de secagem sobre a qualidade dos grãos revelaram que a incidência de alterações é função da velocidade de secagem, cuja temperatura de 50°C propiciou reduções expressivas no potencial fisiológico dos grãos. Enquanto a temperatura de secagem não teve efeito sobre a cor do grão, o teor de água do grão apresentou relação direta com o volume, o peso e a matéria mineral, e relação inversa com o teor de carboidratos, proteínas, lipídios e massa específica do grão. O teste de condutividade elétrica não identificou danos aos grãos e pelo envelhecimento acelerado, detectou-se o efeito do teor de água e da temperatura de secagem sobre a qualidade do grão.

A secagem é um dos fatores preponderantes à preservação da qualidade dos grãos. No entanto, se realizada de maneira inadequada, pode reduzir drasticamente a qualidade dos grãos. Da percepção qualitativa, a transferência massa/calor propicia alterações no teor de água, de matéria seca, tamanho e qualidade fisiológica. Objetivou-se com este estudo verificar a influência da taxa de remoção de água sobre a qualidade fisiológica dos grãos de soja. O experimento foi conduzido no delineamento inteiramente casualizado, em esquema fatorial 2 x 8 (duas temperaturas de secagem e oito teores de água), cinco repetições. Na redução do teor de água de 28 ±0,2% em base seca (bs) à umidade de armazenamento 12±0,2% (bs), utilizaram-se temperaturas do ar de 45 e 50ºC, cuja massa foi pesada periodicamente no processo de secagem, separando-se frações de grãos nos teores de água (28, 25, 22, 20, 18, 16, 14, 12%) para cada repetição, avaliando-se velocidade de secagem e potencial fisiológico, para cada temperatura. Os efeitos imediatos e latentes da temperatura de secagem sobre a qualidade dos grãos revelaram que a incidência de alterações é função da velocidade de secagem, cuja temperatura de 50°C propiciou reduções expressivas no potencial fisiológico dos grãos. Enquanto a temperatura de secagem não teve efeito sobre a cor do grão, o teor de água do grão apresentou relação direta com o volume, o peso e a matéria mineral, e relação inversa com o teor de carboidratos, proteínas, lipídios e massa específica do grão. O teste de condutividade elétrica não identificou danos aos grãos e pelo envelhecimento acelerado, detectou-se o efeito do teor de água e da temperatura de secagem sobre a qualidade do grão.

ABSTRACT: This study investigated the effects of soil management systems, tillage, and application of gypsum agricultural to soil, on soybean development in lowland areas. The experiment was carried out on an Alfisol in a randomized complete block design in a factorial arrangement. The two soil tillage practices were without deep tillage and with deep tillage. Gypsum treatments were no gypsum application, 500kg of gypsum ha-1, 1000kg of gypsum ha-1, and 1500kg of gypsum ha-1. Deep tillage resulted in less soil resistance to root penetration during ryegrass cultivation during the soybean offseason, 11 months after applying the management treatments, resulting in higher dry mass of ryegrass in the offseason and higher soybean yield in the following year.

Heavy metals can accumulate in soil and cause phytotoxicity in plants with some specific symptoms. The present study evaluated the specific symptoms on rice and soybeans plants caused by excess of heavy metals in soil. Rice and soybean were grown in pots containing soil with different levels of heavy metals. A completely randomized design was used, with four replications, using two crop species and seven sample soils with different contamination levels. Rice and soybean exhibited different responses to the high concentrations of heavy metals in the soil. Rice plants accumulated higher Cu, Mn, Pb and Zn concentrations and were more sensitive to high concentrations of these elements in the soil, absorbing them more easily compared to the soybean plants. However, high available Zn concentrations in the soil caused phytotoxicity symptoms in rice and soybean, mainly chlorosis and inhibited plant growth. Further, high Zn concentrations in the soil reduced the Fe concentration in the shoots of soybean and rice plants to levels considered deficient.

Heavy metals can accumulate in soil and cause phytotoxicity in plants with some specific symptoms. The present study evaluated the specific symptoms on rice and soybeans plants caused by excess of heavy metals in soil. Rice and soybean were grown in pots containing soil with different levels of heavy metals. A completely randomized design was used, with four replications, using two crop species and seven sample soils with different contamination levels. Rice and soybean exhibited different responses to the high concentrations of heavy metals in the soil. Rice plants accumulated higher Cu, Mn, Pb and Zn concentrations and were more sensitive to high concentrations of these elements in the soil, absorbing them more easily compared to the soybean plants. However, high available Zn concentrations in the soil caused phytotoxicity symptoms in rice and soybean, mainly chlorosis and inhibited plant growth. Further, high Zn concentrations in the soil reduced the Fe concentration in the shoots of soybean and rice plants to levels considered deficient.

New discoveries have stimulated the use of different substances with physiologic effects, in order to develop agricultural crops. Thus, this study aimed at evaluating seeds treated with biostimulant, bioactivator and nutrients, in the initial development of soybean seeds. Two lots of seeds (high and low vigor, BMX Potência RR cultivar) were used. The products tested were an insecticide with bioactivator effect, a plant growth regulator with biostimulant effect, a complex of nutrients and a control. Under laboratory conditions, the parameters water content, germination, first germination counting, accelerated aging, cold test, length and dry matter weight of seedlings were evaluated. Under greenhouse conditions, evaluations included emergence, emergence speed index, length and dry matter weight of seedlings. The efficiency of the products tested was affected by the seed physiologic quality, with a more pronounced effect for the products in high vigor lots. In general, the treatment with best results for initial performance was the complex of nutrients, followed by the plant growth regulator with biostimulant effect. The bioactivator had negative effect on seeds germination and seedling development.

The integrated crop- livestock-forest system can enhance the production of soybeans, meat and wood in regions characterized by sandy soils and warm climate. The aim of this study was to evaluate the yield of soybean, Urochloa ruziziensis grass and eucalyptus in an integrated system during the first four years after the establishment of eucalyptus in the northwestern region of Paraná state, Brazil. The experiment was established in October 2009, using soybean (summer) -U. ruziziensis (autumn/winter) succession between single rows of Corymbia maculata (eucalyptus species). The spacing between tree rows and eucalyptus plants in the row were 14 and 4.2 m, respectively. Adjacent plots had the same soybean-U. ruziziensis succession, but without eucalyptus. The spatial variability of soybean grain yields and grass shoot dry matter production was evaluated with and without trees, and the data was analyzed using geostatistics, with the results expressed as spatial variability maps. The tree component did not significantly affect soybean yield in the first two growing seasons. In the 3rd and 4th growing season (2011/12 and 2012/13), the interference of eucalyptus reduced the soybean grain yield by 2.9 and 27.0%, respectively, and the effect was stronger close to the tree rows. In July 2012, the tree component reduced the shoot dry matter productivity of U. ruziziensis by 29.2%. At 19 and 35 months after eucalyptus planting, the cumulative wood volume production was 0.73 and 5.17 m³ ha-1, respectively.