ABSTRACT Integrated crop-livestock system (ICLS) can help improve the soil physical attributes, increasing the nutrients cycling and yield potential. We evaluated the effect of forage height management under ICLS on physical soil attributes and water infiltration. Field experiment was carried out for two consecutive years in a randomized complete block design, with three repetitions. Forage was managed under continuous grazing, grazing up to 30 cm (G30), 20 cm (G20) and 10 cm (G10) of height, and control without grazing. Soil bulk density (SBD), microporosity (MIP), macroporosity (MAP), and total porosity (TP) were measured before and after the grazing at 0-5; 5-10 and 10-20 cm layer depth. Water infiltration rate was evaluated using the concentric rings in eight periods (5, 10, 15, 20, 30, 60, 90 e 120 min after beginning of the process). SBD at 0-5 cm layer was not affected by the grazing management, whereas the MIP, MAP, and TP reduced after sheep grazing compared to ungrazed. Water infiltration rate was higher for the G10 management, with greater amount of accumulated infiltrated water. Path analysis showed positive effects of the soil physical attributes under ICLS to the grain yield soybean, allowing the farmers to enhance their profitability.

RESUMO O objetivo deste trabalho foi verificar a contribuição da inoculação de sementes com a bactéria Azospirillum brasilense para a promoção de crescimento sobre os componentes de rendimento na cultura do trigo. Para isso, foram conduzidos experimentos em distintos locais (Santa Maria e Cruz Alta, RS, Brasil), épocas de semeadura (junho e julho) e anos de cultivo (2013 e 2014). Foi utilizado o delineamento de blocos casualisados com três repetições. Os tratamentos foram compostos pela combinação de dez cultivares, três manejos nitrogenados e dois tipos de inoculação (10 x 3 x 2). A inoculação foi realizada com inoculante líquido nas sementes. Foram avaliados os componentes da produtividade de grãos. O número médio de afilhos por planta foi influenciado pela inoculação das sementes (1,63 e 1,72) quando não inoculadas e inoculadas, respectivamente. Já a massa do hectolitro respondeu inversamente reduzindo para 75,7 kg hL-1. A inoculação com A. brasilense aumenta a massa grãos (1%) e não tem influência positiva nas variáveis número de espigas e de espiguetas por espiga, produtividade de grãos e massa hectolítrica.

ABSTRACT The objective of this work was to verify the contribution of seed inoculation with the bacterium Azospirillum brasilense to promote growth on yield components in wheat crop. For this, experiments were carried out in different locations (Santa Maria and Cruz Alta, RS, Brazil), sowing times (June and July) and years of cultivation (2013 and 2014). A randomized block design with three replications was used. The treatments were composed by the combination of ten cultivars, three nitrogen managements and two types of inoculation (10 x 3 x 2). Inoculation was carried out with liquid inoculant in the seeds. The components of grain yield were evaluated. The average number of tillers per plant was influenced by seed inoculation (1.63 and 1.72) when uninoculated and inoculated, respectively. On the other hand, the hectoliter mass responded inversely, reducing to 75.7 kg hL-1. Inoculation with A. brasilense increased the grain mass (1%) and had no positive influence on the variables number of ears and spikelets per ear, grain yield and hectoliter weight.

RESUMO: A massa de hectolitro (MH) é o principal parâmetro quantitativo usado nas unidades de recebimento como indicador de qualidade dos grãos de trigo (Triticum aestivum L.). O teor de umidade e o equipamento utilizado podem ser considerados fontes de variação importantes na classificação de um lote, necessitando correto dimensionamento amostral para mensuração da MH. O objetivo dessa pesquisa foi identificar a variabilidade entre equipamentos para avaliação da MH com correção ou não do teor de umidade da massa de grãos e estimar o número ideal de amostras para classificação comercial de lotes de trigo. O experimento foi realizado em delineamento experimental de blocos ao acaso com quatro repetições. Sete lotes de grãos de trigo, oriundos de diferentes cultivares e/ou locais de produção, foram usados para mensuração da MH em três equipamentos (Equipamento “A”, Equipamento “B” e Equipamento “C”), com e sem correção da umidade dos grãos para 13%. Maiores valores da MH foram determinados no Equipamento “A” (77,15) comparado ao Equipamento “B” (75,08) e Equipamento “C” (74,69), com classificação distinta do trigo quanto ao tipo. O teor de umidade afetou a MH, mas não alterou a classificação final do trigo quanto ao tipo. O número ideal de amostras para MH variou de uma a 18 amostras para o menor nível de precisão (MH = média ± 1 kg hl-1) e, de 67 a 1820 amostras para a maior precisão (MH = média ± 0,1 kg hl-1). O Equipamento “B” requer menor número de amostras (podendo chegar a uma) para um mesmo nível de precisão (MH = média ± 1 kg hl-1), enquanto o Equipamento “A” necessita maior número de amostras para a maioria dos lotes. Assim, a correta classificação do trigo pela MH depende de maior número de amostras.

ABSTRACT: Hectolitre weight (HW) is the principal quantitative parameter used by receiving units as an indicator of the quality of wheat grain (Triticum aestivum L.). The moisture content and the equipment used can be considered important sources of variation to assess a batch, requiring correct sizing of the sample used to measure the HW. This research identified the variability between the equipment used to evaluate HW with or without correcting the grain moisture content, and to estimate the ideal number of samples for the commercial classification of wheat batches. The experiment was carried out in a randomised block design with four replications. Seven batches of wheat grain from different cultivars and/or production sites were used to measure the HW using three types of equipment (Equipment ‘A’, Equipment ‘B’ and Equipment ‘C’), with and without correcting the grain moisture content to 13%. Higher values for HW were determined with Equipment ‘A’ (77.15) compared to Equipment ‘B’ (75.08) and Equipment ‘C’ (74.69), classifying the wheat according to type. The moisture content affected the HW, but did not change the final classification of the wheat in terms of type. The ideal number of samples for HW ranged from 1 to 18 at the lowest level of precision (HW=mean±1 kg hl-1) and from 67 to 1820 samples for the highest precision (HW=mean±0.1 kg hl-1). Equipment ‘B’ requires a smaller number of samples (possibly as few as one) for the same level of precision (HW=mean±1 kg hl-1), whereas Equipment ‘A’ requires a greater number of samples for the majority of batches. Correctly classifying wheat by HW therefore depends on a larger number of samples.

ABSTRACT The interception of photosynthetically active radiation (PAR) is a key factor for biological productivity, and its magnitude depends on the availability of solar radiation, the stage of the plant development cycle, and the arrangement of plant structures. Given the arrangement of the vegetative and reproductive structures in different portions in the canola canopy, the objetive of the study was to morphologically characterize canola cultivars and establish relationships with the stratification of the efficiency of PAR intercep tion. Eight canola cultivars were evaluated in regards to PAR and plant morphological traits. Following the analysis of variance, treatment means were grouped, and the phenotypic correlation matrix between the traits was determined. We observed a strong relationship between the PAR interception efficiency of vegetative and reproductive structures with morphological traits. Plants with a higher number of branches have more siliques and greater efficiency of PAR interception, mainly through the reproductive structures. The characterization of morphological differences between canola cultivars in the PAR interception efficiency should be performed by measures stratified by vegetative and reproductive structures.

RESUMEN La interceptación de radiación fotosintéticamente activa (ARF) es importante para la productividad biológica y su magnitud depende de la disponibilidad de radiación solar, la etapa del ciclo de desarrollo de la planta y la disposición de las estructuras de la planta. Dada la disposición de las estructuras vegetativas y reproductivas de la canola en diferentes porciones del perfil del dosel de las plantas, el objetivo del trabajo fue buscar la caracterización morfológica de cultivares de canola y establecer relaciones con la estratificación de la eficiencia de interceptación de la radiación fotosintéticamente activa. Se evaluaron ocho cultivares de canola, se midió la ARF y se evaluaron los caracteres morfológicos de la planta. Se realizaron análisis de varianza, agrupamiento de medias y se determinó la matriz de correlación fenotípica entre los caracteres. Se observó una alta relación entre la eficiencia de interceptación de la RFA de estructuras vegetativas y reproductivas con caracteres morfológicos. Las plantas con mayor número de ramas tienen más sílice y mayor eficiencia en la interceptación de la radiación fotosintéticamente activa, principalmente debido a las estructuras reproductivas. La caracterización de las diferencias morfológicas entre cultivares de canola en la eficiencia de interceptación de la RFA debe realizarse mediante medidas estratificadas por estructuras vegetativas y reproductivas.

RESUMO O sucesso do sistema de integração lavoura-pecuária depende do correto manejo da pastagem, principalmente quanto às alturas de manejo do pastejo e adubação. Objetivou-se com esta pesquisa avaliar a produção de forragem e a proporção dos componentes botânicos e estruturais de uma pastagem de aveia preta e azevém. Os tratamentos foram organizados em um trifatorial: inoculação de sementes (com e sem inoculação com a bactéria Azospirillum brasilense), manejo de pastejo (pastejo convencional, onde os animais permaneciam na pastagem sem um controle da altura da pastagem, altura da pastagem na saída dos animais de 30, 20 e 10 cm e uma testemunha sem pastejo), e o fator adubação nitrogenada (0, 50 e 100 kg de nitrogênio ha-1). Foi coletada a massa de forragem presente em cada tratamento no momento da entrada e saída dos animais do pastejo e por meio de separação manual dos componentes determinou-se a massa seca de lâminas foliares verdes, massa seca de colmos, massa seca de material senescente, massa seca de inflorescência. A produção total de matéria seca foi obtida pela massa de forragem inicial acrescida das taxas de acúmulo diárias. As proporções dos componentes estruturais variaram em função dos diferentes manejos de pastejo, doses de nitrogênio e inoculação com A. brasilense. A produção de biomassa da pastagem de aveia preta e azevém foi incrementada pela aplicação de nitrogênio e com a inoculação de A. brasilense, sendo possível realizar a substituição do nitrogênio mineral pelo uso de A. brasilense.

ABSTRACT The success of the integrated crop-livestock system depends on the correct pasture management, particularly regarding nitrogen fertilization and grazing intensity. The objective of this study was to evaluate the total production of forage and the proportion of the botanical and structural components of black oat and annual ryegrass mixture. The experimental design was randomized blocks with three replicates and the treatments were arranged in a three-factorial scheme: seed inoculation (with and without Azospirillum brasilense inoculation), grazing management (conventional grazing, where the animals were kept in pasture with no control of pasture height; 30, 20 and 10 cm at the end of grazing, and a control without grazing), and nitrogen fertilization (0, 50 and 100 kg nitrogen ha-1). In treatments with pasture heights where grazing ended at 30, 20 and 10 cm, the height was monitored and biomass was collected when the animals entered and exited the plots. Manual separation of the components was used to determine the dry mass of green leaves, stems, senescent material and inflorescence. Total dry mass production was obtained based on the initial forage mass plus the daily accumulation rates. The proportion of structural components varied according to the different grazing managements, nitrogen doses and inoculation with Azospirillum brasilense. Biomass production of black oat and ryegrass mixture was increased by nitrogen application and Azospirillum brasilense inoculation.

ABSTRACT. Nitrogen is available in insufficient quantities in Brazilian soils, and is the nutrient that raises the most cost of production of maize. Nowadays there is a more interest in the use of alternative nitrogen sources, such as biological nitrogen fixation, to supply plant demand. Among the most used bacteria in association with grasses is Azospirillum brasilense. In this way this study aimed to establish a relationship between the genetic bases of corn and the forms of A. brasilense application and the effects on the plant morphological components, grain yield, and relative nitrogen contribution. Experiments were conducted during the 2013/14 and 2014/15 crop seasons. The experiments included two single hybrids, two double hybrids, and two triple hybrids inoculated with A. brasilense via seed treatment; foliar application during phenological stages V2, V2 + V4, and V4; and a control treatment without bacteria. The response varied with the hybrid and the year. In the 2013/14 crop, a significant difference was observed in the grain yield for the single hybrid AG9045 inoculated with A. brasilense via seed and foliar application in V2. In the 2014/15 crop, inoculation with A. brasilense via seed application resulted in significant increases in the grain yield for the triple hybrid BG7051. Foliar application of A. brasilense is an efficient alternative for the improvement of plant morphological traits, and inoculation via seed and with foliar application in V2 increases the relative contribution of N.

ABSTRACT Desiccation practiced during the preharvest period contributes to mechanized seed harvesting. This work aimed to verify whether wheat preharvest desiccation influences the morphological and physiological characteristics of the seedlings produced from the seeds of desiccated plants. The preharvest treatments included a combination of herbicides (glufosinate-ammonium, glyphosate, and paraquat) and phenological application stages (Zadoks: 83, 85, 87, and 92), as well as a control treatment (without application). Two wheat cultivars were used (BRS Parrudo and TBIO Sinuelo). Herbicide applications were observed to decrease the length and projected area of the shoots by 52 and 46%, respectively, as well as reduce the length, surface area and root volume when compared to the control treatment without application. The hydrogen peroxide concentration, as well as the enzymatic activity of guaiacol peroxidase, was observed to rise only in the treatments where the herbicides were applied. Physiologically, an increased hydrogen peroxide output was revealed, while the guaiacol peroxidase enzymatic activity increased in both cultivars, but with no effect noted in the superoxide dismutase enzymatic activity. The shoot and root morphology were negatively influenced, showing a rise in the enzymatic activity and hydrogen peroxide concentration in the seedlings from the desiccated plants.

Resumen El objetivo del estudio fue comparar dos métodos (Integrador del área foliar LI-COR 3100 y el software ImageJ para estimar el área foliar en el cultivo de avena (Avena sativa L.). Para el efecto se evaluaron dos variedades de avena, una negra (Renascem) y otra blanca (UTF Iguaqu). Se utilizaron seis repeticiones (diseño completamente aleatorio), con la recolección de todas las hojas de una planta seleccionada al azar por parcela cada 7 días y un total de cinco evaluaciones para cada variedad. Las hojas cosechadas fueron identificadas y fijadas sobre una hoja A4 blanca, con una marca de área conocida (45 cm2), fotografiadas y evaluadas utilizando el integrador de área de la hoja (medidor de área LI3100 - LI-COR). Posteriormente en las mismas hojas se midieron las áreas foliares utilizando el software ImageJ. Con los datos obtenidos en cada método se calcularon la desviación estándar, el coeficiente de variación, y la ecuación de regresión lineal simple. Las varianzas de los valores se probaron con la prueba ‘F’ y las medias se compararon con la prueba ‘t’. Al considerar todas las hojas evaluadas por ambos métodos, se encontró que las áreas de las hojas no difieren entre ellas cuando se comparan con los métodos propuestos. Además, tienen altas correlaciones y las variaciones son homogéneas. Como conclusiones, se encontró que el método que usa el software ImageJ puede ser utilizado para reemplazar el integrador del área de la hoja para las variedades de avena evaluados.

Abstract The aim of this study was to compare two methods of estimating leaf area (leaf area meter LI-COR 3100 and ImageJ software) in oats. Renascem black oats and UTF Iguaqu white oats cultivars were evaluated. All the leaves of one plant per plot, with six repetitions, were evaluated every seven days to obtain five assessments for each cultivar. The leaves were identified and fixed on a white A4 sheet of paper with an indication of a known area (45 cm2), photographed and evaluated using a leaf area meter (LI-3100 - LI-COR). Leaf area was then estimated using ImageJ software. Estimates were obtained for standard deviation and coefficient of variation, and a simple linear regression equation was estimated based on the two estimation methods. Mean variances were tested using the ‘F’-test and the means compared by the ‘t’-test. There was no difference between the leaf areas found by both methods. In addition, they were highly correlated, and variances were homogeneous. We concluded that ImageJ software can be used instead of the leaf area meter on the two oat cultivars evaluated.

ABSTRACT. The objectives of this study were to evaluate the effect of the chemical composition of soybean seeds and the efficiency of seed mineral supplementation on physiological quality and field performance. Two seed lots (high and low levels of mineral nutrition), with or without supplemental macro- and micronutrients, of three soybean cultivars (BMX Potência RR, BMX Turbo RR, and BMX Magna RR) were used. For the laboratory experiment, a completely randomized design with four replications was used. To evaluate the physiological quality of the seeds, the water content, first count, germination, 1,000-seed weight, and length and dry weight of the seedling were determined. For the field experiment, a randomized block design with four replications was used, and seedling emergence and grain yield were evaluated. Seeds with higher nutrient content produced seedlings of greater vigor and higher grain yield for all of the cultivars studied. The use of mineral supplementation in seed lots with low nutrient content resulted in greater vigor under laboratory conditions. The increase in grain yield after mineral supplementation depends on the quality of the seed lot.

Resumo: O objetivo deste trabalho foi avaliar alternativas de manejo do nitrogênio em trigo (Triticum aestivum), com uso da inoculação de Azospirillum brasilense nas sementes e nas folhas. Os tratamentos consistiram da inoculação ou não de A. brasiliense, via sementes ou folhas, associada a fertilizações de cobertura com 0, 70 e 140 kg ha-1 de nitrogênio. Três cultivares de trigo foram testadas: BRS Parrudo, TBIO Quartzo e TBIO Sinuelo. O delineamento experimental utilizado foi em blocos ao acaso, com três repetições. Avaliaram-se as seguintes características: número de plantas emergidas, de perfilhos, de espiguetas por espigas, de grãos por espiga e de grãos por espigueta; massa de mil grãos; massa de hectolitro; e produtividade de grãos. O manejo foliar de A. brasilense apresentou melhor associação com a cultivar TBIO Sinuelo. A aplicação de A. brasilense via foliar, realizada individualmente ou associada ao tratamento de sementes, aumenta a produtividade de grãos e os componentes de produtividade das cultivares avaliadas.

Abstract: The objective of this work was to evaluate nitrogen management alternatives using Azospirillum brasilense inoculation in wheat (Triticum aestivum) by seed and foliar applications. Treatments consisted of the inoculation or not of A. brasilense, via seed and leaves, associated with topdressing with 0, 70, and 140 kg ha-1 nitrogen. Three wheat cultivars were tested: BRS Parrudo, TBIO Quartzo, and TBIO Sinuelo. The experimental design was a randomized complete block, with three replicates. The following traits were evaluated: number of emerged plants, tillers, spikelets per ear, grains per ear, and grains per spikelet; 1,000-grain mass; hectoliter mass; and grain yield. The foliar management of A. brasilense showed a better association with the TBIO Sinuelo cultivar. The foliar application of A. brasilense, whether alone or combined with seed treatment, increases the grain yield and yield components of the evaluated cultivars.

ABSTRACT. Inoculation of corn with diazotrophic bacteria reduces the need for nitrogen fertilization and mitigates environmental contamination risks due to the bacteria’s biological nitrogen-fixation capacity. The aim of the present study was to evaluate the effect of corn seed inoculation with Azospirillum brasilense under different nitrogen levels and post-grazing residual heights. The experiment was performed in two growing seasons and conducted in an integrated crop-livestock system for the 2014/15 and 2015/16. A factorial randomized block experimental design with sub-divided plots and three factors. The main plots varied in post-grazing residual height (0.10, 0.20, 0.30 m, continuous grazing, or no grazing), the subplots varied in inoculation (with or without seed inoculation), and the sub-subplots varied in nitrogen level (0, 75, 150, 225, or 300 kg ha-1 of N). The higher post-grazing residual height associated an A. brasilense and nitrogen fertilization resulted in increased corn biomass and production and yield. At the 300 kg dose of N, the highest grain yield was obtained under different post-grazing heights (10.15 Mg ha-1) and in the absence of the bacterium (10.00 Mg ha-1). Azospirillum brasilense helps plant growth and yield but does not replace the effect of N fertilization.

ABSTRACT. Inoculation with nitrogen-fixing bacteria (Bradyrhizobium) is an indispensable technology to increase the productivity of the soybean crop. The objective of this study was to evaluate the viability of the inoculation with Bradyrizobium bacteria associated with the osmoprotector coating on different pre-sowing days and the effect of different soil pH on the components of yield, nodulation and grain yield of soybean. Two soybean cultivars were used, sown in two seasons and submitted to soil pH of 5.3 and 6.5. The seeds were inoculated at different pre-sowin periods with Bradyrizobium bacteria in the presence or absence of osmoprotectants. In the cultivar NA 5909RG (pH 5.3), the seeds inoculated with Bradyrhizobium and osmoprotector, at four and seven days of pre-sowing, presented an increase of 10.8% and 8.3% of productivity, in relation to those without osmoprotector. The osmoprotector and the inoculation of Bradyrhizobium increases the number and dry mass of nodules in soil with more acidic pH. The soil of lower acidity is responsible for higher grain yield, compared to the higher acidity, when both were not inoculated. The variable with the greatest explanatory power and contribution in the variability in the data of the experiment is the grain yield.

RESUMO A eficiência agronômica dos inoculantes fixadores de nitrogênio ou promotores de crescimento é dependente das condições de cultivo das culturas. Um dos fatores que pode influenciar essa resposta é a interação da bactéria presente no inoculante com o tratamento químico das sementes. Dessa forma, o estudo teve por objetivo avaliar a influência da inoculação de sementes de trigo com Azospirillum brasilense e sua interação com o tratamento de sementes na germinação, vigor e crescimento inicial de plantas de trigo de quatro cultivares. Para tal conduziu-se um experimento no Laboratório Didático e de Pesquisa em Sementes do Departamento de Fitotecnia da Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul. O delineamento experimental utilizado foi o inteiramente casualizado, em um trifatorial (4x4x2), sendo representado pelas combinações dos fatores cultivar (FUNDACEP Bravo, OR/TBIO Quartzo, TBIO Itaipu e BRS 331), tratamento químico de sementes (1- Inseticida + Fungicida; 2- Inseticida; 3- Fungicida; 4- Testemunha sem tratamento) e inoculação de Azospirillum brasilense (com e sem inoculante). As determinações realizadas foram: emergência em canteiros, primeira contagem do teste de germinação (vigor), germinação, comprimento de plântulas (raiz, parte aérea e total), massa seca (raiz e parte aérea). As respostas aos inoculantes com Azospirillum brasilense estão intimamente relacionadas às cultivares utilizadas no estudo. O tratamento de sementes com fungicida e inseticida apresentou efeito fitotóxico prejudicando o crescimento inicial das plântulas.

ABSTRACT The agronomic efficiency of the nitrogen-fixing inoculants or growth promoters depends on the growing conditions of the crops. One of the factors that may influence this response is the interaction between the bacteria present in the inoculant with the chemical treatment applied to the seeds. The objective of this study was to evaluate the influence of inoculation of wheat seeds with Azospirillum brasilense and its interaction with seed treatment on germination, vigor and initial growth of wheat plants of four cultivars. So, an experiment was carried out at the Federal University of Santa Maria, Santa Maria-RS. The experimental design was a completely randomized in a three-factorial (4x4x2), represented by the combinations between cultivar (FUNDACEP Bravo, OR/TBIO Quartzo, TBIO Itaipu e BRS 331), chemical treatment (1: Insecticide + Fungicide; 2: Insecticide; 3:Fungicide; 4: Witness without treatment) and Azospirillum brasilense inoculation (with and without inoculant). The determinations which were carried out were the following: emergence in beds, first germination test counting (vigor), germination, seedling length (root, aerial part and total), dry mass (root and aerial part). The responses to inoculants with Azospirillum brasilense are closely related to the cultivars used in the study. The treatment of seeds with fungicide and insecticide presented a phytotoxic effect, damaging the initial growth of the seedlings.

RESUMO Objetivou-se com este trabalho avaliar os parâmetros fitomorfológicos da cultura da soja em um sistema de integração lavoura-pecuária e inoculados com Azospirillum brasilense. O experimento foi conduzido em Santa Maria, em dois agrícolas (2012/2013 e 2013/2014), num delineamento experimental de blocos casualizados, com três repetições. No período de inverno a pastagem de aveia preta e azevém foi manejada com ovinos em diferentes sistemas de pastejo: (I) - pastejo convencional (PC), onde os animais permaneciam na pastagem por todo o período experimental sem um controle da altura da pastagem, (II,III e IV) - altura da pastagem na saída dos animais de 10, 20 e 30 cm e uma testemunha sem pastejo (SP), três doses de nitrogênio (0, 50 e 100 kg ha-1) e com ou sem inoculação (Azospirillum brasilense). A semeadura da soja foi realizada em semeadura direta em 16 de novembro de 2012 e 01 de dezembro de 2013, utilizando-se a cultivar BMX Potência RR. Em cada parcela, se utilizou sete fileiras de plantas com espaçamento de 0,45 m, sendo que em quatro fileiras as sementes foram inoculadas com a bactéria Azospirillum brasilense. Foram avaliadas variáveis fitomorfológicas e a produtividade de grãos. Em sistema de integração lavoura-pecuária a cultura da soja possui melhores produtividades quando estabelecida sobre pastagem de aveia preta e azevém manejadas com alturas de pastejo entre 20 e 30 cm. As áreas sob pastejo convencional no inverno proporcionam plantas de soja menores, com menores inserções de primeira e última vagem. A inoculação com Azospirillum brasilense não deve ser usada isoladamente na cultura da soja.

ABSTRACT The objective of this study was to evaluate the phytomorphological parameters of soybean in a crop-livestock system inoculated with Azospirillum brasilense. The experiment was conducted in Santa Maria, Brazil, for two agricultural years (2 Paper extracted from the doctoral thesis of the first author. 012/2013 and 2013/2014) in a randomized complete block design with three replications. In the winter, the black oat and ryegrass pasture was managed with sheep under different grazing systems: (I) - a conventional grazing (CG) system, where the animals remained in the pasture throughout the experimental period without any pasture height control; (II, III, and IV) - systems with post-grazing pasture heights of 10, 20, and 30 cm, respectively; and (NG) - one control without grazing. All treatments received two nitrogen doses (50 and 100 kg ha-1) and inoculation or no inoculation (A. brasilense). The soybean cultivar BMX Potência RR was sown using no-tillage on 16 November 2012 and 1 December 2013. In each plot, seven rows of plants with spacing of 0.45 m were used, and in four rows, the seeds were inoculated with the bacterium A. brasilense. The phytomorphological variables and grain productivity were evaluated. In a croplivestock system, soybean has better productivity when established on black oat and ryegrass pasture managed with post-grazing pasture heights of between 20 and 30 cm. Areas under conventional grazing in the winter led to smaller soybean plants with lower first and last pod heights. Inoculation with A. brasilense should not be used alone in soybean cultivation.

RESUMO Sementes podem absorver N de suplementos minerais, estimulando o desenvolvimento de plântulas. O estudo objetivou avaliar a contribuição de N derivado da suplementação mineral em sementes com diferentes teores nutricionais, para plântulas de soja. Sementes de dois lotes da cultivar BMX Potência RR, contrastantes quanto ao teor nutricional, foram submetidas a aplicação de suplemento mineral enriquecido com 2,5% átomos de 15N em excesso. Aos 2, 6 e 10 dias após a semeadura em papel toalha, plântulas foram coletadas, separadas em cotilédones, sistema radicular e parte aérea. A produção de matéria seca, o comprimento e volume do sistema radicular foram avaliados. No tecido dos órgãos das plântulas foram analisados os totais de N e 15N. As sementes derivadas do lote com menor teor nutricional absorveram mais N do suplemento mineral, que foi acumulado nos cotilédones e redistribuído para o sistema radicular e parte aérea. A maior parte do N na soja ao longo de 10 dias após a semeadura é derivada das reservas da semente independentemente do teor nutricional inicial. A aplicação de N via suplementação mineral é de pouca importância para o crescimento e desenvolvimento de plântulas.

ABSTRACT Seeds can absorb N from mineral supplementation, thus stimulating seedling development in soybeans (Glycine max (L.) Merrill). This study aimed to evaluate the contribution to soybean seedlings of N derived from mineral supplementation in seeds with different nutritional contents. Seeds of the cultivar BMX Potência RR received mineral supplementation enriched with 2.5% excess 15N. The treatments were performed in seeds in two lots, one with high and one with low nutritional content. At 2, 6 and 10 days after sowing on paper towels, the seedlings were collected and separated into cotyledons, roots and shoots. Dry matter production, root length and root volume were assessed. Total N and 15N values were analyzed in the seedling organ tissues. The seeds from the lot with lower nutritional content absorbed more N from the mineral supplement, which was accumulated in the cotyledons and redistributed to the root systems and cotyledons. At 10 days after sowing, most of the N in the organs of soybean seedlings was derived from the seed reserves, regardless of nutritional content. Thus, application of N through mineral supplementation is of low importance for the development and nutrition of seedlings.