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. 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. A redução da população de plantas de trigo ocorre por diversos fatores, os quais podem comprometer o estabelecimento inicial da cultura e consequentemente afetar os componentes de rendimento e a produtividade de grãos. O objetivo do presente trabalho foi de realizar uma análise econômica com ênfase na indicação de ressemeadura de trigo em função da redução aleatória do estande de plantas, do custo de produção e da expectativa de retorno financeiro. Foram conduzidos experimentos em dois anos agrícolas (2011 e 2012), na área Experimental da Coxilha, pertencente ao Departamento de Fitotecnia da Universidade Federal de Santa Maria, RS (Brasil). Efetuaram-se retiradas aleatórias de plantas de trigo, correspondendo a 0, 20, 40 e 60% da população inicial das cultivares Horizonte, Marfim, Campo Real, Mirante e Quartzo. As características avaliadas foram o número de plantas, espigas e produtividade de grãos. Verificou-se que as cultivares Horizonte, Marfim e Campo Real demonstraram ser estáveis e capazes de compensar perdas causadas pela redução do estande de plantas. A produção de grãos das cultivares Mirante e Quartzo são dependentes do número de plantas estabelecidas, devendo-se assim garantir um bom estabelecimento da lavoura para que não hajam prejuízos. Portanto, as cultivares Mirante e Quartzo não compensam a redução na população de plantas, necessitando ser ressemeadas caso o número de plantas não seja adequado. Nesses casos, a viabilidade econômica pode ser verificada. Enquanto que as cultivares Horizonte, Marfim e Campo Real são mais estáveis não sendo recomendado a ressemeadura devido a inviabilidade econômica.

ABSTRACT. There are several factors that may compromise the initial establishment of wheat crops, reduce the plant populations, and consequently affect yield components and grain yield. The objective of this study was to produce reseeding recommendations for wheat crops affected by reduced plant stands based on an economic analysis of the yield cost and the expectation of financial return. Experiments were conducted during two agricultural years (2011 and 2012) in the Experimental da Coxilha area, which belongs to the Department of Plant Science of Universidade Federal de Santa Maria, in the state of Rio Grande do Sul (Brazil). Random removals of wheat plants were undertaken, corresponding to 0, 20, 40, and 60% of the initial population of plants for the following cultivars: Fundacep Horizonte, Marfim, Fundacep Campo Real, Mirante and Quartzo. The characteristics that were evaluated included the number of plants and ears, as well as the grain yield. The Fundacep Horizonte, Marfim and Fundacep Campo Real cultivars were stable and able to compensate for losses caused by reductions in the plant stands. The yield production of Mirante and Quartz cultivars was dependent on the number of established plants and therefore relied on good establishment of the initial crop and no subsequent losses. Thus, the findings of this study indicate that the Mirante and Quartz cultivars do not compensate for reductions in plant populations and need to be reseeded if the number of plants is not appropriate. In such cases, the economic viability of reseeding can be quantified. In contrast, the Fundacep Horizonte, Marfim, and Fundacep Campo Real cultivars are more stable, and reseeding is not economically justified at these locations.