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.

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 O trigo é uma das principais culturas de inverno na região Sul do Brasil e para que a sua produtividade seja maximizada necessita que não haja restrições bióticas ou abióticas que possam afetar seus componentes de rendimento. Dessa forma, objetivou-se com esse trabalho avaliar as alterações provocadas nos componentes do rendimento da cultura de trigo pela aplicação de silício via foliar. O experimento foi conduzido em dois anos agrícolas. No primeiro ano foram avaliadas cinco cultivares de trigo (Quartzo, Campo Real, Horizonte, Ônix e Linhagem Fundacep), e quatro cultivares no segundo ano (Mirante, Campo Real, Horizonte e Quartzo), em ambos os anos foram submetidas a três doses de silício (0, 3 e 6 L de silício ha-1). As aplicações de silício foram realizadas nas fases do afilhamento, alongamento e antese. Os componentes de rendimento avaliados foram o número de plantas, o número de espigas e o número afilhos férteis, matéria seca por planta, massa de hectolítro, número de espiguetas, número de grãos por espiga, massa de cem grãos, produção de grãos e índice de colheita. A maioria dos componentes de rendimento não respondeu a aplicação foliar de silício. Contudo, o índice de colheita (primeiro ano) e o número de afilhos (segundo ano) apresentaram incrementos de suas características com a adição da adubação com silício via foliar. As demais diferenças observadas são atribuídas às variações entre as cultivares de trigo.

ABSTRACT Wheat is a major winter crop in southern Brazil. To maximize its productivity, there should be no biotic or abiotic restrictions that can affect the yield components. Thus, the objective was to evaluate the changes caused in the wheat crop yield components by silicon foliar application. The experiment was conducted in two growing seasons. In the first year, five wheat cultivars (Quartzo, Campo Real, Onix and Fundacep Lineage) were assessed and in the second year four were assessed (Mirante, Campo Real, Horizonte and Quartzo). In both years the crops were subjected to three doses of silicon (0, 3 and 6 L of silicon ha -1). The silicon was applied during the tillering, booting and anthesis stages. The yield components assessed were the number of plants, number of ears, number of fertile tillers, dry matter per plant, hectoliter weight, number of spikelets, number of grains per spike, weight of hundred grains, grain yield and harvest index. Most yield components did not respond to the silicon foliar application. The harvest index (first year) and the number of tillers (second year) however presented a quadratic relationship with the supply of silicon. The remaining differences were attributed to variations among the wheat cultivars.

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.

O estande de plantas é um dos principais componentes do rendimento que altera a produtividade das culturas, maximizando o ambiente produtivo para a cultura. Nesse sentido, objetivou-se com este trabalho avaliar a produção de forragem e a composição química de duas espécies de ervilhaca em diferentes densidades de semeadura. O experimento foi conduzido no ano de 2011, em área experimental do Departamento de Fitotecnia da Universidade Federal de Santa Maria, Rio Grande do Sul. Os tratamentos constaram de duas espécies de ervilhaca (ervilhaca peluda e ervilhaca comum) em quatro densidades de semeadura (50, 100, 150 e 200 sementes m-2). O delineamento experimental utilizado foi o de blocos ao caso, disposto em fatorial (2x4), em quatro repetições. Os valores de FDA aumentaram conforme o aumento da densidade de semeadura, o que não ocorreu para as demais características bromatológicas avaliadas. A densidade ótima de semeadura deve ser ajustada conforme a espécie e o corte, variando de 66 a 200 sementes viáveis por metro quadrado. A produção de massa seca total é maximizada quando a densidade de semeadura for de 136 sementes viáveis m-2

The plant stand is one of the main yield components amending crop productivity, maximizing productive environment for culture. In this sense the objective with this study was to evaluate forage production and chemical composition of two cultivars of common vetch at different densities. The experiment was conducted in 2011, in an area of the Crop Science of the Department of the Federal University of Santa Maria, Rio Grande do Sul. Treatments consisted of two genotypes of vetch (hairy vetch and common vetch) at four seeding rates (50, 100, 150 and 200 seeds m-2). The experimental design was a randomized blocks design, arranged in (2x4) factorial design with four replications. The ADF values increased with increasing seeding rate, which did not occur for the other qualitative characteristics evaluated. The optimum seeding rate should be adjusted according to the cultivar and cutting, ranging 66-200 viable seeds per square meter. The total dry matter production is maximized when the seeding rate is 136 seeds m-2

A bovinocultura de leite apresenta grande importância económica para várias regiões do Brasil e nos últimos anos houve mudanças significativas no setor. O presente trabalho teve por objetivo realizar uma revisão da utilização da modelação para a determinação de genótipos de milho mais indicados para a produção de silagem e, por conseguinte, produção de leite. Com a utilização de técnicas como o uso de modelos matemáticos e softwares, é possível planear as atividades da propriedade rural de forma rápida, minimizando esforços e possibilitando a redução de tempo para a tomada de decisão. Uma dessas formas é a utilização de folhas de cálculo que permitem a estimativa de produção de leite a partir de parâmetros bromatológicos e da produção de milho para silagem. Essa ferramenta é importante, pois no Brasil a dinâmica de produção de milho faz com que exista uma grande quantidade de genótipos disponíveis no mercado.

The dairy cattle present great economic importance for many regions in Brazil and in recent years there have been significant changes in the industry. This paper aims to review the use of modelling for the determination of maize genotypes more suitable for silage production and hence milk production. With the use of techniques, such as mathematical models and software, is possible to plan the activities of the rural property quickly, minimizing effort and time for decision making. One of these ways is to use spreadsheets which allow estimates of milk production based on parameters of production and nutritional qualities of maize for silage. This tool is important because in Brazil the production dynamics of maize genotypes means that there is a large amount of genotypes available in the market.