Docência Universitária: o professor agrônomo na construção de sua professoralidade

The aim of this study was to understand how does the teaching learning process of the agronomy professor from Universidade Federal de Uberlândia occurs, analyzing the relationship among training, knowledge and these professors professional identity. The questions which guided the research were: How does the professional identity of these professors are developed in the teaching learning process? Which are the main formation factors that influences this process? Which are the agronomy professors knowledge and how were them built and learned by these professionals in college? This is a research with a qualitative approach, in which most of the data was collected with the professors, through two questionnaires, a simplified and an in-depth one, as well as documents that depict the history of the institute and of the Agronomy department. To guide analysis, we have used, more than the scientific production in the area, the authors Cunha (2008), Tardif (2002), Pimenta (2005), Melo (2009, 2012), Malusá (2005), Pachane (2009), Magalhães (2012), Dubar (2005), Imbernón (2002),Nunez andRamalho (2008), Almeida andPimenta (2012) PimentaandAnastasiou (2002), Cavallet (1999) Pachane (2006), Behrens (2007) Isaia (2008), Malusá (2012) and Nóvoa (1999). The analysis indicated that the teaching learning process of the agronomy professor occurs since college, with the option of been a professor, and throughout their teaching career. Their challenges are related to work conditions, although, the dilemmas between the practices related to the conceptions of traditional and progressive pedagogy can be seen in their class, teaching and teaching learning process conception. Classes are considered by professors as an interaction place but also as a knowledge transference place. This research identifies the necessity of promote cooperation between teachers, so that, the collective and integrated work in formative spaces teachers will have the opportunity to develop the knowledge necessary for teaching. The implementation of institutional initial and continuous formation, through direct dialogue between undergraduate, graduate and training and professional development programs for teachers, with better work conditions will reflect in the constant improvement of training development within universities.

Habilidade competitiva do feijoeiro e sua tolerância ao herbicida Ethoxysulfuron

The presence of weeds decreases the crop yield. Among the alternatives to reduce the crop yield loss, it can be included to increase the competitive ability of the crop and the chemical control of the weeds. A research program was developed in the course of Agronomy at Federal Technological University at Paraná, Campus Pato Branco - PR, during the years 2015/16, with the objectives evaluating if gibberellin inhibitors increase the competitive ability of bean plants, making them insensitive to the initialism, extending the period prior to weed-crop interference. Evaluate the tolerance of common bean plants to the herbicide ethoxysulfuron and investigate the existence of relationship between the plant mass and the level of tolerance of the plants to the herbicide. Evaluate the effect of increasing doses of ethoxysulfuron on morphological characteristics, yield components and grain yield of the bean cultivars IPR Tangará and IPR Andorinha. Evaluate the effect of increasing doses of ethoxysulfuron on the development of IAC Imperador and the community of weeds present in the area. Elucidate the mechanism that confers tolerance to bean plants to the herbicide ethoxysulfuron. The results indicate that gibberellin inhibitors were not effective in increasing periods of weed-crop coexistence. Trinexapac-ethyl increased 20% the grain yield of bean plants. It was observed high variability as the response of bean cultivars to the herbicide ethoxysulfuron, however, despite high doses (200 g ha-1), it was not observed death of the plants. The field results indicate that when the ethoxysulfuron dose is 83.2 g ha-1, the reduction in grain yield can reach 40% with the cultivar IPR Tangará and 30% in the cultivar IPR Andorinha. However, respectively for each cultivar cited, ethoxysulfuron at 17 and 12 g ha-1 are enough to reduce 10% of grain yield. Evaluating the control of weeds within the bean crop cultivar IAC Imperador with the herbicide ethoxysulfuron, it was observed that doses at 20 g ha-1 are enough to control soybean and Ipomoea spp. plants. But, due to the level of plant injury, the crop grain yield increase was not sufficient to match the one observed on the weed-free untreated control. The mechanism of tolerance of bean plants to ethoxysulfuron appears to be the herbicide degradation.

New sweetpotato cultivars to meet market needs

The Australian Sweetpotato Growers Association partnered researchers from Agri-Science Queensland (with co-funding from Horticulture Australia Limited) to identify new, high performing sweetpotato cultivars with diverse colours and tastes. The project evaluated a mix of purple, red, orange and white skin and flesh, tailored for Australian growers and consumers. Australia's sweetpotato market currently relies on one gold cultivar for 90% of national production. Major retailers were requesting a reliable supply of quality sweetpotatoes in emerging categories such as red or white skin or purple flesh. To identify suitable cultivars, over 40 new sweetpotato cultivars were virus tested, and extensively evaluated in multiple experiments in Queensland and northern New South Wales. Larger-scale plantings by growers, using standard agronomy, provided additional performance feedback under commercial conditions. In partnership with growers and wholesalers, cultivars were evaluated in field and laboratory for desired characteristics such as shape, size range, skin and flesh colour, estimates of productivity and suitability for commercial production, cooking characteristics and taste. New high performing gold cultivars had better soil insect and nematode tolerance than the current cultivars. The new colours offered diverse health-related opportunities for consumers, more anthocyanins in purple-fleshed cultivars; higher beta carotene content in new gold fleshed cultivars; and potentially lower GI in white-fleshed cultivars. To enhance adoption, the industry/research partnership will tailor agronomic guidelines to maximise on-farm performance and identify niche marketing pathways for each of the cultivars. Increased consumption of this versatile vegetable will drive sweetpotato industry development and expansion into the future.

Nitrogen use efficiency in summer sorghum grown on clay soils

Nitrogen fertilizer inputs dominate the fertilizer budget of grain sorghum growers in northern Australia, so optimizing use efficiency and minimizing losses are a primary agronomic objective. We report results from three experiments in southern Queensland sown on contrasting soil types and with contrasting rotation histories in the 2012-2013 summer season. Experiments were designed to quantify the response of grain sorghum to rates of N fertilizer applied as urea. Labelled 15N fertilizer was applied in microplots to determine the fate of applied N, while nitrous oxide (N2O) emissions were continuously monitored at Kingaroy (grass or legume ley histories) and Kingsthorpe (continuous grain cropping). Nitrous oxide is a useful indicator of gaseous N losses. Crops at all sites responded strongly to fertilizer N applications, with yields of unfertilized treatments ranging from 17% to 52% of N-unlimited potential. Maximum yields ranged from 4500 (Kupunn) to 5450 (Kingaroy) and 8010 (Kingsthorpe) kg/ha. Agronomic efficiency (kg additional grain produced/kg fertilizer N applied) at the optimum N rate on the Vertosol sites was 23 (80 N, Kupunn) to 25 (160N, Kingsthorpe), but 40-42 on the Ferrosols at Kingaroy (70-100N). Cumulative N2O emissions ranged from 0.44% (Kingaroy legume) to 0.93% (Kingsthorpe) and 1.15% (Kingaroy grass) of the optimum fertilizer N rate at each site, with greatest emissions from the Vertosol at Kingsthorpe. The similarity in N2O emissions factors between Kingaroy and Kingsthorpe contrasted markedly with the recovery of applied fertilizer N in plant and soil. Apparent losses of fertilizer N ranged from 0-5% (Ferrosols at Kingaroy) to 40-48% (Vertosols at Kupunn and Kingsthorpe). The greater losses on the Vertosols were attributed to denitrification losses and illustrate the greater risks of N losses in these soils in wet seasonal conditions.

NITROUS OXIDE EMISSIONS IN COVER CROP-BASED CORN PRODUCTION SYSTEMS

Nitrous oxide (N2O) is a potent greenhouse gas; the majority of N2O emissions are the result of agricultural management, particularly the application of N fertilizers to soils. The relationship of N2O emissions to varying sources of N (manures, mineral fertilizers, and cover crops) has not been well-evaluated. Here we discussed a novel methodology for estimating precipitation-induced pulses of N2O using flux measurements; results indicated that short-term intensive time-series sampling methods can adequately describe the magnitude of these pulses. We also evaluated the annual N2O emissions from corn-cover crop (Zea mays; cereal rye [Secale cereale], hairy vetch [Vicia villosa], or biculture) production systems when fertilized with multiple rates of subsurface banded poultry litter, as compared with tillage incorporation or mineral fertilizer. N2O emissions increased exponentially with total N rate; tillage decreased emissions following cover crops with legume components, while the effect of mineral fertilizer was mixed across cover crops.

Polinização por Apis mellifera em soja em soja transgênica [Glycine max (L.) Merrill] Merrill] Roundup ReadyTM cv. BRS 245 RR e convencional cv. BRS 133.

RESUMO: O objetivo deste estudo foi verificar a influência de Apis mellifera na produção de grãos e qualidade de sementes da soja transgênica Glycine max (L.) Merrill Roundup ReadyTM e convencional. A soja transgênica foi plantada intercalada com a convencional, em 18 parcelas, em três tratamentos: gaiolas com abelhas A. mellifera, gaiolas sem abelhas e áreas descobertas, com livre visitação de insetos. Na soja transgênica, em três parcelas de cada tratamento, foi aplicado glifosato, 30 dias após a emergência. Os parâmetros analisados foram: produção de grãos; número de vagens por planta; peso de 100 sementes e porcentagem de germinação das sementes. Não houve diferença entre as cultivares, entretanto a produção de 2.757,40 kg ha-1 obtida na área coberta por gaiola com abelhas, e 2.828,47 kg ha-1 na área livre para visitação de insetos foram superiores a 2.000,53 kg ha-1 da área coberta por gaiola sem abelhas. O número de vagens por planta foi maior na área coberta por gaiola com abelhas (38,28) e área livre (32,65), quando comparado com o da área coberta por gaiola sem abelhas (21,19). O peso médio de 100 sementes e a germinação das sementes não foram diferentes entre as cultivares e nem entre os tratamentos. Conclui-se que, para as cultivares estudadas, houve benefício na produção de grãos de 37,84%, quando foi permitida a visita de abelhas. ABSTRACT. Pollination by Apis mellifera in transgenic soy (Glycine max (L.) Merrill) Roundup Ready? cv. BRS 245 RR and conventional cv. BRS 133. This research was carried out to evaluate the influence of Africanized honeybees in grain production and seed quality of Glycine max (L.) Merrill Roundup Ready? transgenic soy, as well as of conventional soy. Transgenic soy was interposed with conventional soybean, in 18 plots and three treatments: covered area with Africanized honeybees, covered area without honeybees, and uncovered area with free insect visitation. The herbicide Glyphosate was applied on three plots of each treatment of transgenic soy, 30 days after emergence. Grain production, number of pods/plant, weight per 100 seeds, and seed germination percentage were evaluated. There was no difference among cultivars; however, the production in the covered area with honeybees (2757.4 kg ha-1) and in the uncovered area (2828.47 kg ha-1) were higher than in the covered area without honeybees (2000.53 kg ha-1). The number of pods/plant was greater than in the covered area with honeybees (38.28) and in the uncovered area (32.65) as compared to the covered area without honeybees (21.19). The weight per 100 seeds seed germination did not differ among cultivars or treatments. It can be concluded that, for these cultivars, there was a rise in grain production of 37.84% when honeybee visits were allowed.

Buckwheat as a Cover Crop in Florida: Mycorrhizal Status, Soil Analysis, and Economic Assessment

This thesis analyses buckwheat as a cover crop in Florida. The study was designed to demonstrate: soil enrichment with nutrients, mycorrhizal arbuscular fungi interactions, growth in different soil types, temperature limitations in Florida, and economic benefits for farmers. Buckwheat was planted at the FIU organic garden (Miami, FL) in early November and harvested in middle December. After incorporation of buckwheat residues, soil analyses indicated the ability of buckwheat to enrich soil with major nutrients, in particular, phosphorus. Symbiosis with arbuscular mycorrhizal fungi increased inorganic phosphorus uptake and plant growth. Regression analysis on aboveground buckwheat biomass weight and soil characteristics showed that high soil pH was the major limiting factor that affected buckwheat growth. Spatial analysis illustrated that buckwheat could be planted in South Florida throughout the year but might not be planted in North and Central Florida in winter. An economic assessment proved buckwheat to be a profitable cover crop.

Spondias tuberosa trees grown in tropical, wet environments are more susceptible to drought than those grown in arid environments.

In this study, we investigated the different responses of Spondias tuberosa (umbu) trees, which grow in two different ecological life zones in northeast Brazil: tropical wet and tropical arid ecosystems. We evaluated the responses of plants grown under humid and dry conditions by measuring the photosynthesis, water status, fluorescence parameters, carbon isotopes and antioxidant system activity. The higher net photosynthesis values were recorded contemporaneously with the lower VPD values. The highest internal-to-ambient CO2 concentration and the absence of typical changes in the fluorescence parameters suggested an onset of a nonstomatal limitation in the photosynthesis. Our results showed that umbu plants can adjust their antioxidant activity during the dry season as a defensive strategy against the deleterious effects of water stress. This evidence is supported by the observed modifications in the pigment concentrations, increased accumulation of hydrogen peroxide and malondialdehyde, high levels of electrolyte leakage, increased antioxidant activity, and decreased carbon isotope discrimination in the umbu trees during the dry season. Supported by multivariate analysis of variance, significantly effect of interaction between categorical months of collect and location predicts a strong ?dry season effect? on our dataset. Taken together, our data show that umbu trees grown in a wet tropical environment are more susceptible to drought, as compared with their tropical arid counterparts.

Annual crop rotation of tropical pastures with no-till soil as affectedby lime surface application.

Soil acidity and low natural fertility are the main limiting factors for grain production in tropical regionssuch as the Brazilian Cerrado. The application of lime to the surface of no-till soil can improve plant nutrition, dry matter production, crop yields and revenue. The present study, conducted at the Lageado Experimental Farm in Botucatu, State of São Paulo, Brazil, is part of an ongoing research project initi-ated in 2002 to evaluate the long-term effects of the surface application of lime on the soil?s chemical attributes, nutrition and kernel/grain yield of peanut (Arachis hypogaea), white oat (Avena sativa L.) and maize (Zea mays L.) inter cropped with palisade grass (Urochloa brizantha cv. Marandu), as well as the forage dry matter yield of palisade grass in winter/spring, its crude protein concentration, estimated meat production, and revenue in a tropical region with a dry winter during four growing seasons. The experiment was designed in randomized blocks with four replications. The treatments consisted of four rates of lime application (0, 1000, 2000 and 4000 kg ha−1), performed in November 2004. The surface application of limestone to the studied tropical no-till soil was efficient in reducing soil acidity from the surface down to a depth of 0.60 m and resulted in greater availability of P and K at the soil surface. Ca and Mg availability in the soil also increased with the lime application rate, up to a depth of 0.60 m. Nutrient absorption was enhanced with liming, especially regarding the nutrient uptake of K, Ca and Mg by plants.Significant increases in the yield components and kernel/grain yields of peanut, white oat and maize were obtained through the surface application of limestone. The lime rates estimated to achieve the maximum grain yield, especially in white oat and maize, were very close to the rates necessary to increase the base saturation of a soil sample collected at a depth of 0?0.20 m to 70%, indicating that the surface liming of 2000 kg ha−1is effective for the studied tropical no-till soil. This lime rate also increases the forage dry matter yield, crude protein concentration and estimated meat production during winter/spring in the maize-palisade grass inter cropping, provides the highest total and mean net profit during the four growing seasons, and can improve the long-term sustainability of tropical agriculture in the Brazilian Cerrado.

Beyond conservation agriculture.

ABSTRACT: Global support for Conservation Agriculture (CA) as a pathway to Sustainable Intensification is strong. CA revolves around three principles: no-till (or minimal soil disturbance), soil cover, and crop rotation. The benefits arising from the ease of crop management, energy/cost/time savings, and soil and water conservation led to widespread adoption of CA, particularly on large farms in the Americas and Australia, where farmers harness the tools of modern science: highly-sophisticated machines, potent agrochemicals, and biotechnology. Over the past 10 years CA has been promoted among smallholder farmers in the (sub-) tropics, often with disappointing results. Growing evidence challenges the claims that CA increases crop yields and builds-up soil carbon although increased stability of crop yields in dry climates is evident. Our analyses suggest pragmatic adoption on larger mechanized farms, and limited uptake of CA by smallholder farmers in developing countries. We propose a rigorous, context-sensitive approach based on Systems Agronomy to analyze and explore sustainable intensification options, including the potential of CA. There is an urgent need to move beyond dogma and prescriptive approaches to provide soil and crop management options for farmers to enable the Sustainable Intensification of agriculture.

Productivity and chemical composition of food-type soybeans sown on different dates.

ABSTRACT. The objective of this study was to investigate the effect of different sowing dates on the yield, 100-grain weight, oil, protein and isoflavone contents of food-type soybean breeding lines UEL 110, UEL 115 and UEL 123 and a cultivar BRS 257. The materials were seeded on four sowing dates, and the experiment was conducted in a randomized block design with four replications. The productivity and 100- grain weight varied with the sowing dates and soybean genotypes. The protein content ranged from 36.40 to 42.44%, and the oil content ranged from 18.29 to 22.71%. No significant interaction was found between the genotype and sowing dates for the protein content. The isoflavone content also varied with the sowing dates and soybean genotypes. The cultivar BRS 257 had the highest isoflavone content, including the β- glucoside, malonyl glucoside and aglycones forms. The different sowing dates influenced the productivity, 100-grain weight, oil and protein content and isoflavone levels. Higher temperatures and lower rainfall during the grain filling decreased the productivity and isoflavone content and increased the protein content. For all sowing dates, the BRS 257 soybean food-type cultivar showed the highest isoflavone content, indicating that the effect of genotype is more important. Keywords: soybean, oil, protein, isoflavones. RESUMO. O objetivo deste trabalho foi investigar o efeito das diferentes épocas de semeadura na produtividade, massa de 100 grãos, teor de proteínas, óleo e isoflavonas de linhagens de soja tipo alimento UEL 110, UEL 115 e UEL 123 e cultivar BRS 257. O material foi semeado em quatro épocas de semeadura e o experimento foi conduzido em blocos casualizados com quatro repetições. A produtividade e a massa de 100 grãos variaram com a época de semeadura e com os diferentes genótipos. O teor de proteínas variou de 36,40 a 42,44% e o de óleo de 18,29 a 22,71%. Não foi encontrada interação entre genótipo e épocas de semeadura para o teor de proteínas. O teor de isoflavonas variou com as épocas de semeadura e com os genótipos. A cultivar BRS 257 apresentou maior teor de β-glicosídeos, malonil-glicosídeos e agliconas. As diferentes épocas de semeadura influenciam a produtividade, massa de 100 grãos, conteúdo de óleo, proteínas e isoflavonas. Altas temperaturas e baixas precipitações durante o enchimento dos grãos reduzem a produtividade e teor de isoflavonas e aumentam o teor de proteínas. A cultivar BRS 257 apresenta o maior teor de isoflavonas indicando que o efeito genético é mais importante.

Effects of row spacing and nitrogen topdressing fertilization on the yield of upland rice in a no-tillage system.

This study aimed to evaluate the effect of row spacing and nitrogen topdressing fertilization of two materials (genotype 07SEQCL441 CL and cultivar BRS Esmeralda) on the plant height, yield components, grain yield, and quality of an upland rice crop grown in a no-tillage system. Trials were conducted for two growing seasons under field conditions in a 3 x 4 factorial, randomized, complete block design, with four replications. For each material, treatments consisted of the combination of row spacing (0.225, 0.35, and 0.45 m) with nitrogen (N) applied as topdressing (0, 50, 100, and 150 kg ha-1). The lowest row spacing (0.225 m) for genotypes 07SEQCL441 CL and BRS Esmeralda provided a higher number of tillers, number of panicles m-2, and grain yield of rice. Increasing rates of N in the topdressing improved the rice grain yield for both cultivars, but for 07SEQCL441 CL, the grain yield was positively affected only to applications up to 50 kg N ha-1. Row spacing and N rates did not affect the rice grain quality. Therefore, these results indicate that the narrowest row spacing used (0.225 m) with N fertilization as topdressing increased the rice grain yield most in the no-tillage system.