Juaci Vitória Malaquias

Desenvolvimento de modelos preditores de acúmulo de forragem em pastagens tropicais

The objective of this work was to identify, quantify and model conditioning attributes of forage accumulation in Central Brazil, and to develop estimating models of the forage accumulation potential, based on climatic parameters. A database structure was modeled and implemented for forage growth data insertion. Primary data experiments with Cynodon, Panicum and Urochloa cultivars were inserted. The databank allowed the generation of sorted lists of forage mean accumulation rates (TMA), average temperature, maximum and minimum (Tmin) temperatures, global incident radiation and day of the year, for each growth period. Simple and multiple linear regressions were made, with climatic variables as regressors and TMA as response variable. The model with Tmin as independent variable was adopted as standard because it stood out for the best values of determination coefficient, Akaike criterion and Bayesian criterion. The models were grouped by the coincidence test in six groups. The models have different estimating capacities for each cultivar. Model calibration using local data can accommodate effects disregarded in its formulation, and enhances potential yield estimative accuracy.

Cryopreservation of boar sperm comparing different cryoprotectants associated in media based on powdered coconut water, lactose and trehalose.

In swine spermatozoa, the damage caused by cryopreservation is more severe than other species, provoking reduced potential for fertilization. Adjustments in the freezing extender composition may be an important alternative to increase its efficiency. The objective of this study was to test the efficiency of different cryoprotectant solutions during cryopreservation of swine semen with a controlled cooling curve. Three cryoprotectant solutions (5% dimethylformamide, 3% glycerol and the combination of these two cryoprotectants) were used in association with three base media (powdered coconut water, lactose and trehalose), constituting nine different treatments. The semen was frozen using a controlled-rate freezer (TK-3000). After thawing, semen was evaluated for total sperm motility, vigor, morphology, plasma membrane integrity and acrosome integrity. Cryopreservation with the controlled curve using an automated system showed satisfactory results, guaranteeing practicality and repeatability for the process of freezing swine sperm. With this curve, the solutions of lactose, trehalose and powdered coconut water associated with glycerol, as well as the solution of coconut water containing dimethylformamide, presented higher quality of sperm compared to the other solutions. Powdered coconut water associated with dimethylformamide appears as a new solution for swine sperm cryopreservation. The freezing controlled curve used in this study allowed standardization of the cryopreservation technique.

Efeito de diferentes formas de congelamento sobre raízes de mandioca

The physical-chemical, sensory and microbiological characteristics during storage of cassava roots subjected to different freezing methods were evaluated. The roots were physically characterized, processed, packaged in LDPE packages with 100 µm of thickness and subjected to different treatments: freezing and storage at –18°C; freezing and storage at –80°C; and freezing with liquid nitrogen and storage at –80°C. The storage period was 31 days. The product subjected to all treatments had acceptable levels of pH, titratable acidity, soluble solids, ratio, ascorbic acid and time for cooking as well as the counting of evaluated microorganisms. In treatments freezing and storage at –18°C, freezing with liquid nitrogen and storage at –80°C cassava roots were sensory accepted throughout the storage. Despite the good results presented in storage of cassava roots subjected to freezing with liquid nitrogen and storage at –80°C, further studies are suggested regarding requirements and costs for the use of this technology at the producer level. The temperature of –18°C is sufficient to keep the product with appropriate characteristics for at least 31 days.

Avaliação de genótipos de mandioca industriais em área de Cerrado do Noroeste de Minas Gerais

A avaliacao agronomica de cultivares e passo inicial para a determinacao do potencial de cultivo de uma cultura em determinado local. Entretanto, ainda nao foram desenvolvidos estudos sistematicos visando a determinacao do potencial produtivo de diferentes genotipos de mandioca para industria, na regiao de Unai, Minas Gerais. Por isso, o objetivo deste estudo foi avaliar, por duas safras, 12 genotipos-elite de mandioca para industria de farinha e fecula, em area de Cerrado da Regiao Noroeste de Minas Gerais, no municipio de Unai. Os experimentos foram conduzidos entre novembro de 2010 e maio de 2012 (safra 2010/2012) e entre novembro de 2011 e maio de 2013 (safra 2011/2013), em area experimental da Escola Agricola de Unai. Aos 12 meses apos o plantio, nas duas safras, efetuou-se a poda da parte aerea, a 10 cm do solo, de todos os genotipos. Aos 18 meses apos o plantio dos experimentos, os genotipos foram avaliados quanto aos caracteres peso da parte aerea, produtividade de raizes, percentagem de amido nas raizes e foi estimado o rendimento de amido. Os dados foram submetidos a analise de variância individual e conjunta e ao teste de agrupamento de medias. Os resultados revelaram que os genotipos diferiram quanto aos caracteres avaliados, sendo que todos apresentaram caracteristicas com potencial para cultivo, nas condicoes locais de avaliacao, como elevada produtividades de raizes, elevado peso da parte aerea, elevados teores de amido nas raizes e elevado rendimento de amido, com destaque para o acesso BGMC 996.

Relationships between soil organic matter pools and nitrous oxide emissions of agroecosystems in the Brazilian Cerrado

In the Brazilian Cerrado, despite the increasing adoption of no-till systems, there are still extended areas under conventional soil management systems that reduce soil carbon (C) and nitrogen (N) stocks and increase the emissions of greenhouse gases, such as nitrous oxide (N2O). Conservation agroecosystems, such as no-till, have been proposed as a strategy to mitigate agriculture-induced climatic changes through reductions in N2O emissions. However, the relationship between organic matter and N2O emissions from soils under different agroecosystems is not yet clear. This study hypothesized that agroecosystems under no-till promote an accumulation of labile and stable SOM fractions along with a reduction of N2O emissions. This study evaluated the effects of crop-rotation agroecosystems: i) on C and N pools and labile and stable SOM fractions; ii) on cumulative N2O emissions; and iii) on the relationships between SOM fractions and N2O emissions. The agricultural systems consisted of: (I) soybean followed by sorghum under no-tillage (NT1); (II) maize followed by pigeon pea under no-tillage (NT2); (III) soybean under conventional tillage followed by fallow soil (CT); (IV) and native Cerrado (CER). After CT for 18years, following the replacement of CER, the soil C stock in the 0-20cm layer was reduced by 0.64tha-1year-1. The no-till systems were more efficient in accumulating labile and stable C fractions with values close to those observed under CER, and were directly related to lower soil N2O emissions. The cumulative pattern of N2O emissions was inverse to that of the following SOM fractions: microbial biomass carbon, permanganate-oxidizable carbon, particulate organic carbon, inert carbon, and humic substances. Based on principal component analysis, the CT was generally separated from the other land use systems. This separation was strongly influenced by the low C contents in the different SOM fractions and higher N2O emissions promoted by the CT.

Optimization of the roasting conditions of arabica coffee cultivated in the cerrado area of Brazil

RESUMO: O objetivo deste trabalho foi otimizar, por meio do planejamento DCCR (Delineamento Composto Central Rotacional), as condicoes tempo e temperatura de torracao para tres genotipos Coffea arabica L. cultivados no Cerrado, sob condicoes de estresse hidrico controlado, para manter alto teor de solidos soluveis e uma coloracao de torracao aceitavel pelos consumidores. Deste modo, sera possivel conhecer o uso potencial destes genotipos na industria do cafe soluvel. O planejamento DCCR foi realizado com dois fatores (tempo e temperatura) e 11 experimentos, para cada um dos tres genotipos. O teor de solidos soluveis foi determinado com refratometro digital e a coloracao dos graos torrados foi avaliada pelo sistema Agtron. O software livre R foi utilizado na analise de variância e na regressao linear multipla, para a definicao de modelos matematicos de predicao e de parâmetros estatisticos. A selecao do melhor binomio cor-solidos soluveis, que atende a coloracao de 65# a 45# (media clara a moderadamente escura) no sistema Agtron e que fornece o maior valor de solidos soluveis, foi feita pela ferramenta SOLVER do Excel versao 2010. As condicoes de temperatura e tempo de torracao, que mantiveram altos teores de solidos soluveis e que produziram graos torrados com uma coloracao adequada ao consumo, foram 204,8 °C e 10,9 minutos para a cultivar MG 1177; 214,2 °C e 8,8 minutos, para MG 0188; 240 °C e 7 minutos, para Icatu 2944, mostrando o potencial para o consumo tradicional e para a producao de cafe soluvel. ABSTRACT: The aim of this work was to optimize, by way of a rotational central composite design (RCCD), the roasting temperature and time conditions of beans from three Coffea arabica L. genotypes cultivated in the Cerrado, Brazil under controlled water stress conditions, to maintain a high soluble solids content and a roasting colour acceptable by consumers. In this way it will be possible to know the potential use of these genotypes in the instant coffee industry. The RCCD design was carried out with 2 factors (time and temperature) and 11 experiments for each of the three genotypes. The soluble solids contents were determined using a digital refractometer and the roasted bean colour evaluated using the Agtron system. The software R was used in both the variance analysis and in the multiple linear regression to define the prediction mathematical models and the statistical parameters. The Excel SOLVER tool version 2010 was used to select the best colour-soluble solids binomial to provide a colour from 65# to 45# (medium light to moderately dark) on the Agtron system and the highest soluble solids value. The roasting temperature and time conditions that maintained high soluble solids contents and produced roasted beans with an appropriate colour for consumption were 204.8 °C and 10.9 minutes for the cultivar MG 1177; 214.2 °C and 8.8 minutes for MG 0188; and 240 °C and 7 minutes for Icatu 2944, showing the potential for traditional consumption and the production of instant coffee.

Eficiência de regenerantes como indicador de restauração ecológica no Cerrado, Brasil

The objective of this study was to evaluate the efficiency of regenerating as an ecological indicator of restoration in riparian forests in the Cerrado, DF, from January/2012 to January/2013. The restoration experiment contained six treatments with three repetitions each (T1 = Nucleation; T2 = Nucleation + perches; T3 = perches; T4 = planting in rows: lines with fast growing and good covering species and diversity lines; T5 = control with brachiaria; T6 = brachiaria suppression). The percentage of coverage of saplingwas made using the Braun-Blanquet method, and then applied the nonparametric Kruskal-Wallis test. There was a significant difference between the initial and final cover for the T1. The other treatments there was little increase in the coverage of sapling, but not significant, even as in the increase between treatments. There were no differences between treatments when analyzing only the density of sapling, which may be associated with high mortality rate of certain species. Although early, the percentage of coverage of sapling was a good indicator of the ecological restoration process, according with aspects: sensitivity, results, cost, understanding and interpretation, predictability or trend and scale. Thus, it can be concluded that the percentage of coverage of sapling demonstrated efficiency as an indicator.

Óxidos de nitrogênio e CO2 de Latossolo cultivado com milho em sucessão a plantas de cobertura

The objective of this work was to evaluate the effect of two legumes (Crotalaria juncea and Mucuna pruriens), as cover crops, and of natural fallow, as a control treatment, on the emissions of NOx, N2O, and CO2 from an Oxisol cultivated with corn, under conventional and no-tillage systems, in the Cerrado region, in Central Brazil. Variations of CO2 fluxes in the soil were explained mainly by soil humidity and, in the legumes, under conventional system, by soil NH4-N concentration. Plots with legumes under no-tillage system had higher annual emissions of CO2, NOx, and N2O than natural fallow. Results show that the use of legumes as cover crops favors the emissions of NOx-N + N2O-N and CO2-C. However, when considering the potential for mitigation of CO2 and nitrogen oxide emissions from the soil, it is important to evaluate changes in soil carbon and nitrogen stocks.

Cytokine gene expression and molecular detection of Mycobacterium avium subspecies paratuberculosisin organs of experimentally infected mice

Mycobacterium avium subspecies paratuberculosis (MAP) can infect ruminants and remain subclinical for long periods within herds. The identification of organs that are more susceptible to infection and the evaluation of cytokine expression at the site of infection are important to understand the pathogenesis of MAP. In this study, the probability of detection of MAP-DNA and the expression of cytokines in organs of C57BL/6 mice infected intraperitoneally for 120 days were evaluated. Among the evaluated organs, the spleen (85%), colon (75%) and liver (60%) had the highest frequency of positivity. When compared these frequencies between organs, it has been found that the spleen had 1.54 times as likely to be positive in relation to the ileum, and 2.0 times more likely in relation to the Peyers patches. In addition, at 60 days post-infection, the spleen and the liver were responsible for upregulation of IFN-γ , and the ileum by TNF-α and IL-4. The results indicate that the spleen is the best organ for evaluating an experimental infection by MAP, especially in the initial stages of the infection. Moreover, it showed that the spleen, liver and ileum have a direct role in the inflammatory response in experimental models.