Manoel Carlos Gonçalves

Tamanho de amostra e número de repetições para avaliação de caracteres agronômicos em milho-pipoca

Resultados experimentais seguros sao obtidos por meio da utilizacao de adequados tamanhos de amostras e numero de repeticoes. O conhecimento do melhor tamanho de amostra tem relevada importância, quando se deseja reduzir os custos na pesquisa, permanecendo baixos os erros cometidos nas inferencias. A utilizacao de um numero adequado de repeticoes nos experimentos e de fundamental importância para a reducao do erro experimental e consequente aumento da precisao experimental. Objetivou-se, nesse trabalho, avaliar o tamanho de amostra ideal para caracteres de pre-colheita em milho-pipoca e verificar as implicacoes do numero de repeticoes na variância residual em caracteres de produtividade e de qualidade. Foram utilizados os genotipos seguintes: variedade BRS ÂNGELA, hibrido triplo ZELIA, variedade UFV-M2 e populacao avancada do hibrido triplo ZELIA. O delineamento experimental foi o de blocos casualizados, em esquema de parcelas subdivididas, com duas, tres, quatro, cinco e seis repeticoes. As parcelas foram constituidas pelos genotipos e as subparcelas pelo tamanho de amostras (5, 10, 15, 20 e 25) plantas parcela-1. Foi observado que, para avaliar caracteres de pre-colheita podem ser adotadas amostras de 5 a 25 plantas parcela-1, sem afetar a precisao experimental. Com o aumento do numero de repeticoes houve aumento na quantidade de caracteres significativos a 1% de probabilidade, para o efeito de genotipos. Houve maior quantidade de diferencas significativas entre medias de genotipos, para os caracteres de pre-colheita e produtividade, nos numeros de repeticoes acima de quatro. Assim podem ser amostradas cinco plantas na parcela, e utilizar quatro repeticoes.

Milho pipoca consorciado com feijão em diferentes arranjos de plantas

The intercropping of popcorn and bean is an alternative for small farmers, by providing higher profits and a better use of the crop area, besides reducing loss risks. This study aimed to evaluate different popcorn and bean intercropping systems. The experiment was carried out in an experimental field owned by the Universidade Federal da Grande Dourados, in Dourados, Mato Grosso do Sul State, Brazil. The experimental design was randomized blocks, with four replications, with treatments arranged in a split-plot scheme, with plots consisting of two popcorn cultivars (Zelia and BRS Ângela) and subplots consisting of three intercropping systems with popcorn and the BRS MG Pioneiro bean (popcorn + bean in the popcorn row, popcorn + bean between the popcorn rows, and corn + bean in the popcorn row + bean between the popcorn rows), and popcorn under monocropping system. The intercropping systems evaluated did not affect the popcorn yield, and bean sown in the popcorn row + between the popcorn rows resulted in a higher yield. In general, the intercropping between the two species decreased bean yield, however, due to the equivalent area index values, it was 50% to 91% more efficient than the monocropping systems.

Aporte de fitomassa pelas sucessões de culturas e sua influência em atributos físicos do solo no sistema plantio direto

A degradacao fisica dos solos, como a compactacao, reduz a movimentacao de agua e o crescimento de raizes. A estrutura do solo e considerada como uma de suas mais importantes propriedades do ponto de vista agricola, pois a ela estao relacionadas outras propriedades fundamentais nas relacoes solo-planta. Com o objetivo de se avaliar o efeito de culturas de cobertura nos atributos fisicos do solo realizou-se este trabalho em um Latossolo Vermelho Distroferrico, textura muito argilosa, nas safras de 2004/2005 e 2005/2006, na Universidade Federal da Grande Dourados, em uma area ha oito anos sob plantio direto. O delineamento experimental foi em blocos completamente casualizados com tres repeticoes. Foram avaliadas as culturas girassol (Helianthus annuus L.), crotalaria (Crotalaria juncea L.), ervilhaca peluda (Vicia villosa Roth), consorcio de crotalaria e aveia preta (Avena strigosa Schreb) e consorcio de aveia preta, ervilhaca peluda e nabo forrageiro (Raphanus sativus L. var. oleiferus Metzg), sucedendo a soja e como antecessoras do milho. As culturas de girassol, crotalaria e o consorcio aveia preta mais crotalaria proporcionaram maiores teores de carbono orgânico total; os valores de macroporosidade e porosidade total aumentaram na camada superficial enquanto os valores de densidade do solo e de microporosidade foram menores nessa camada. Os agregados foram mais estaveis na camada 0 - 5 cm. Os sistemas de culturas estudados foram eficientes na producao de palha, capazes preservar os atributos fisicos do solo. Os consorcios entre aveia preta+ervilhaca peluda+nabo forrageiro e, da aveia preta+crotalaria possibilitam maior cobertura e permanencia da palha sobre o solo.

Disponibilidade de fósforo em dois latossolos argilosos e seu acúmulo em plantas de soja, em função do aumento do pH

The best P employment, both applied in the culture as the P soil residual, is possible, due limestone use in clayey soils cultivated and fertilized for many years. Aiming at evaluating the pH increase in the soil and the effect of the application of phosphated fertilizer and lime on the sowing on the P availability and its accumulation in soybean plants, two experiments in oxisols, Haplortox (one LVD and the other LVDf), with high fertility levels, were carried out. The experimental design was random blocks, in a 4x2x2 factorial, being four pH levels, two P doses and two limestone doses, with four repetitions. Soybean plants were cultivated in vases up to flowering. The dry mass weight, P contents and accumulation in the area, P content and P remaining in the soil, were evaluated. P availability in soils increased with pH elevation. For the LVDf, there was an interaction between the pH and the P doses, the P contents in the soil increased with the pH and with the P application. For the LVD, there was an interaction between the pH and the doses of lime applied. The P remaining was reduced by the pH increase in both soils. In both experiments, with the pH increase in the soil, there was an increment in the dry mass production and P accumulated. In clayey soils with a high P content, the pH elevation increases the P availability, providing greater soybean dry mass production.

Desempenho agronômico da soja sob diferentes rotações e sucessões de culturas em sistema plantio direto

This work is a part of a long-term project that began in 1997 and which involves grain production based on crop rotation or crop succession systems. The experiment was carried out in the 2005/06 season, in a Dystroferric Red Latosol, in the Agrarian Science Experimental Farm of Federal University of Great Dourados – UFGD, in Dourados, Mato Grosso do Sul, Brazil. The experimental design was in randomized blocks with seven treatments and three replications. In each parcel, 26 rows of soybean were sowed, 36 m long, spaced 0.45 m apart. Treatments consisted of seven systems of rotation or succession, involving species that were sowed alone or mixed with species that preceded soybean, comprising the following treatments: System 1: crotalaria + vetch /soybean; System 2: vetch +oat + turnip/soybean; System 3: sunflower/soybean; System 4: millet/soybean; System 5: corn/soybean; System 6: wheat/soybean; and System 7: oat/soybean. Plant height, insertion height of first pod, number of plant ramifications, number of pods per plant, soybean yield, and mass of 100 grains were evaluated. It was concluded that in a no-tillage consolidated system, various species can be used in rotation or succession with soybean, without affecting the components of the leguminous yield.

Inheritance of soybean resistance to Rotylenchulus reniformis

Genetic inheritance of soybean resistance to Rotylenchulus reniformis was studied by evaluating the phenotypic reaction of soybean plants to the nematode. The resistant (Forrest and Custer) and susceptible (BR96-25619) soybean cultivars used as parents as well as the F1, F2 and F2:3 derived from their crosses were infested individually with 1,000 eggs and vermiform R. reniformis. About 70 days after the infestation, the nematodes were extracted from the roots and the reproduction factors and the numbers of nematodes per gram of roots were estimated, and data were adjusted for genetic models. Results suggested a predominance of additive genetic effects controlling the nematode resistance reaction. Based on mean and variance genetic models, further genetic gains are expected in the crossing Custer x BR96-25619. The effect of genetic dominance is towards susceptibility. The presence of significant epistasis indicates the existence of at least two genes controlling resistance and that they are interacting. The normal continuous distribution of frequencies of the number of individuals in different classes of resistance indicates that the resistance to the reniform nematode is inherited quantitatively.

Análise multivariada integrada para avaliação dos efeitos do manejo pré-abate na qualidade da carne suína

The aim of this study was to investigate the effect of pre-slaughter handling on the occurrence of PSE (Pale, Soft, and Exudative) meat in swine slaughtered at a commercial slaughterhouse located in the metropolitan region of Dourados, Mato Grosso do Sul, Brazil. Based on the database (n=1,832 carcasses), it was possible to apply the integrated multivariate analysis for the purpose of identifying, among the selected variables, those of greatest relevance to this study. Results of the Principal Component Analysis showed that the first five components explained 89.28% of total variance. In the Factor Analysis, the first factor represented the thermal stress and fatiguing conditions for swine during pre-slaughter handling. In general, this study indicated the importance of the pre-slaughter handling stages, evidencing those of greatest stress and threat to animal welfare and pork quality, which are transport time, resting period, lairage time before unloading, unloading time, and ambience.

Seleção de progênies de meio-irmãos de milho para eficiência no uso de nitrogênio

The study aimed to estimate the parameters and the genetic gain in selection of half-sib for nitrogen use efficiency, through simultaneous selection of characters. Two experiments were established, differentiated by nitrogen fertilization, one with proper fertilization (high N) and another in stress conditions (low N). The experiment was using a 10x10 lattice with two replications. In the tests we used 84 different half-sib and 16 witnesses. From the mean squares of analysis of variance in each environment were the estimates of genetic parameters. After the analysis were selected in each environment 17 different half-brothers, through the classical index selection, and verified the repeatability of the progeny in both environments. Observed variability among progenies, determining the potential for population screening for nitrogen use efficiency. The parameter estimates and genetic gains were higher in high N The use of selection index promoted estimates of selection gain of 24.43 and 21.05% for high and low N, respectively, for grain yield. The progenies showed average yield of 13.45 and 19.47% higher than control in high and low N, respectively.

Rotação de culturas e relações com atributos químicos e microbiológicos do solo e produtividade do milho

Soil management practices exert important influence on biological and biochemical properties of soil. This work aimed to valuate the impact of crop rotation on soil biochemical and microbiological attributes, as well and influence on corn crop yield. The experiment was carried out during 2005/06 crop season, in Dourados – MS, Brazil. Experimental design was randomized blocks with treatments established in sub-divided plots with tree replications, which seasons were plots and management systems were sub-plots. Studied seasons were winter and summer and no tillage systems were represented by five crop rotation schemes, which involved the cultures of hairy vetch, bean, oat, forage turnip, soybean, crotalaria, corn, sorghum, pearl millet, sunflower and, in conventional tillage, with corn in winter and with soybean in summer. Native vegetation constituted one treatment and, with conventional tillage, it was used as ecosystem of reference as control for comparison between possible alterations in chemical and microbiological attributes with the establishment of a system more conservationist for soil management. There was a positive correlation among Norg, Corg, Porg and C-BMS contents with chemical attributes of soil fertility, which shows interdependence between chemical and biology of soil. The elimination of native vegetation and the substitution for cultivation system after that reduce the C-BMS. In Cerrado conditions, studied cultivation systems increased phosphorus content in soil. Crop rotation influenced corn yield after the cultivation of determined species as crotalaria and vetch in crop rotation.

Agronomic performance of soybean in different rotations and successions of crops in no tillage system

This work is a part of a long-term project that began in 1997 and which involves grain production based on crop rotation or crop succession systems. The experiment was carried out in the 2005/06 season, in a Dystroferric Red Latosol, in the Agrarian Science Experimental Farm of Federal University of Great Dourados – UFGD, in Dourados, Mato Grosso do Sul, Brazil. The experimental design was in randomized blocks with seven treatments and three replications. In each parcel, 26 rows of soybean were sowed, 36 m long, spaced 0.45 m apart. Treatments consisted of seven systems of rotation or succession, involving species that were sowed alone or mixed with species that preceded soybean, comprising the following treatments: System 1: crotalaria + vetch /soybean; System 2: vetch +oat + turnip/soybean; System 3: sunflower/soybean; System 4: millet/soybean; System 5: corn/soybean; System 6: wheat/soybean; and System 7: oat/soybean. Plant height, insertion height of first pod, number of plant ramifications, number of pods per plant, soybean yield, and mass of 100 grains were evaluated. It was concluded that in a no-tillage consolidated system, various species can be used in rotation or succession with soybean, without affecting the components of the leguminous yield.