Statistics is the main science by which researchers validate the results of scientific work, and the choice of an inadequate statistical method may lead to conclusions that are considered questionable by reviewers. This study had the objective of describing the characteristics of the statistical methods used in the papers published in Acta Scientiarum. Agronomy from 1998 to 2016 as part of a a critical analysis of the journal to pinpoint possible failures in the application of these methods. All scientific articles (n = 1,237) published in the journal were surveyed, of which 54.1% addressed areas of crop production. The mean comparison methods were the most commonly used (75.5%) and, consequently, they represented the highest proportion of errors (60.8%) of the authors in the journal.

Crop rotation improves potato (Solanum tuberosum L.) crops; however, in some cases, it can have some negative effects due to the herbicides previously used in crops under rotation. These effects are the decline in the yield and the appearance of physiological disorders, including cracked tubers, which impair the quality and economic value of the potato. Two field experiments were performed with applications of tembotrione and atrazine, alone or in combination. In the Rio Paranaiba (Minas Gerais State) area, in clay soil, the herbicides were applied at post-emergence in corn (Zea mays L.). After corn harvest and soil preparation, the potatoes were planted. In the Serra do Salitre (Minas Gerais State) area, in the medium texture soil, the herbicides were applied and incorporated into the soil, and the potatoes were planted the day after. No injuries were found in the shoots. Decline in the potato yield was found only in the medium texture soil (Serra do Salitre). Atrazine did not affect the quality of potato tubers. In the two areas, tembotrione promoted cracks in “Atlantic” potato tubers. | A cultura da batata (Solanum tuberosum L.) é favorecida pela rotação de culturas e, em alguns casos, desfavorecida pelos efeitos adversos dos herbicidas utilizados anteriormente nas culturas em rotação. Esses efeitos são redução de produtividade e desordens fisiológicas como, por exemplo, rachaduras de tubérculos, que reduzem a qualidade e valor comercial da batata para consumo in natura ou processamento industrial. Em dois experimentos de campo foram realizadas aplicações de tembotrione e atrazine, isolados ou em mistura. Na área de Rio Paranaíba (Estado de Minas Gerais) em solo de textura argilosa, os herbicidas foram aplicados na cultura do milho (Zea mays L.) em pós-emergência e na área de Serra do Salitre (Estado de Minas Gerais) em solo de textura média, foram aplicados e incorporados um dia antes do plantio da batata. Não foram observadas injúrias na parte aérea das plantas. A produtividade de batata foi reduzida somente no solo de textura média (Serra do Salitre). O atrazine não influenciou a qualidade dos tubérculos de batata. Nas duas áreas o tembotrione causou rachaduras em tubérculos de batata “Atlantic”.

Numerical implementation methods such as the finite element method can be used in machine design to study the dynamic behavior of the plant. Input parameters for using the finite element method should be set based on the geometrical, physical and mechanical system under study. Thus, the aim of this study was to determine the mechanical properties of the rachis of macaw palm in the green maturation stage at an age of 180 days and at fruit maturation. The water content was calculated using the oven method of 105 ± 3°C for 24 hours. The modulus of elasticity for the rachis was determined by means of mechanical compression testing. The Poisson's ratios were determined from the results of the longitudinal and transverse deformation of rachis test bodies. The shear tests were performed in two scenarios. In the first one, a blade was used without a tensioner, and in the second scenario, a blade was fixed with a tensioner, characterized by a chamfer at 45°. It was concluded that the modulus of elasticity of macaw palm rachis in the green maturity stage was higher than the values for the mature stage of ripeness. | Métodos de implementação numérica, como o método de elementos finitos, podem ser empregados em projetos de máquinas a fim de estudar o comportamento dinâmico da planta. Como parâmetros de entrada para utilização do método de elementos finitos, devem ser informadas as propriedades geométricas, físicas e mecânicas do sistema em estudo. Objetivou-se neste trabalho determinar as propriedades geométricas, físicas e mecânicas da ráquis de macaúba, nos estádios de maturação de frutos verdes com idade de 180 dias e maduros. O teor de água foi calculado através do método de estufa de 105 ± 3°C por 24h, as dimensões foram determinadas com o auxilio de trena e paquímetro, as massas e os volumes mensurados, empregando-se balança digital e proveta, respectivamente. O módulo de elasticidade da ráquis foi determinado por meio de ensaios mecânicos de compressão. Os coeficientes de Poisson foram determinados pelas deformações longitudinais e transversais de corpos de provas oriundos da ráquis. Concluiu-se que os módulos de elasticidade das ráquis no estádio de maturação verde foram superiores aos valores para o estádio maduro de maturação.

RESUMO. Existe carência de informação na região tropical sobre a interação entre calcário, fosfogesso (FG) e adubação na fertilidade do solo e seu efeito na produção do feijão-comum. O estudo objetivou determinar o efeito da aplicação anual de PG e calcário e níveis de adubação nos atributos químicos do solo, eficiência de fertilização, componentes de produção e rendimento de grãos do feijão-comum. A pesquisa foi realizada em três safras agrícolas em Latossolo vermelho ácrico. O delineamento experimental foi blocos casualizados em esquema fatorial 4x4. Os tratamentos consistiram na combinação de calcário, calcário + FG, FG e controle (sem corretivo) com quatro níveis de adubação. Em solo argiloso ácido e de baixa fertilidade do Cerrado, o parcelamento da dose de calcário ou calcário + FG com aplicação de 1/3 anualmente em SPD aumenta a produtividade do feijoeiro e a eficiência da adubação, embora a melhoria dos indicadores de acidez do solo não alcance os níveis desejados. A aplicação de fertilizantes solúveis para fornecer quantidades adequadas e equilibradas de nutrientes proporciona ganhos mais expressivos de produtividade e melhoria da fertilidade do solo, em comparação com a calagem superficial, mas a combinação das duas práticas resulta nos maiores benefícios para ambos, planta e solo.

We studied the mineralogical properties and chemical composition of different granites using energy dispersive X-ray spectroscopy coupled with scanning electron microscopy to understand the relationship between granite signatures and soil characteristics, including weathering patterns and soil fertility status. The discriminant analysis (DA) was based on soil physical and chemical properties and was used to differentiate soils developed from I- and S-type granites across contrasting climatic conditions in northeast Brazil. The DA identified the highest values of organic carbon, clay and plant nutrients as key variables to recognize soil profiles derived from I-type granites. In contrast, the greater sand contents and Al saturation distinguished soils developed from S-type granites. These results were related to the mineralogical characteristics of each granite type, such as a high percentage of silica-bearing minerals in the S-type granites. The highest concentrations of K, Ca, Mg, and P in I-type granites were found in feldspars, amphiboles, and apatite. These elements account for the majority of nutrients derived in their soil profiles. However, it seems that the harsh conditions of the humid tropical environment equalized the effect of the rocks on weathering rates-the difference in chemical index of alteration is more extreme in the dry region.

Orange rust caused by the fungus Puccinia kuehnii greatly affects sugarcane and causes millions of tons of losses in production. This condition was first reported in Brazil at the end of 2009. The disease is currently present in most of the countries that produce this crop. The aim of this research was to develop risk maps of P. kuehnii infection using temperature and relative humidity data, provided by 389 automatic weather stations throughout the country. A spatial distribution analysis was carried out to assess the number of daily hours of favorable conditions for spore germination in each region. In the central-south region, where the main sugarcane producing states are concentrated, two distinct periods were observed during the three years studied. Higher favorability occurred from October to April, and lower favorability occurred from May to September. The opposite relation was observed on the coast of the north-eastern region, where conditions were more favorable to the disease from May to September. The validation data were confirmed by the results of Pearson’s correlation between sugarcane orange rust infection under field conditions and the proposed maps. In conclusion, risk maps obtained using data from automatic weather stations could contribute to the monitoring of the risk of infection by sugarcane orange rust.

The objective of the present work was to investigate the antioxidant enzyme activities and the occurrence of lipid peroxidation during storage of J. curcas seeds obtained from fruits at different maturity stages. Seeds extracted from fruits collected at three stages of maturity were used, i.e., yellow, brownish-yellow, and brown (dry fruits). The seeds were subsequently stored for 18 months in Kraft paper bags in a laboratory environment. Initially as well as every three months, the seeds were evaluated for germination and electrical conductivity, and the seed embryos were evaluated for lipid peroxidation; protein content; and superoxide dismutase, peroxidase, and ascorbate peroxidase enzyme activity at the same time points. In general, the seeds from the three stages of fruit maturity did not differ regarding germination throughout the entire period of storage, although a reduction in viability was observed after nine months of storage. The electrical conductivity increased during storage and was greater for the seeds obtained from brown fruits. There was a reduction in protein content and in enzyme activities in the seed embryo, except for superoxide dismutase. No relationship was observed between reduction in seed viability and lipid peroxidation. Thus, J. curcas seeds with high initial quality can be stored under environmental conditions for up to 9, 15 and 15 months for brown (dry), yellow and brownish-yellow fruits, respectively, without a significant reduction in germination but with a reduction in seed vigour.

Pitaya is a fruit that is becoming promising for cultivation around the world due to the quality of its fruits in terms of taste and their peculiar external shape. Because it is a recenttly cultivated crop, information about fertilization is essential to enable its production. In this sense, this study was performed aiming to evaluate different doses of K2O for pitaya cultivation. Hylocereus undatus and Hylocereus polyrhizus were studied under field conditions. Pitayas were cultivated at a 3 × 3m spacing, and four doses of K2O were tested: 0, 50, 100, and 200 g plant-1, with a 2 × 4 factorial arrangement distributed in a randomized block design. The production per plant (kg and number of fruits) was evaluated in the production cycles of 2013/2014, 2014/2015, and 2015/2016. The fruit quality was also evaluated: longitudinal diameter, transverse diameter, mass, soluble solids content, titratable acidity and soluble solids/titratable acidity ratio. Potassium fertilization increased production and provided a better quality of pitaya fruits.K2O fertilization should be from 106.0 to 133.3 g K2O in the first year and 200 g K2O in the second and third years after planting.

The objective of this study was to evaluate the influence of pollinating insects on canola productivity for different commercial hybrids, Hyola 61 and Hyola 433, in Minas Gerais State, Brazil. The studies were conducted at the Fazenda Experimental Água Limpa of the Federal University of Uberlândia. To evaluate the influence of pollination by bees on the production of canola seeds, an experiment was carried out to exclude floral visitors and compare canola seed production following four treatments: (a) autogamy in Hyola 61, (b) autogamy in Hyola 433, (c) open pollination in Hyola 61, with insects having free access, and (d) open pollination in Hyola 433, with insects having free access. Flowers that were available for pollination had 25% and 18.8% heavier pods and 22.5% and 20.6% more seeds per pod in Hyola 61 and Hyola 433, respectively, than those bagged without pollination. The results show that the cross-pollination process, fostered by pollinator visits, positively influenced some parameters related to production, presenting an advantage in relation to canola autogamy in Cerrado Mineiro.

The increasing interest in the commercial exploitation of yacon has demanded adequate technological knowledge for the implantation and management of the crop, including planting periods and cultivation regions that contribute to the satisfactory growth and development of the species. This study was conducted in two different locations, one in a mountainous region and another in a lowland region. In each location, yacon was planted in four different seasons, fall (April), winter (July), spring (September) and summer (December). We collected primary dry matter accumulation data for different parts of the plant and the leaf area at 30 day intervals. We used these values to calculate the following morphophysiological indexes: specific leaf area, leaf area index, tillage growth rate and net assimilation rate. We concluded that planting in the fall in mountainous or lowland sites favoured the growth and development of yacon. Cultivation in mountainous regions, regardless of the planting season, promoted a greater mass accumulation of tuberous roots, which may be reflected in higher productivity. Both fall and winter planting in the mountainous region allows root harvesting at the same time.