Raimundo Wagner de Souza Aguiar

Efeito do dióxido do carbono, temperatura e armazenamento sobre sementes de soja e micoflora associada

The vegetative and reproductive development of the soybean is related to the production technology of good quality seeds which are vigorous and free of pathogens. Thus, this study aimed to evaluate the effect of carbon dioxide (CO2) associated with temperature on mycoflora and seed quality for different periods of storage. The design used was a completely randomized factorial (2 x 3 x 4), at two temperatures (25 and 31 oC), three CO2 concentrations (0.0, 2.5 and 5.0 g CO2 kg-1of seed), and four storage periods (30, 60, 90 and 120 days). According with results, it was observed that carbon dioxide was extremely toxic to the fungi Aspergillus sp., Fuzarium sp., Coletrochium sp. and Penicillium sp., with 100% inhibition at a concentration of 5 g CO2 kg-1 of seed, and at temperatures of 25 and 31 oC. Seed germination and vigor were preserved by the carbon dioxide, with 92% germination after 120 days of storage, while for seeds stored without CO2 at a temperature of 31 oC, germination was 44.66%. The preservation of vigor and germination was dependent on the concentrations of CO2 and on temperature. CO2 may be a viable technology for the preservation of the quality of soybean seeds for seed-processing units in the state of Tocantins.

Dual-path platform (DPP) and enzyme-linked immunosorbent assay (ELISA): Change the sequence of the tests does not change the number of positive dogs for canine visceral leishmaniasis

The Brazilian Ministry of Health determined in 2012 that the official protocol for diagnosis of Canine Visceral Leishmaniasis (CVL) would be the Dual-Path Platform (DPP) for screening, followed by enzyme-linked immunosorbent assay (ELISA) for confirmation. This study evaluated serum samples from 426 dogs from a region in northern Brazil. All samples were tested according to the Official Protocol and the sequence inverting (ELISA followed DPP). Regardless of the protocol adopted, prevalence (14.7%) has not changed. The approach using ELISA followed by DPP state that, the number of positive animals in screening was higher compared to the official protocol. Screen the ELISA test could be more appropriate. Key words: Canine visceral leishmaniasis, Dual-Path Platform (DPP), enzyme-linked immunosorbent assay (ELISA), tocantins.

Enzymatic Activity in Essential Oil-Treated and Pathogen-Inoculated Corn Plants

Bipolaris maydis and Exserohilum turcicum are important fungal pathogens that cause leaf blight in corn whose control have been difficult. Essential oils are a promising and environmentally friendly alternative for disease management, but the mechanisms of action remain poorly studied. Here, we aimed to assess the effect of B. maydis and E. turcicum as well as the essential oil of Morinda citrifolia in the activity of plant defense enzymes in corn plants. Experiments were carried out in a completely randomized design with three replications and six treatments as they follow: (T1): corn plants inoculated with B. maydis; (T2): corn plants inoculated with E. turcicum; (T3): corn plants treated with essential oil of M. citrifolia (0.25%) and inoculated with B. maydis; (T4): corn plants treated with essential oil of M. citrifolia (0.25%) and inoculated with E. turcicum; (T5): corn plants treated with essential oil of M. citrifolia (0.25%); and (T6): corn plants non-inoculated and treated with distilled water. Protein content (PC) and activities of the enzymes ascorbate peroxidase, catalase, chitinase (CHI), peroxidase (POX) and superoxide dismutase (SOD) were assessed. PC was significantly decreased, whereas CHI and SOD activity was higher in T1-T5 compared to T6. T4 and T5 significantly increased POX activity relative to T6. Therefore, our findings suggest that the essential oil of M. citrifolia may play an active role in disease control by activating defense enzymes in corn plants.

Essential oil of Siparuna guianensis as an alternative tool for improved lepidopteran control and resistance management practices

Although the cultivation of transgenic plants expressing toxins of Bacillus thuringiensis (Bt) represents a successful pest management strategy, the rapid evolution of resistance to Bt plants in several lepidopteran pests has threatened the sustainability of this practice. By exhibiting a favorable safety profile and allowing integration with pest management initiatives, plant essential oils have become relevant pest control alternatives. Here, we assessed the potential of essential oils extracted from a Neotropical plant, Siparuna guianensis Aublet, for improving the control and resistance management of key lepidopteran pests (i.e., Spodoptera frugiperda and Anticarsia gemmatalis). The essential oil exhibited high toxicity against both lepidopteran pest species (including an S. frugiperda strain resistant to Cry1A.105 and Cry2Ab Bt toxins). This high insecticidal activity was associated with necrotic and apoptotic effects revealed by in vitro assays with lepidopteran (but not human) cell lines. Furthermore, deficits in reproduction (e.g., egg-laying deterrence and decreased egg viability), larval development (e.g., feeding inhibition) and locomotion (e.g., individual and grouped larvae walking activities) were recorded for lepidopterans sublethally exposed to the essential oil. Thus, by similarly and efficiently controlling lepidopteran strains susceptible and resistant to Bt toxins, the S. guianensis essential oil represents a promising management tool against key lepidopteran pests.

Ethnobotanic Study of Use of Medicinal Plants Utilized in the Quilombola Community of Chapada Da Natividade, Tocantins, Brazil

Article History Received: 5 March 2018 Revised: 11 July 2018 Accepted: 13 July 2018 Published: 17 July 2018

Intercropping of Cowpea with Eucalyptus in Northern Brazil

Intercropping consist in growing two or more species with different vegetative cycles and architectures, simultaneously cultivated in same field and same period of time, not necessarily having been sown at the same time. The objective of this study was to evaluate different populations of cowpea development intercropped with Eucalyptus, in order to determine the number of rows of cowpea generates higher grain productivity. This work was carried out at Universidade Federal do Tocantins, in Gurupi, Tocantins, Brazil. The treatments were arranged for different densities of cowpea rows: eight rows, six rows, and four rows of cultivars BRS Nova Era and BRS Sempre Verde, also a control in conventional cropping. The cowpea sowing occurred after 12 months eucalyptus planting. The evaluated characteristics were Flowering (FLOW), Mass of 100 grain (GM), Number of grains per green pod (NGP), Chlorophyll Index (CI) and Grain yield (GY). The density of eight rows have obtained better results for most characteristics, being the density limiting factor for bean production could unfeasible the intercropping system. The BRS Nova Era responds better on most characteristics, probably for a better adaptation to the environment and hold superior characters than BRS Sempre Verde.

The Efficiency of Noni (Morinda citrifolia L.) Essential Oil on the Control of Leaf Spot Caused by Exserohilum turcicum in Maize Culture

The objective of this work was to evaluate the efficiency of noni essential oil on the control of Exserohilum turcicum, a causative agent of Exserohilum spot in maize culture. In the sanitary test 400 seeds were incubated using the blotter test method. For the transmissibility test, the fragments of damaged leaves of seedlings were removed and put into a potato, dextrose and agar (PDA) culture environment. To verify the pathogenicity, Koch´s postulates were performed. In the phytotoxicity test different concentrations of noni oil were applied in maize seedlings. E. turcicum conidia were submitted to different concentrations of noni oil. In the preventive and curative tests noni essential oils were applied before and after the conidia inoculation, respectively. The results revealed the presence of fungi of the genres Aspergillus, Penicillium, Rhizopus, Fusarium, and Exserohilum in the maize seeds. The pathogenicity of E. turcicum and also the transmission of this fungus from the seeds to the maize seedlings was confirmed. The inhibition of conidia germination was proportional to the concentration increase. The preventive application of noni essential oil was the most efficient on the control of Exserohilum spot.

Susceptibility assessment of watermelon and pumpkin cultivars to potyvirus in Tocantins

Cucurbits cultivation has great importance in the food industry. However, in the main producing regions of curcubits, the increase of cultivation areas has been limited by viral infections. Among the most prevalent viruses there is the Watermelon Mosaic Virus (WMV), Papaya Ringspot Virus (PRSV-W) and Zucchini Yellow Mosaic Virus (ZYMV). The aim of this study was to evaluate the reaction of watermelon genotypes (Crimson sweet and Charleston Gray) and pumpkin (Jacarezinho and Caserta) to isolate watermelon strains in the following cities: Palmas (PYP-12), Gurupi (PYG-14 and PYG-19), Formoso do Araguaia (PYF-6), and Porto Nacional (PyPn-36 and PyPn-39). The experiment was performed in a greenhouse, in a completely randomized design, with 5 testing plants for each repetition to measure the response of these strains to cucurbit genotypes. The inoculated strains were obtained from leaves of watermelon cv Crinson sweet with symptoms The plants were rated by severity of viral symptoms in intervals of four days during 32 days. It was verified that the cucurbit genotypes showed different susceptibility to the viral strains. However, Caserta and Charleston gray were the ones which had greater sensitivity due to their high severity variation among the tested strains. Thus, it can be observed that the reaction among strains depends on the host and this reaction can be antagonistic or synergistic, depending on the mixed infection. Charleston gray watermelon was the most susceptible to most of the viral strains. Thus, this cultivar should be avoided in these regions.

Eficácia de fungicidas associados a inseticidas sobre o crestamento gomoso do caule e produtividade do meloeiro

One of the most important diseases that attack melon (Cucumis melo L.) is gummy stem blight, caused by the fungus Didymella bryoniae, which is highly aggressive under conditions of high temperature and humidity. Thus, the present study aimed to evaluate the efficacy of fungicides associated with insecticides in the control of gummy stem blight in melon plants under naturally infested field conditions. The experiment was conducted as two assays; in assay I, the cultivar Eldorado 300 was used with the treatments of selective and non-selective insecticides mixed with fungicides. For assay II, the hybrid Hibrix was used with part of the same treatments used in assay I. According to the results, the treatments without fungicide and the mixtures of fungicide and selective and non-selective insecticides, with the use of pest and disease monitoring, showed high levels of gummy stem blight incidence and lower values of fruit yield in melon plants. On the other hand, treatments with fungicide or the mixture of fungicide with insecticide showed greater efficiency in controlling the disease, which resulted in higher fruit yield.