The prevalence of norovirus, astrovirus and adenovirus infections among hospitalised children with acute gastroenteritis in Porto Velho, state of Rondônia, western Brazilian Amazon

Although viruses are well-established causes of acute gastroenteritis, few data on the circulation of these pathogens in Porto Velho, state of Rondônia, Brazil, are available. Thus, faecal samples from hospitalised diarrhoeic children, under six years of age, were collected and tested for the presence of norovirus (NoV), adenovirus (AdV) and astrovirus (AstV) from February 2010-February 2012. Specimens were screened by reverse-transcription polymerase chain reaction and viruses were found in 10.7% (63/591) of the cases. NoV, AdV and AstV were detected in 7.8%, 2% and 0.8% of the samples, respectively. NoV infection was observed at all ages and was most prevalent in zero-18-month-old children (84.7%; p = 0.002). A higher incidence of NoV was detected from February-April 2010, when it was found in 52.2% of the cases. Co-infections involving these viruses, rotavirus and enteropathogenic bacteria were detected in 44.4% (28/63) of the children with viral diarrhoea. Nosocomial infections were demonstrated in 28.6% (18/63) of the cases in which viruses were detected. The present paper reports, for the first time, the circulation of NoV and AstV among the paediatric population of Porto Velho and it contributes to our understanding of the roles of these pathogens in gastrointestinal infections.

Potential of grasses and rhizosphere bacteria for bioremediation of diesel-contaminated soils

The techniques available for the remediation of environmental accidents involving petroleum hydrocarbons are generally high-cost solutions. A cheaper, practical and ecologically relevant alternative is the association of plants with microorganisms that contribute to the degradation and removal of hydrocarbons from the soil. The growth of three tropical grass species (Brachiaria brizantha, Brachiaria decumbens and Paspalum notatum) and the survival of root-associated bacterial communities was evaluated at different diesel oil concentrations. Seeds of three grass species were germinated in greenhouse and at different doses of diesel (0, 2.5, 5 and 10 g kg-1 soil). Plants were grown for 10 weeks with periodic assessment of germination, growth (fresh and dry weight), height, and number of bacteria in the soil (pots with or without plants). Growth and biomass of B. decumbens and P. notatum declined significantly when planted in diesel-oil contaminated soils. The presence of diesel fuel did not affect the growth of B. brizantha, which was highly tolerant to this pollutant. Bacterial growth was significant (p < 0.05) and the increase was directly proportional to the diesel dose. Bacteria growth in diesel-contaminated soils was stimulated up to 5-fold by the presence of grasses, demonstrating the positive interactions between rhizosphere and hydrocarbon-degrading bacteria in the remediation of diesel-contaminated soils.

Effects of genetics and environment on isoflavone content of soybean from different regions of Brazil

The effects of genetics and environmental factors on isoflavone content of soybean (Glycine max L.) cultivars grown in different locations in Brazil in 1993/94 were evaluated. Seeds of different cultivars were analised by high performance liquid chromatography (HPLC). In Rio Grande do Sul (RS), Paraná (PR), and Mato Grosso do Sul (MS) States, a significant difference in the isoflavone total content average of the cultivars IAS 5 and FT-Abyara (163.9, 116.4 and 79.5 mg/100 g, respectively) was observed. In general, IAS 5 contained higher isoflavone than FT-Abyara. Cultivars IAS 5 and FT-Abyara grown at Vacaria, RS (28°30' S latitude) with temperature average of 19°C, had the highest isoflavone concentrations (218.7 and 163.8 mg/100 g, respectively). In Palotina, PR (24°27' S latitude), where temperature average was 24°C, the isoflavone concentrations were 105.9 and 86.8 mg/100 g, respectively. The lowest isoflavone contents were observed for FT-Estrela and FT-Cristalina, (27.6 and 46.5 mg/100 g, repectively) at Rondonópolis, MT (16°20' S latitude), where the temperature was 27°C.

Effect of phosphorus and potassium on yield and on agronomical characteristics of cotton

With the objective of studying the effect of increasing phosphorus and potassium doses on the agronomical and technological characteristics of the cotton (Gossypium hirsutum L.), cultivar IAC 20, an experiment was carried out during 1994/95 on a Red-Dark Latossol at the Embrapa-Centro de Pesquisa Agropecuária do Oeste (CPAO) in Ponta Porã, MS, Brazil. A randomized bloch design was used in a 3 x 5 factorial arrangement with four replications. The doses were 30, 60 and 90 kg ha-1 of P2O5, applied as triple superphosphate, and 0, 30, 60, 90 and 120 kg ha-1 of K2O as KCl. The K2O doses used had a significant influence on the seed cotton yield, plant height and weight of 100 seeds and of bolls.

Matriconditioning integrated with gibberellic acid to hasten seed germination and improve stand establishment of pepper and tomato

Emergence and stand establishment of tomato (Lycopersicon lycopersicum (L.) (Karsten ex Farw) and pepper (Capsicum annus L.) seeds are often slow and erratic, particularly under stress conditions. Field emergence trials sometimes have not responded to priming in pepper. This study examined the combined effects of matriconditioning and gibberellin application on the germination and stand establishment of pepper and tomato seeds. Pepper and tomato seeds were conditioned with a solid carrier, Micro Cel E, in the presence of gibberellic acid (GA) for 1, 2 , 3 and 4 days at 15 and 25ºC. The results showed that, in all cases, even under stress conditions, the combination of matriconditioning with GA was effective in improving germination and emergence of pepper and tomato. The germination time was, in average, reduced by 2 to 3 days by primed seeds. Thus, matriconditioning, during which germination is suspended, provides an unique means to rapidly and efficiently digest the endosperm by GA-induced enzymes and reduce the mechanical restraints of endosperm thus providing energy to start and sustain embryo growth.

Identification of zygotic and nucellar seedlings in polyembryonic mango cultivars

The objective of this work was to evaluate the occurrence of polyembryony in the mango cultivars Manila and Ataulfo, and to determine whether seedlings cultured in vitro are zygotic or nucelar. Percentage of polyembryony was calculated and the number of embryos in 100 seeds of each cultivar was recorded. 'Manila' exhibited 97% polyembryony with 3.4 embryos per seed, while 'Ataulfo' had 95% polyembryony with 3.2 embryos per seed. Later, 20 seeds of each cultivar were established in vitro, and it was analyzed those in which all embryos germinated (12 seeds from 'Manila' and 7 from 'Ataulfo'). DNA was extracted from seedling leaf tissue, and its origin was identified with 14 RAPD primers. The polymorphic markers recognized the seedlings of sexual origin in seven of nine 'Manila' polyembryonic seeds, and in four of seven 'Ataulfo' ones. Also, in polyembryonic seeds not all zygotic seedlings were produced by small embryos located at the micropyle.

Influence of the temperature in germination of seeds of jabuticaba tree

The jaboticaba tree (Myrciaria spp.) is originated from the center-south of Brazil and presents different types. It's a medium size tree, with tendency to form a crown with great number of branches. A characteristic considered as limitant for the commercial crop is the great juvenility, advicing producing good rootstocks of seedlings and graft wanted varieties, and other vegetative processes. With the purpose of evaluating the effect of temperature on germination of three clones of jaboticaba tree, was carried out a laboratorial research. It was observed influence of the temperature on germination. The highest percentage of germination was obtained at low temperature (15ºC and 20ºC). When it was used the temperature of 35ºC, two clones had only 8% of germination, while the other one was verified 35%. These values show the possibility of the ocurrence of variability among the clones of jaboticaba tree.

Efficiency of pneumatic and horizontal perforated disk meter mechanism in corn no-tillage seeders in soil with different mobilization reports

This work objectified to evaluate the efficiency of two meter mechanism of corn seeds when submitted to different forward speed and soil management system during the non-tillage seeding. It was used a factorial design in randomized blocks. The factors whose effects were examined were related to the seeders with pneumatic and horizontal disk meter mechanisms for the distribution of the seeds, to the set tractor-seeder forward speeds (4.4; 8.0 and 9.8 km h-1), and to the soil management system considering the corn no-tillage seeding over minimum tillage with chisel plow and the no-tillage system for the seeding of oat culture (Avena strigosa Schreb). It was verified that the forward speed didn't influence the initial and final stands of plants but it interfered in the regularity of longitudinal distribution of plants. The smallest speed provided the largest percentile of normal spacing between plants. The pneumatic meter mechanism presented better performance than the horizontal disk perforated in the longitudinal distribution of plants. About corn productivity aspect it's indifferent the recommendation of use for pneumatic and perforated horizontal disk meter mechanism of seeds.

Growth, nodulation, and yield of soybean and associated weeds as affected by weed management

Two field experiments were conducted at the experimental farm of the National Research Centre at Shalakan, Kalubia Governorate, Egypt, during 2006 and 2007 seasons, to study the effect of three pre-emergence herbicides, prometryn [at the rate of 0.75, 1.5 and 2.25 kg ha-1], oxadiargyl [at the rate of 240, 480 and 720 g ha-1] and butralin [at the rate of 1.20, 2.40 and 3.36 kg ha-1], two hand hoeing treatments and a nonweeded check, on weed infestation, nodulation, growth, yield and yield attributes of soybean plants. Two hand hoeing treatments resulted in the highest weed depression expressed as the lowest fresh and dry weights of broadleaved, grassy and total weeds. The reduction percentage in weed dry matter compared to the nonweeded treatment was 98.3, 92.64 and 96.9% in broadleaved, grassy and total weeds, respectively. Application of the three herbicides at higher or recommended doses significantly reduced fresh and dry weight of the weeds compared to the nonweeded treatment. The results indicated that all the three herbicides at rates higher than the recommended markedly decreased the number, fresh and dry weight of nodules as well as root, shoot and total dry weight plant-1, while application of two hand hoeing treatments significantly increased these traits. Two hand hoeing treatments and pre-emergence herbicides at the recommended rates markedly increased soybean yield and its attributes. Two hand hoeing treatments gave the highest values of number of pods per plant-1, weight of pods per plant-1 and number of seeds per plant-1 by 140.7, 150.0 and 59.8%, respectively, compared to the nonweeded treatment. On the other hand, oxadiargyl at the recommended rate (480 g ha-1) was the best treatment for promoting seed yield (g plant-1), seed yield (kg ha-1) and biological yield (g plant-1) compared to the nonweeded treatment by 87.3, 85.0 and 88.2%, respectively. Prometryn at the rate of 1.50 kg ha-1, followed by two hand hoeing treatments, produced the highest shoot and seed protein percentage as well as seed oil percentage, compared to the other weed control treatments.

Effect of desiccation and salinity stress on seed germination and initial plant growth of Cucumis melo

Smellmelon, an annual invasive weed of soybean production fields in the north of Iran, reproduces and spreads predominately through seed production. This makes seed bank survival and successful germination essential steps in the invasive process. To evaluate the potential of Smellmelon to invade water-stressed environments, laboratory studies were conducted to investigate the effect of desiccation and salinity at different temperatures on seed germination and seedling growth of Cucumis melo. Seeds were incubated at 25, 30, 35 and 40 ºC in the darkness in a solution (0, -0.2, -0.4, -0.6, -0.8, 1 and 1.2 MPa) of a salt (NaCl), and in a solution (0, -2, -4, -6, -8, -10, -12 bar) of PEG-6000 (Polyethylene glycol), in two separate experiments. The results showed that the highest percentage and rate of germination occurred at 35 ºC in salt concentrations of 0, -0.2, -0.4 MPa and PEG concentrations of 0, -2, -4 bar. Increasing the concentration of salt (NaCl) and PEG limited germination, seedling growth and water uptake but increased the sodium content in the seedlings. No significant difference was observed among 0, -0.2 and -0.4 MPa of NaCl and among 0, -2 and -4 bar of PEG concentration at 35 ºC. The negative effects of PEG were more than those of NaCl on germination percentage and germination rate. Increased stress levels lead to reduction of root and shoot length, and SVL of seedlings. Na+ content of seedling decreased with limited seedling growth of C. melo.

Allelopathic action of parthenium and its rhizospheric soil on maize as influenced by growing conditions

Biosynthesis and subsequent release of allelochemicals by a plant into the environment is supposed to be influenced by its growing conditions. To ascertain what will be the allelopathic action of plant parts and rhizospheric soils of parthenium (Parthenium hysterophorus) growing at various farm locations with varied growing conditions, germination and seedling growth of maize hybrid (DK 6142) were assayed by sowing its seeds in petri plates lined with filter paper and pots filled with soil. Minimum germination percentage (30.0%), germination index (2.01), germination energy (36.3), seedling length (3.3 cm), seedling biomass (10 mg) and seedling vigor index (99.0) of maize were observed in leaf extract followed by fruit and whole plant extracts of parthenium growing near the field border. Rhizospheric soil collected underneath parthenium growing near a water channel caused maximum reductions in germination index (30.8%), germination energy (40.6%), seedling length (32.6%), seedling biomass (35.1%) and seedling vigor index (34.3%) of maize compared with that soil without any vegetation. Phytotoxic inhibitory effects of both parthenium plant and rhizospheric soil were more pronounced on maize root than its shoot growth. The higher suppressive action against germination and seedling growth of maize was probably due to higher total phenolic concentrations (6678.2 and 2549.0 mg L-1) and presence of phenolic compounds viz., gallic, caffeic, 4-hydroxy-3-methoxy benzoic, p-coumaric and m-coumaric acids; and ferulic, vanillic, syringic and m-coumaric acids in aqueous leaf extract of parthenium uprooted near the field border and its rhizospheric soil collected near a water channel, respectively.

Effect of zone and crops rotation on Ischaemum rugosum and resistance to bispyribac-sodium in Ariari, Colombia

The objectives of this research were to evaluate (1) weed species presented in rice fields in relation to the geographical zone and crop rotation and (2) the resistance level of Ischaemum rugosum to the herbicide bispyribac-sodium. For the first objective, were sampled 79 commercial fields of rice to establish weed density, coverage, and rotation system in the evaluated fields with record of bispyribac-sodium application of at least five years. To reach the second objective, the seeds were collected from plants in commercial fields with different control levels of bispyribac-sodium herbicide. Seeds were germinated in trays under controlled conditions. When plants presented three leaves these were treated with bispyribac-sodium at different doses. Percentages of control and dry weight of plants were evaluated 12 days after treatments (dat). Dominant species in evaluated fields was I. rugosum, with a frequency of 100%, presenting escapes to different chemical commercial treatments. No significant differences were recorded between rotation systems, nevertheless, the most of I. rugosum population was found in the system rice-fallow-rice. The response of applications at different concentrations allows concluding that 65% of samples had resistance at different degrees reported as indexes from 2 to 42 which are related to rotation systems.

Levels of nutrients and grain yield of maize intercropped with signalgrass (Brachiaria) in different arrangements of plants

Competition between maize and signalgrass can economically cripple the intercropping by the reduced yield of maize and dry matter content of the forage. In seeking to define plant arrangements which make this system more efficient, this research was held with the objective of assessing the effects of interference of densities of signalgrass (Urochloa Brizantha) on nutrition and on maize grain yield. Two field experiments were conducted in a randomized block design with four replications. Treatments were arranged similarly in both experiments, in a 2 x 4 factorial design, the first factor being the dose of Nicosulfuron herbicide applied (0 and 8 g ha-1) and the second factor being the forage seeding rates (0, 2, 4 and 6 kg of seeds per hectare). The interference of signalgrass reduced foliar nitrogen, potassium and phosphorus content in maize plants intercropped with the forage. Higher values of grain yield were observed with the reduction of the spacing and the application of the recommended herbicide underdose (8 g ha-1). It was concluded that, regardless of the seeding density of U. Brizantha, reducing the maize seeding inter-rows spacing, combined with the application of an underdose of Nicosulfuron, caused a positive effect by reducing the initial forage growth, resulting in less interference of Urochloa brizantha on nutrient uptake by the maize plants and grain yield of the crop.

Evolution of Ryegrass Seed Banks Depending on Soil Tillage and Crops

The seed bank is characterized by the amount of seeds and other viable reproductive structures in the soil and it is changed by the input and output of seeds, being classified by its permanence in the soil as transient or permanent. The tillage and crops used decisively influence this dynamic and more disturbed areas tend to have richer seed banks. The purpose of this study was to test different soil tillage and crop systems, aiming to reduce or eliminate the ryegrass in the area. The experiment was conducted from 2010 to 2012. In the first year, the effect of chemical tillage was assessed, compared to the area without tillage. From the second year on, in the area that received chemical tillage, the second experiment was installed, where it was assessed the effect of soil tillage and crop rotation in the ryegrass seed yield. The soil tillage treatment was chisel plow and non-chisel plow. The crop rotation was: fallow/soybean; wheat/soybean; black oat/maize. The samples of soil were taken three times a year and split in 0-5, 5-10, 10-15 and 15-20 cm. After sampling, the seeds were separated from the soil and sterilized. Afterwards, germination and tetrazolium test were conducted. In the same plots used for soil sampling, the emergence flow of ryegrass was assessed in the winter 2011 and 2012. In the first year it was observed that chemical tillage had considerably reduced the amount of ryegrass in the soil. The crop rotations used were more effective than soil tillage in reducing the seed banks in the soil. The rotation oat/maize and wheat/soybean, in only two years, practically zeroed the ryegrass seed banks in the area.

Effect of light and temperature on germination and early growth of Vochysia tucanorum Mart., Vochysiaceae, in cerrado and forest soil under different radiation levels

Vochysia tucanorum Mart. (Vochysiaceae) is a very widely distributed species in the cerrado and forests in Brazil, from the State of Bahia to Paraná. Its seed germination was analysed under eight treatments using different conditions of light and temperature. Up to 73 days, at least ca. 93% of the seeds germinated in all treatments, except under alternating temperatures of 35°/10°C (62%). Light enhanced germination, except under constant temperature of 25°C when seeds are not photoblastic. At this temperature, the highest percentage of germination was found. Initial vegetative growth was analysed by comparing the effects of shading, by means of different percentages of full daylight (100%, 45%, 10.6%, 4.8%), and soils from cerrado and forest. During 123 days, no mortality was recorded and cotyledons persisted on the seedlings of all treatments. In general, the seedlings of V. tucanorum were found to be more or less indifferent to the soil from cerrado or forest and shading seems to promote height increment. However, total dry mass was larger under a radiation of 45% full daylight and smaller under extreme conditions (100% or 4.8% full daylight).