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Nitrogen (N) dynamics in plants during their development in agricultural crops has to be well understood in order to design management practices that lead to maximum productivity with minimum N loss from the system. In a labeled fertilizer field study 15N accumulation in different plant parts of mature coffee was observed over time. The objective was to ascertain the time of greatest crop N demand as a scientific basis for designing fertigation schedules. Coffee plantations of central Brazil are routinely fertigated only with extremely high applications of N. Good coffee bean production should be sustainable by applying lower N quantities at those frequencies designated by additional scientific criteria. The experiment was carried out over a complete coffee cropping cycle (2008/2009) in a field of low soil fertility in the Brazilian savanna “cerrado”. Rates of 0, 200, 400, 600 and 800 kg N ha−1 year−1 as 15N-labeled urea were applied via fertigation, divided equally over the year into 26 portions, distributed every 14 days. Changes of N absorption in various plant compartments indicated that fertilizer use could be improved if a lower rate is applied only up to the beginning of fruit maturation, focusing on the stage before fruit filling. This specific stage was found to be the period of greatest N consumption by leaf and fruit. 15N absorption data showed that it is possible to decrease the routine fertilization rate of 600 to a much lower value, of order of 200 kg N ha−1 without decreasing the production of coffee beans. 相似文献
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Isabeli Pereira Bruno Klaus Reichardt Rafael Pivotto Bortolotto Victor Meriguetti Pinto Osny Oliveira Santos Bacchi Durval Dourado-Neto 《Journal of plant nutrition》2015,38(13):2055-2076
Brazil is a major world coffee producer, using increasing quantities of nitrogen (N) fertilizer as the monoculture expands across the savannas. The fate and efficiency of this fertilizer N were evaluated for one complete cropping cycle using 15N tracer, permitting an N balance at harvest. Annual rates of 200, 400, 600, and 800 kg N ha?1 year?1 of 15N-labeled urea and an unfertilized control were applied every 14 days via fertigation. The N concentration, percentage of N derived from fertilizer, quantity of N derived from fertilizer, and percentage of nitrogen derived from fertilizer per N rate was assessed for 8-year-old coffee trees. The most efficient N use was with 200 kg ha?1 year?1 because it presented the lowest losses and highest N recoveries in the crop. Conversely, the least sustainable rate was 800 kg ha?1 year?1, which presented the greatest losses and the lowest N recovery in the whole plant. 相似文献
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Julio César A Santos Franklin Riet-Correa Ant?nio F M Dantas Severo S Barros Russell J Molyneux Rosane M T Medeiros Durval M da Silva Odací F de Oliveira 《Journal of veterinary diagnostic investigation》2007,19(6):690-694
A disease known as water belly (barriga d'água), characterized by chronic progressive ascites, affects sheep in the semiarid region of northeastern Brazil. The objectives of this investigation were to study the disease and to determine its cause. Only sheep grazing for long periods in pastures where Tephrosia cinerea represents 80% to 100% of the available forage are affected. Most animals die after a clinical manifestation period of some weeks or months, but others recover when they are withdrawn from the pastures or after the first rains. At necropsy, large amounts of liquid were found in the abdominal cavity, and the liver was hard, with an irregular surface. On histology examination, the main liver lesion was chronic periportal and subcapsular fibrosis with bridging. The disease was produced experimentally in 1 sheep by the administration of large amounts of T. cinerea for 232 days. Another sheep, recovered from the spontaneous disease, had clinical signs after the ingestion of large amounts of the plant for 40 days. Seeds and leaves of the plant were examined by gas chromatography-mass spectrometry for the presence of pyrrolizidine alkaloids with negative results. It is concluded that the disease is caused by the ingestion of T. cinerea. 相似文献
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Felisberto Guilherme Schwerz Felipe Umburanas Renan Caldas Dourado-Neto Durval Reichardt Klaus 《Journal of Crop Science and Biotechnology》2023,26(1):27-37
Journal of Crop Science and Biotechnology - Water deficit during grain filling is a key factor on soybean (Glycine max (L.) Merrill) production, but plant response to different water stress levels... 相似文献
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Simone da Costa Mello Rachel Tonhati Dourado Durval Neto Murali Darapuneni 《Journal of plant nutrition》2013,36(16):2126-2140
AbstractLimited information on the agronomic performance of polyhalite (K2SO4.MgSO4.2CaSO4.2H2O) motivated us to establish two field trials in Sao Paulo, Brazil. The objective was to evaluate the comparative responses of tomato to muriate of potash (MOP), sulfate of potash, potassium magnesium sulfate, and polyhalite at different graded doses of potassium (K) application supplying varied amount of secondary nutrients. Under very low soil K conditions, polyhalite resulted in significantly higher marketable fruit yield, and higher foliar and fruit K and sulfur (S) concentrations than other K sources. This was not the case under medium soil K levels, that is, 101?mg?kg?1. Likewise, polyhalite enhanced postharvest residual soil calcium (Ca), magnesium (Mg), and S than other evaluated sources. Depending on soil nutrient status and the cost of polyhalite, tomato farmers of Brazil could consider polyhalite as an option to meet crop K and secondary nutrient requirements. 相似文献
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Important pest species of the Spodoptera complex: Biology,thermal requirements and ecological zoning
Parra Jos&#; Roberto Postali Coelho Aloisio Cuervo-Rugno Johanna Bajonero Garcia Adriano Gomes de Andrade Moral Rafael Specht Alexandre Neto Durval Dourado 《Journal of pest science》2022,95(1):169-186
Journal of Pest Science - In South America, especially in Brazil, four members of the Spodoptera complex, Spodoptera albula (Walker, 1857), S. cosmioides (Walker, 1858), S. eridania (Stoll, 1782),... 相似文献
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Experimental results obtained from a greenhouse trial with common bean (Phaseolus vulgaris L.) plants performed to test model hypotheses regarding the onset of limiting hydraulic conditions and the shape of the transpiration reduction curve in the falling rate phase are presented. According to these hypotheses based on simulations with an upscaled single-root model, the matric flux potential at the onset of limiting hydraulic conditions is as a function of root length density and potential transpiration rate, while the relative transpiration in the falling rate phase equals the relative matric flux potential. Transpiration of bean plants in water stressed pots with four different soils was determined daily by weighing and compared to values obtained from non-stressed pots. This procedure allowed determining the onset of the falling rate phase and corresponding soil hydraulic conditions. At the onset of the falling rate phase, the value of matric flux potential Ml showed to differ in order of magnitude from the model predicted value for three out of four soils. This difference between model and experiment can be explained by the heterogeneity of the root distribution which is not considered by the model. An empirical factor to deal with this heterogeneity should be included in the model to improve predictions. Comparing the predictions of relative transpiration in the falling rate phase using a linear shape with water content, pressure head or matric flux potential, the matric flux potential based reduction function, in agreement with the hypothesis, showed the best performance, while the pressure head based equation resulted in the highest deviations between observed and predicted values of relative transpiration rates. 相似文献
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