947 resultados para períodos de semeadura
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The aim of this work was to evaluate the effect of a millet-soybean rotation, during the implantation phase of no-tillage system on the physical properties of a Nitossolo Vermelho distroférrico and the dry mass production of millet and the productivity of soybean. The experimental design used was a randomized blocks, in a split splot arrangement, with four replications. The parcels was constituted by three sowings (E1, E2 and E3) and the subparcels was constituted by harvests, where each harvest handling was: M1 - harvest each blooming and covering withdrawal; M2 - harvest each blooming and covering permanency; M3 - only in the first harvest on blooming and covering withdrawal; M4 - only in the first harvest on blooming and covering permanency, and M5-free growing, with no harvest. Samples were collected from three soil layers: 0-0,05, 0,05-0,10 and 0,10-0,20 m. The E2 showed smaller values of soil density and larger values of total porosity. The E3 resulted in smaller values of flocculation degree and mean weight diameter of the aggregates. The E3 showed smaller production of dry mass.
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The sowing of soybean out of the conventional period is an option for the production of seeds with high physiological quality. On the other hand, this fact makes necessary the search for cultivars adapted to new environmental conditions. Therefore, additional research is needed to supply more information to producers related to the choice of the most suited cultivars with regard to high seed quality. This research was conducted in Selvíria, MS, Brazil in which the cultivars FT-2000, FT-Inaê, Embrapa 20 (Doko RC), CAC-1, IAC-17, IAC-18, IAC-19, IAC-8-2, FT-101, FT-109, MT/ BR 45 (Paiaguás), MT/BR 50 (Parecis), MT/BR 52 (Curió), MT/BR 53 (Tucano), MT/BR 47 (Canário), MT/BR 49 (Pioneira), BRSMT Uirapuru, BR Emgopa 314 (Garça Branca), MG/BR 46 (Conquista), FT-Estrela, FT-Cometa, Dourados, JAB-11, BR 9 (Savana), FT-Abyara, Embrapa 30 (Vale do Rio Doce), Embrapa 9 (Bays), Embrapa 31 (Mina), IAC-16; IAS 5, EMGOPA-304, and IAC-Foscarin 31 were studied. These cultivars were sown on June 5, 1998, and evaluated both for agronomic characteristics and the physiological potential of the seeds. The experimental units were arranged in the field according to a randomized complete block design with five replicates. The cultivars more adapted to the climatic conditions were Parecis, Bays, CAC-1, Garça Branca, Paiaguás, Pioneira, and IAC-16. It was concluded that winter sowing should start at the beginning of May, with water supply, since June was found to be too late.
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This study correlated the solid preoperative fasting periods with plasma glycemia, serum cortisol, condition clinic and acid-base balance in dogs submitted to inhalation of general anaesthesia. Eight adults, animals were distributed into three groups in accordance with solid preoperative fasting: group 1 (12 hours), group 2 (18 hours) and group 3 (24 hours). Gastric emptying was observed and following this animals were submitted to the same anesthetic procedure. Heart and respiratory rate, rectal temperature, capillary refill time, percent hydration and noninvasive arterial pressure determined before and after Acepromazine and every 10 minutes during anaesthesia, included ETCO 2; values blood gas (pH, PaCO 2, PaO 2, HCO 3, TCO 2, SaO 2, BE), glycemic and serum cortisol were analyzed before MPA and each 30 minutes during anaesthesia. In recovery anaesthetic, glycemia and serum cortisol were repeated. During anaesthesia there were little cardiovascular and respiratory alteration not having interference of the preoperative fasting periods. Animals with 12 hours of the preoperative fasting showed a higher rise in glycemia levels than others groups in recovery anaesthetic. Serum cortisol wasn't influenced by fasting. Solid preoperative fasting independent of the duration describe a discreet respiratory alkalosis. All animals showed good clinical condition in all three groups. Solid preoperative fasting of the 18 hours is recommended to ensure a complete absence of the solid food contents in stomach.
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Economically, onion is the third more important vegetable in Brazil. As a consequence of the increasing by use of new hybrid varieties, the nutritional management of the crop needs to be adequately known. This research was carried out in São José do Rio Pardo, São Paulo State, Brazil, from March 7 to August 8, 2004. The objective was to quantify, under field conditions, the accumulation of macronutrients by onion cultivars established by direct sowing. The experimental design was in randomized blocks with three replicates. The cultivars studied were Optima and Superex. Samples were taken at 30, 50, 70, 90, 110, 130 and 150 days after sowing. With population of 354,000 plants ha -1 and productivity estimated in 64.8 t ha -1, 'Optima' extracted on 150 days after sowing: 78.77, 13.04, 75.77, 59.09, 11.70 and 24.38 kg ha -1 of N, P, K, Ca, Mg and S, respectively, and 'Superex', for the same plant population, and productivity at 72 t ha -1, 64.68, 10.33, 68.28, 65.58, 13.03 and 24.74 kg ha -1 of N, P, K, Ca, Mg and S, respectively. The Optima hybrid exported through its bulb about 49.17% of N, 60.60% of P, 61.16% of K, 41.15% of Ca, 43.56% of Mg, and 47.18 of S, the equivalent to 38.73, 7.90, 46.34, 24.32, 5.10 and 11.51 kg ha -1, respectively. The Superex hybrid exported through its bulb about 44.29% of N, 55.85% of P, 62.54% of K, 35.71% of Ca, 31.82% of Mg, and 48.80% of S, the equivalent to 28.65, 5.77, 42.70, 23.42, 4.15, and 12.07 kg ha -1, respectively.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This study was carried out to evaluate the effects of surface application of lime rates on soil chemical attributes and soybean yield in a no-tillage system. It was installed a field experiment in a factorial 2×4, and the factors were: two types of lime (calcitic and dolomitic); four rates (0.0 - 0.5 - 1.0 and 1.5 t ha-1 of CaCO3), in a completely randomized blocks experimental design, with four replications. The experiment was located in Matupá, Mato Grosso State, Brazil, being the work developed between November 2006 and May 2007. The evaluations were chemical attributes in the soil layers (0,0-2,5 cm, 2,5-5,0 cm and 5,0-10,0 cm), and the productive characteristics of soybean. Application of lime increased the soil pH (CaCl 2), the exchangeable Ca and Mg, the effective CEC and the base saturation only in the soil surface layer. The two limes were different only for Ca and Mg values in the first layer of soil, and only for the Mg values in the layer of 2,5-5,0 cm. The surface liming in no-tillage system did not change soybean yield.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The objective of this work was to study the morphological and physiological characteristics of the wheat flag leaf as affected by increasing sowing densities and plant growth regulators application. The experimental design was a split-plot with completely randomized blocks and four replications. Plots were consisted by four sowing densities (30, 50 70 and 90 plants m-1) and the split-plots by plant growth regulators: a product composed by auxin+gebberellin+cytokinin (Ax+GA+CK), Trinexapac-Ethyl e (Ax+GA+CK) + Trinexapac-Ethyl, and a control without application. Dry mass accumulation, plant height, morphological characteristics, SPAD index, nitrogen and photosynthetic pigments contents in the flag leaf were determined. The increase in the sowing density resulted in lower dry mass accumulation and SPAD index of the flag leaves. Trinexapac-Ethyl caused increase in the SPAD index, but the chlorophyll content of the flag leaf was reduced. The SPAD index values were more correlated with the nitrogen than the chlorophyll contents. Ax+GA+CK did not affect flag leaf characteristics in wheat plants.
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Mechanical sugarcane harvest without burning and continuous straw on the soil surface may affect the Rottboellia exaltata infestation dynamics in sugarcane fields. Three greenhouse experiments were conducted with the aim of studying the effects of sowing depth (0, 2.5, 5, 7.5, and 10 cm), amount of sugarcane straw on the soil surface (0, 5, 10, and 15 ton ha-1), and residual herbicide (clomazone, flumioxazin, imazapyr, isoxaflutole, and s-metolachlor) on the emergence of Rottboellia exaltata. For each experiment, a completely randomized design with four replicates was applied. The combination of mulch on soil surface (especially with larger amounts of straw) with deeper sowing depths provides less emergence and mass accumulation of R. exaltata. In bare soil, the sowing depth did not affect the weed dynamics. Clomazone and imazapyr were effective herbicides controlling R. exaltata regardless of the amount of straw on the soil surface. Flumioxazin was also effective in controlling R. exaltata but only under bare soil conditions. Even with 60 mm of accumulated rainfall over the 4 day period after application, the amount of flumioxazin leached to the soil was not enough to ensure the same control observed when applying the herbicide on bare soil.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)