951 resultados para Hordeum vulgare L., produtividade


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The bee Apis mellifera has a great importance because it is the most economically valuable pollinator for crops worldwide, ensuring cross-pollination and increasing fruit yield. Moreover, agriculture increasingly develops chemicals to control weeds, fungi and insect pests to ensure productivity. Insecticides are used on a large scale in the state of São Paulo, in cultures of citrus for control of greening. Applications are usually made by aircraft and as a result of the effect derives a significant mortality is observed in apiaries near the plantations. Honey bees can get in contact with such chemical agent through their activities of water harvesting, plant resins, pollen and nectar. Intoxication resulting from this exposure can be lethal, which is easily detectable, or cause effects on the physiology and behavior of the insect. These, in turn are hardly detectable, such as paralysis, disorientation, behavioral changes, but can compromise the entire social structure of the colony, therefore aimed to study the effects of the insecticide Thiamethoxam behavior of honeybees A. mellifera. Newly emerged individuals and with 10 days of age were tested. Applications of 1 μL de Thiamethoxam, diluted in acetone, were made on the dorsal thorax with a microapplicator. Preliminarily, it was observed LD50 twenty four hours after topical treatment of Thiamethoxam. It was found that the LD50 for newly emerged honeybees is 8 ng/bee and for honeybees with 10 days of age is 18 ng/bee. The behaviors were analyzed 1 hour after application of insecticide at doses corresponding to LD50/100, LD50/50, LD50/10 and LD50, besides the control group. In the test reflex proboscis extension, there was impairment of behavior at doses of 8 and 18 ng/bee workers in newly emerged workers and 10 days of age, respectively. And in locomotor behavior was no change only at a dose of 18 ng/bee workers at 10 days of age... (Complete abstract click electronic access below)

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Pós-graduação em Agronomia (Agricultura) - FCA

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Pós-graduação em Agronomia (Agricultura) - FCA

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Pós-graduação em Engenharia e Ciência de Alimentos - IBILCE

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To achieve high wheat yield, correct management of N fertilization and the use of high yield potential cultivars are necessary. The aim of this study was to evaluate the effects of different application rates and sources of N, applied totally at sowing or in topdressing, on grain yield and yield components of two irrigated wheat cultivars under a no-till system, grown in a Cerrado (Brazilian tropical savanna) region of low altitude. A randomized block design was used in a 5 x 3 x 2 x 2 factorial arrangement with three replications, combining five levels of N (0, 50, 100, 150, and 200 kg ha(-1)), three sources of N (Entec (R), ammonium sulfate, and urea), and two application times (at sowing, near the rows, or in topdressing) in two wheat cultivars (IAC 370 and Embrapa 21). The wheat cultivars had similar grain yields. There was no difference among the sources of N for grain yield and yield components. The N applied totally at sowing did not differ from the traditional application at sowing and in topdressing for production of irrigated wheat in no-tillage. The increase in application rates of N increased the leaf N contents and chlorophyll, plant height, and the number of ears per m(2). Grain yield of the wheat cultivars IAC 370 and Embrapa 21 increased up to the application rates of 134 and 128 kg ha(-1) of N, respectively, regardless of application time and source of N. The positive correlation between chlorophyll leaf content and grain yield in accordance with N fertilization levels indicates that N fertilization in topdressing can be recommended based on SPAD readings of leaf chlorophyll performed at 38 days after wheat plant emergence.

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Strategies of cotton growth as row spacing and use of growth regulator are efficient when the knowledge of crop production potential as well as the amounts of nutrients content. The objective of this study was to evaluate the nutritional status of cotton DeltaOpal cultivar through leaf analysis of macronutrient, chlorophyll index and yield in relation to plant arrangement and managements of the growth regulator. The treatments consisted of plant arrangement: arrangement 1: 88,900 plant ha(-1) and row spacing at 0.9m, arrangement 2: 114,300 plant ha(-1) and row spacing at 0.7m, arrangement 3: 178,000 plant ha(-1) and row spacing at 0.45m; management of growth regulator (mepiquat chloride) at 1.0 L ha(-1) dose, concentration was50g L-1: a-no regulator application; b-single application at 70 days after emergency (d.a.e.); c-split application into four stages (35, 45, 55, and 65 d.a.e.). The reading reviews SPAD chlorophyll, leaf analysis of macronutrients and cotton yield were conducted in three agricultural years 2006/07, 2007/08 and 2008/09, under the experimental design of completely randomized blocks, in a 3x3 factorial scheme totaling up nine treatments with four replications. The reduction of row spacing and increasing plant density gives less absorption of potassium and sulfur by cotton crop. A single application of mepiquat chloride increase calcium leaf content. The split application of mepiquat chloride provides increased SPAD reading index, higher foliar magnesium concentration and highest seed cotton yield.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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Pós-graduação em Agronomia (Agricultura) - FCA

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Nitrogen, along with K, is the most limiting nutrient for sunflower productivity. The objective of this research work was to determine the best level of nitrogen in a fertilization formula for the cultivation of sunflower of the ‘HELIO – 251’ cultivar. The fertilization procedure was that recommended for the state of São Paulo for sunflower crop, except that, in each one of the treatments, N doses were of 50, 70, 90, 110, and 130 kg ha-1 . These treatments were distributed in the field according to a randomized complete block design with 4 replications. The N dose which resulted in the highest grain yield, highest oil content, and plant dry matter was of 100 kg ha-1 . Leaf N content and 1,000 grains weight increased with N doses.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)