957 resultados para Cana-de-açúcar - Efeito do stress
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Agronomia - FEIS
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Pós-graduação em Agronomia - FEIS
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Pós-graduação em Agronomia - FEIS
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Um experimento de campo com diferentes níveis de irrigação e nitrogênio foi conduzido no Centro de Ciências Agrárias da Universidade Federal de Alagoas com o objetivo de determinar a função de produção e as isoquantas de produtividade agrícola da cana-de-açúcar com base nas lâminas de irrigação e doses de nitrogênio (N). A precipitação pluvial efetiva durante o ciclo de produção foi 1.037 mm e a lâmina de irrigação bruta máxima foi 873 mm. A produtividade agrícola ficou entre 118 e 188 Mg ha-1, média de 160 Mg ha-1. Na isoquanta da produtividade agrícola média da cana-de-açúcar, a taxa marginal de substituição de água por N é 0,36 kg mm-1 (na interseção das retas de 25 kg de N ha-1 e 760 mm de irrigação) e infinita (na interseção das retas de 125 kg de N ha-1 e 390 mm de irrigação). A quantidade de água e nitrogênio de menor custo para produzir 160 Mg ha-1 foi 390 mm de irrigação e 112 kg de N ha-1. A regressão polinomial de segundo grau apresentou ajuste médio (r2 = 62%) para a produtividade agrícola em relação às lâminas de irrigação e doses de nitrogênio. A resposta da cana-de-açúcar à adubação nitrogenada aumenta em proporção direta com disponibilidade hídrica do solo.
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Pós-graduação em Química - IQ
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
Potencial produtivo da cana-de-açúcar sob irrigação por gotejamento em função de variedades e ciclos
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This study aimed to evaluate the yield potential of different varieties of sugarcane under drip irrigation in two growth cycles. A trial was set up in October 2006 at Jaú region (São Paulo state, Brazil), in an experimental field with a eutrophic Ultisol. The experiment was conducted in randomized complete blocks with factorial treatment structure 8 x 2, constituted by eight sugarcane varieties and two crop cycles, with six replicates. Stalk productivity (TCH), sugar productivity (TPH), juice quality traits and water use efficiency in relation to stalk productivity were evaluated in each crop cycle. It was observed that varieties of sugarcane respond differently to full irrigation, and this response is influenced by climatic conditions of the agricultural year. In this study, only the first evaluation cycle (plant cane) was decisive to differentiate the performance among the varieties. The varieties IAC91-1099, IACSP96-3060, RB855536, RB867515 and SP85-1115 showed higher agro-industrial yield potential and less consumption of water and can be recommended for the management of production under drip irrigation.
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During the sugarcane mechanized harvester process, the wear of base cutting knives is directly correlated to the quality of the cut made by the machines, and the use of quality control tools important in monitoring this process. Thus, the present study in Ribeirão Preto region aimed to assess the knives cut baseline and damage caused to wear brass knuckles in mechanized harvesting of cane raw sugar, from the viewpoint of statistical quality control (SQC). The wear of the knives was quantified by mass loss and its dimensions, while cutting quality was assessed by cutting height and damage to stumps visually classified according to the level of damage caused. The results showed that the wear of the knives was more pronounced in certain periods of use, but still within control standards. The cutting height was not affected by the wear of the knives, keeping within the limits of desirable quality for operation. Eventually damage the stumps ranged among themselves depending on each face of the cutting knives evaluated, and the predominance of certain classes of damage in each cutting face, but always remained in statistical control.
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In agriculture, the search for higher crop yields based on sustainable soil management has led to a gradual pursuit of knowledge of the variables related to production systems. The identification of the causes of variability of these properties has become a part of strategic planning in the sugar and ethanol industry. This study investigated the spatial variability of iron oxides in the clay fraction and its relationship to soil physical and chemical properties in different sugarcane cultivation systems in the region of Ribeirão Preto, São Paulo State. Two 1-ha plots were outlined in areas with mechanical and manual harvesting systems. Soil samples were taken at 126 points from the 0.00-0.25 m layer in both areas. The mineralogical and chemical data were subjected to geostatistical analyses, to determine the spatial dependence, semivariograms and kriging maps of the properties. To analyze the correlation between the parameters cross-semivariograms were constructed. The spatial variability of chemical properties was greater in areas with mechanical harvesting than burnt harvesting (manual harvesting), whereas the range of the mineralogical properties was largest in the area of green-harvested sugarcane. The properties organic matter, mean crystal diameter goethite had a negatively spatial correlation, while clay was positive correlated with P sorption in the two sugarcane harvest systems.
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The aim of this study was to evaluate the interaction among meteorological variables and yield components of six sugarcane varieties and to establish appropriate varietal management at the Coastal Tablelands of the Alagoas State (Brazil). The sugarcane planting was carried out in September 2005, and three cane harvests were made in November 2006, 2007 and 2008. The experimental design was in randomized block with six treatments consisting of the varieties RB863129, RB867515, RB92579, RB93509, RB931003 and RB951541, with four replications. The growth variables evaluated were number and length of stalks, leaf area index, and productivity of stalks and sugar. On average, the crop water balance showed water deficit of 869 mm between September and March and excess of 837 mm from April to August. The irregularity of rainfall in the Coastal Tablelands promoted differential responses in the development and productivity of varieties of sugarcane. Varieties RB93509 and RB931003 are considered options for the varietal management in this region.