150 resultados para Water retention


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For orchid cultivation in containers is essential to select the right substrate, since this will influence the quality of the final product, it serve as a support for the root system of the plants. This study aimed to evaluate different agricultural residues and expanded clay in Oncidium baueri Lindl. orchid cultivation. The plants were subjected to treatments: pinus husk + carbonized rice husk, pinus husk + coffee husk, pinus husk + fibered coconut, pecan nut husk, expanded clay, fibered coconut, coffee husk, carbonized rice husk, pinus husk. After eleven months of the experiment, the following variables were evaluated: plant height; largest pseudo-bulb diameter; number of buds; shoot fresh dry matter; the longest root length; number of roots; root fresh matter; root dry matter; and electric conductivity; pH and water retention capacity of the substrates. Except the expanded clay, the other substrates showed satisfactory results in one or more traits. Standing out among these substrates pinus husk + coffee husk and pine bark + fibered coconut, which favored the most vegetative and root characteristic of the orchid. The mixture of pinus husk + coffee husk and pinus husk + fibered coconut, provided the best results in vegetative and root growth of the orchid Oncidium baueri and the expanded clay did not show favorable results in the cultivation of this species.

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

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This work shows the preparation and characterization of the new nanocomposites based on fibroin and biocellulose. Bacterial cellulose (BC) is an exopolysaccharide produced by bacteria of the genus Gluconacetobacter, which it has identical chemical structure of the cellulose from plants and it has gained attention in the field of research for its unique properties as excellent mechanical properties when dry and hydrated , higher capacity of water retention, moldability , biodegradability and excellent biological affinity . Silk fibroin (SF) is a structural protein present in the cocoon of the silkworm, Bombyx mori, has been identified as suitable for developing optical devices, tissue engineering application, enzyme immobilization, controlled release drug agent biopolymer. Silk fibroin/bacterial cellulose nanocomposite films were prepared impregnating different cellulose charges (0.5 %, 1.0 %, 1.5 %, 2.5 %, 5.0 % and 10.0 %) weight/weight. According mechanical tests and water and Paynes's cup permeability showed that SF/BC 1% nanocomposite has the most relevant results. Poliethylenoglicol (PEG) containing SF films improved optical and mechanical properties when compared to pristine SF film. New SF/BC nanocomposites could be applied in Medicine, as biodegradable packaging and flexible substrates for OLEDs.

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

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This manuscript aims proposing a methodology for correlating soil porosity to the respective geological units using geostatistical analysis techniques, including interpolation data by kriging. The site studied was in Lorena municipality, Paraíba do Sul Valley, southeastern Brazil. Specifically all studies were carried out within an area of 12 km2 located at Santa Edwirges farm. The database comprehended 41 soil samples taken at different geological and geomorphologic units at three different depths: surface, 50 cm and 100 cm depth. The geostatistical analyses results were correlated to a geological mapping specifically elaborated for the site. This mapping accounts for two different geological formations and a geological contact characterized by a shearing zone. The results indicate the existence of a significant relationship between the soil porosity and the respective geological units. The studies revealed that the residual soils from weathered granitic rocks tend to have higher porosities than the residual soils from weathered biotite gneiss rocks, while the soil porosity within the shearing zone is relatively un-sensitive to the respective geological formation. The spatial patterns observed were efficient to evaluate the relationship between the soil porosity, geology unit and the and geomorphology showing a good potential for correlating with others soil properties such as hydraulic conductivity, soil water retention curves and erosion potentials.

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

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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

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Some ecological attributes of planktonic copepods (composition, diversity, abundance and its relations with limnological variables) were compared in two deep and dendritic reservoirs, 470km from each other, with contrasting water retention time (WRT) and ages of construction. Data were grouped from two different studies: samples were collected monthly between March/00 to February/01, on the Salto Caxias Reservoir (Iguaçu River), and tri-monthly between January/00 to October/01, on the Chavantes Reservoir (Paranapanema River). Eight species of Calanoida and six of Cyclopoida were identified in both reservoirs. The highest richness was observed in Salto Caxias (12 taxa) when compared with Chavantes (8 taxa), and six species were exclusive to Salto Caxias and two from Chavantes. Salto Caxias was studied one year after the construction, consequently with higher nutrients values in this period and showed generally high mean values of Copepoda (nauplius, copepodits and adults) than Chavantes, which is 38 years old. Some parameters as transparency, conductivity, turbidity and total nitrogen were significantly related with copepod abundance. New formation and sufficient long WRT could be an important cause for the highest richness of Calanoida and total abundance of individuals in Salto Caxias Reservoir.

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This study was undertaken in a 1566 ha drainage basin situated in an area with cuesta relief in the state of São Paulo, Brazil. The objectives were: 1) to map the maximum potential soil water retention capacity, and 2) to simulate the depth of surface runoff in each geographical position of the area based on a typical rainfall event. The database required for the development of this research was generated in the environment of the geographical information system ArcInfo v.10.1. Undeformed soil samples were collected at 69 points. The ordinary kriging method was used in the interpolation of the values of soil density and maximum potential soil water retention capacity. The spherical model allowed for better adjustment of the semivariograms corresponding to the two soil attributes for the depth of 0 to 20 cm, while the Gaussian model enabled a better fit of the spatial behavior of the two variables for the depth of 20 to 40 cm. The simulation of the spatial distribution revealed a gradual increase in the depth of surface runoff for the rainfall event taken as example (25 mm) from the reverse to the peripheral depression of the cuesta (from west to east). There is a positive aspect observed in the gradient, since the sites of highest declivity, especially those at the front of the cuesta, are closer to the western boundary of the watershed where the lowest depths of runoff occur. This behavior, in conjunction with certain values of erodibility and depending on the land use and cover, can help mitigate the soil erosion processes in these areas.

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The aim of the work was to evaluate the productivity, leaf nutrient content and soil nutrient concentration in maize (Zea mays L.) grown in sequence with black oats (Avena strigosa Schreb.) under Leucaena diversifolia alley cropping agroforestry system (AFS) and traditional management system/sole crop (without trees-TS), after two years of cultivation following a randomized block design. The experiment was carried out in the Brazilian Association of Biodynamic Agriculture, in Botucatu—S?o Paulo, Brazil. Treatments were: control (C), chemical fertilizer application (F), biomass of L. diversifolia alley cropping application (B), biomass of L. diversifolia alley cropping + chemical fertilizer application (B + F). In the second year of management it was observed that black oat yield was higher in treatments B + F and F with significant difference in relation to the others treatments in both systems, followed by treatment B. Between systems, only treatment B showed significant difference, with higher yield value corresponding to AFS, reflecting the efficiency of AFS to promote soil fertility. Maize production presented the second year of cultivation an increasing trend in all treatments in both production systems. This result may be due to the cumulative effect of mineralization and maize straw and oats, along the experiment. How productivity was higher in the AFS system, could also be occurring effect of biological nitrogen fixation, water retention and reduction of extreme microclimate through the rows of L. diversifolia. Comparing the AFS and TS, it was observed that the concentration of N in leaf tissue was higher in the AFS treatments, probably due to nitrogen fixation performed through the rows of L. diversifolia, that is a nitrogen fixing tree species. After two years, carbon stocked in soil show higher values in the treatments biomass + fertilizer and biomass application, in both systems, AFS and TS.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The effect of ultrasound and osmotic dehydration pretreatments on papaya drying kinetics was investigated. The ultrasound pretreatment was carried out in an ultrasonic bath at 30 A degrees C. The osmotic pretreatment in sucrose solution was carried out in an incubator at 34 A degrees C and agitation of 80 rpm for 210 min. The drying process was conducted in a fixed bed dryer at 70 A degrees C. Experimental data were fitted successfully using the Page model for dried fresh and pretreated fruits, with coefficient of determination greater than 0.9992 and average relative error lower that 14.4 %. The diffusional model was used to describe the moisture transfer, and the effective water diffusivity was identified in the order of 10(-9) m(2) s(-1). It was found that drying rates of osmosed fruits were the lowest due to the presence of infused solutes, while the ultrasound pretreatment contributed to faster drying rates. Evaluation of the dried fruit was performed by means of total carotenoids retention. Ultrasound treatments in distilled water prior to air-drying gave rise to dried papayas with retention of carotenoids in the range 30.4-39.8 % and the ultrasonic-assisted osmotic dehydration of papayas showed carotenoids retention values up to 64.9 %, whereas the dried fruit without pretreatment showed carotenoids retention lower than 24 %.

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