984 resultados para Soil water potential


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Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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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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The objective of this study was to compare the gas exchange, photosynthetic capacity and water potential of sugarcane genotypes cultivated under water deficit conditions imposed during the initial growth phase. Experiments were performed in a greenhouse using two sugarcane genotypes namely: HoCP93-776 (drought susceptible) and TCP02-4587 (drought tolerant). Sixty days after planting, two different water treatments were applied (i.e., with or without water deficit). At 0,30 and 60 days after the treatment, gas exchange variables were evaluated for their relationship with water use, intrinsic instantaneous water use efficiency and instantaneous carboxylation efficiency. The SPAD index, photosynthetic pigments, water potential and relative water content in the leaves were also analyzed. The genotype HoCP93-776 was more sensitive to drought treatment as indicated by the significantly lower values of SPAD index, photosynthetic pigments, water potential (Ψw) and relative water content (RWC) variables. The genotype TCP02-4587 had higher water potential, stomatal control efficiency, water use efficiency (WUE), intrinsic instantaneous water use efficiency (WUEintr), instantaneous carboxylation efficiency and photosynthetic capacity. The highest air vapor pressure deficit during the drought conditions could be due to the stomatal closing in the HoCP93-776, which contributed to its lower photosynthetic capacity.

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The pineapple crop has a permanent demand for water, variable and dependent on their stage of development, which may affect the production and fruit quality. This study aimed to evaluate the chemical quality of fruits Smooth cayenne pineapple submitted to different levels and frequency of water replacement in the soil. We used a randomized block design in a 4 x 2 factorial arrangement, consisting of four levels of soil water replenishment (50%, 75%, 100% and 125% of crop evapotranspiration) and two irrigation frequencies (1 and 3 days) with four replications. We evaluated the parameters: juice yield (RS), hydrogen potential (pH), total soluble solids (SST), titratable acidity (ATT), SST/ATT relationship, ascorbic acid (AA). It was observed that the blades and irrigation frequencies did not affect the juice yield (RS) and ascorbic acid (AA), the increase of the blades irrigation influenced positively the quality of the fruit as it increases the values of total soluble solids (SST) decreases the acidity (ATT), raises the relationship SST/ATT and hydrogen potential (pH).

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

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Although highly weathered soils cover considerable areas in tropical regions, little is known about exploration by roots in deep soil layers. Intensively managed Eucalyptus plantations are simple forest ecosystems that can provide an insight into the belowground growth strategy of fast-growing tropical trees. Fast exploration of deep soil layers by eucalypt fine roots may contribute to achieving a gross primary production that is among the highest in the world for forests. Soil exploration by fine roots down to a depth of 10 m was studied throughout the complete cycle in Eucalyptus grandis plantations managed in short rotation. Intersects of fine roots, less than 1 mm in diameter, and medium-sized roots, 1-3 mm in diameter, were counted on trench walls in a chronosequence of 1-, 2-, 3.5-, and 6-year-old plantations on a sandy soil, as well as in an adjacent 6-year-old stand growing in a clayey soil. Two soil profiles were studied down to a depth of 10 m in each stand (down to 6 m at ages 1 and 2 years) and 4 soil profiles down to 1.5-3.0 m deep. The root intersects were counted on 224 m(2) of trench walls in 15 pits. Monitoring the soil water content showed that, after clear cutting, almost all the available water stored down to a depth of 7 m was taken up by tree roots within 1.1 year of planting. The soil space was explored intensively by fine roots down to a depth of 3 m from 1 year after planting, with an increase in anisotropy in the upper layers throughout the rotation. About 60% of fine root intersects were found at a depth of more than 1 m, irrespective of stand age. The root distribution was isotropic in deep soil layers and kriged maps showed fine root clumping. A considerable volume of soil was explored by fine roots in eucalypt plantations on deep tropical soils, which might prevent water and nutrient losses by deep drainage after canopy closure and contribute to maximizing resource uses.

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