Search results for "Transpiration"
showing 10 items of 240 documents
An integrated approach for high spatial resolution mapping of water and carbon fluxes using multi-sensor satellite data
2012
In the last years, modeling of surface processes - such as water, energy and carbon budgets, as well as vegetation growth- seems to be focused on integrated approaches that combine aspects of hydrology, biology and meteorology into unified analyses. In this context, remotely sensed data often have a core role due to the cross-cutting impact of this novel source of spatially distributed information on all these research areas. However, several applications - such as drought monitoring, yield forecasting and crop management - require spatially detailed products at sub-field scales, which can be obtained only with support of adequately fine resolution remote sensing data (< 100 m). In particul…
Evaluation of the B‐method for determining actual evapotranspiration in a boreal forest from MODIS data
2007
Boreal forests occupy about 11% of the terrestrial surface and represent an important contribution to global energy balance. The ground measurement of daily evapotranspiration (LEd) is very difficult due to the limitations on experiments. The objective of this paper is to present and explore the applicability of the B-method for monitoring actual LEd in these ecosystems. The method shown in this paper allows us to determine the surface fluxes over boreal forests on a daily basis from instantaneous information registered in a conventional meteorological tower, as well as the canopy temperature (T c) retrieved by satellite. Images collected by the MODIS (moderate resolution imaging spectrorad…
Effect of water stress on dry matter accumulation and partitioning in pot-grown olive trees (cv Leccino and Racioppella)
2013
Abstract Three different water regimes were applied on young pot-grown olive trees of the cultivars Leccino and Racioppella, amounting to 100% (treatment T100), 50% (treatment T50) and 25% (treatment T25) of water transpiration as determined by pot weight. During the two-year trial the following parameters were measured: midday stem water potential, shoots growth, total leaf area per tree, dry matter accumulation and partitioning in different parts of the plant (root, wood, leaves and fruits). Dry matter was affected by the water regime and cultivar. The cv Leccino, for T100, displayed a greater accumulation of total dry matter and fruit dry matter, while these two parameters were greatly r…
Comparison of Canopy Emissivity Parametric Models With TES Emissivity Measurements
2018
Canopy temperature is a key factor in many studies, such as evapotranspiration and heat fluxes estimation. To retrieve it accurately, it is needed a precise characterization of the emissivity in the thermal infrared spectral range. Several parametric models are proposed to retrieved effective emissivity at different observation angles, from the previous knowledge of the vegetation and soil emissivities. The present work compares some of these models with emissivity measurements obtained with Temperature-Emissivity Separation (TES) method. For that, FR97, Mod3 and Rmod3 parametric models have been compared with radiometric measurements. Emissivity measurements were done for 7 different obser…
Response of vine leaf water potential to quick variation in canopy exposure. Example of canopy opening manipulation of Merlot (<em>Vitis vinife…
2004
<p style="text-align: justify;">Plants are in general subject to rapid fluctuations in the environment, particularly as regards the interception of light and therefore water regime. It is important to know the duration and the amplitude of response of the water regime (first leaf water potential) when light interception changes suddenly under natural conditions. widely planted grape variety in the world) was chosen mainly because it offers convenient possibilities of canopy manipulation, ranging from an open and exposed type architecture, to a closed and shaded configurations simply by moving inside or outside a «foldable Lyre» type trellis. Leaf water potential was measured throughou…
Determination of Evapotranspiration and Annual Biomass Productivity of a Cactus Pear [Opuntia ficus-indica L. (Mill.)] Orchard in a Semiarid Environm…
2013
A micrometeorological approach based on the surface energy balance was adopted to estimate evapotranspiration fluxes and crop coefficient data from an irrigated cactus pear [Opuntia ficus-indica L. (Mill.)] orchard under Mediterranean climatic conditions. Highfrequency temperature readings were taken above the canopy top to get sensible heat flux values (HSR) using the surface renewal technique. These values were compared against eddy covariance sensible heat fluxes (HEC) for calibration. Latent heat flux (or evapotranspiration, ET) was obtained by solving the daily energy balance equation. Measurements of soil hydraulic components were integrated with the analysis of the surface energy flu…
Effects of irrigation on fruit ripening behavior and metabolic changes in olive
2012
Olive (Olea europaea, cv Leccino) fruits grown under different water regimes were analyzed by metabolomics and specific transcript accumulation analyses. The fruit from non-irrigated (rain-fed) and irrigated trees cultivated under field conditions, with a seasonal water amount equivalent to the calculated crop evapotranspiration (ETc) was compared in the last developmental phase and, in particular, at commercial harvest. Metabolomics (GC-MS) analysis identified several hundred metabolites in ripe mesocarp, 46 of which showed significantly different contents in the rain-fed and irrigated samples. Some compounds involved in primary metabolism (carbohydrates, amino acids, organic acids) and se…
Effects of ozone on photosynthetic CO2 exchange, chlorophyll a fluorescence and antioxidant systems in lettuce leaves
2002
The effects of ozone exposure on lettuce leaves were investigated by means of gas exchange, modulated chlorophyll a fluorescence and antioxidants systems. High ozone concentration decreased the rate of photosynthesis at light saturation level and changes in stomatal conductance and transpiration rate. However, an increase in intercellular CO 2 concentration indicated a decrease in the carboxylation efficiency. These data agreed with a reduction of non-cyclic electron flow and lower capacity to reduce the quinone pool. Ozone affected the ascorbate pool and decreased ascorbate peroxidase activity, increased lipid peroxidation, altered membrane properties and reduced the development of non-pho…
Response to long-term NaHCO3-derived alkalinity in model Lotus japonicus Ecotypes Gifu B-129 and Miyakojima MG-20: transcriptomic profiling and physi…
2014
The current knowledge regarding transcriptomic changes induced by alkalinity on plants is scarce and limited to studieswhere plants were subjected to the alkaline salt for periods not longer than 48 h, so there is no information availableregarding the regulation of genes involved in the generation of a new homeostatic cellular condition after long-termalkaline stress.Lotus japonicusis a model legume broadly used to study many important physiological processes includingbiotic interactions and biotic and abiotic stresses. In the present study, we characterized phenotipically the response toalkaline stress of the most widely usedL. japonicusecotypes, Gifu B-129 and MG-20, and analyzed global t…
Improvement of Temperature Based ANN Models for ETo Prediction in Coastal Locations by Means of Preliminary Models and Exogenous Data
2008
This paper reports the application of artificial neural networks for estimating reference evapotranspiration (ETo) as a function of local maximum and minimum air temperatures and exogenous relative humidity and evapotranspiration in twelve coastal locations of the autonomous Valencia region, Spain. The Penman-Monteith model for ETo prediction, as been proposed by the Food and Agriculture Organization of the United Nations (FAO) as the standard method for ETo forecast, has been used to provide the ANN targets. The number of stations where reliable climatic data are available for the application of the Penman-Monteith equation is limited. Thus, the development of more precise predicting tools…