Academic literature on the topic 'Relative water content'

Remotely sensing plant canopy water status remains a long term goal of remote sensing research. Established approaches to estimating canopy water status - the Crop Water Stress Index, the Water Deficit Index, the Equivalent Water Thickness and the many other indices - involve measurements in the thermal or reflective infrared. Here we report plant water status estimates based upon analysis of polarized visible imagery of a cotton canopy measured by Ground Multiangle SpectroPolarimetric Imager (GroundMSPI). Such estimators potentially provide access to the plant hydrological photochemistry that manifests scattering and absorption effects in the visible spectral region.

For this research, the abnormality of tissue cultured plantlets,vitrification, was examined in Gypsophila paniculata.Measurement of the relative water content and water saturation deficit of plantlets in culture revealed that vitrified plantlets contain relatively more water and less air spaces than non-vitrified plantlets.The effect of relative humidity on vitrification and growth was investigated using a variety of methods.From the results found, it was determined the defining characteristic of vitrified plantlets is water filled intercellular spaces. It was also determined that the primary cause of vitrification is high relative humidity resulting in a lack of transpiration in vitro but that other factors such as unbalanced mineral nutrition or high medium cytokinin can exacerbate vitrification.Further research in tissue culture may investigate the influence of relative humidity on plant growth and morphology, the mechanism by which plants exclude water from their intercellular spaces and refine in vitro tissue mineral analysis as a means by which critical mineral concentrations can be determined.<br>Doctor of Philosophy (PhD)

The development of a precise, non-destructive method to measure leaf water status is an important step towards testing our theories and models of leaf hydraulic function. Many of the responses of stomata to rapid changes in leaf water content (minutes to hours) are difficult to measure, in part due to destructive sampling methodologies necessary for establishing leaf water content. In this thesis, I use the technology of nuclear magnetic resonance (NMR) relaxometry to measure dynamic in vivo leaf relative water content (RWC). I show how stomata respond to rapid water deficit with a high level of temporal precision, by combining this measure of leaf water status with other non-destructive technologies such as leaf gas exchange. I apply the new simultaneous measure of leaf water status and transpiration to measure leaf hydraulic conductance dynamically and repeatedly in the same leaf over a range of water contents for the first time. Furthermore, I use the technique to show how the response of stomata to rapid water deficit is adapted to climate in the leaves in eucalypts, the dominant genus of tree in most Australian biomes. This research develops the new low-field NMR sensor as a useful tool for uncovering processes in leaf physiology and hydraulics, in conjunction with other non-destructive technologies and add to our understanding of the finely tuned relationship between climate and leaf physiology in eucalypts.

Liners are used in the engineered containment systems such as landfills for controlling the migration of contaminants. Although there are several techniques for detecting the leakages through the liners, use of the electrical resistivity method can assist in timely detection of contaminant migration in cost-effective manner. This method is based on the well-established fact that the electrical resistivity of soils and other geomaterials is much higher than the electrical resistivity of water, leachates or any liquid effluents which may permeate the landfill foundation material. Additionally, the geotechnical properties of a soil exhibit a close relationship with its electrical resistivity values for different conditions. This thesis presents the results of investigation into the interaction between the various electrical factors pertaining to resistivity tests in Perth sandy soil (specifically AC-input voltage and frequency) and those controlling the soil characteristics, specifically water/fluid content and relative density of the soil, and the types of permeant employed in the tests, namely distilled water, tap water, three leachates and seawater. For a landfill system situated near a salt water body, the effects of seawater and seawater-leachate intrusion have also been scrutinized. For the measurement of electrical resistivity for different soil density and contamination conditions, the experimental apparatus was developed as per Australian standard AS 1289.4.4.1-1997 as a significant part of the thesis work. The test results indicate that the resistivity of the sandy soil is almost independent of both AC-input voltage and frequency within the ranges used, while the choice of electrode material has an insignificant effect on the outcome of tests using this method. It is observed that the resistivity of sandy soil decreases rapidly with an increase in water/fluid content, but the rate of decrease reduces considerably for water contents over 12% in the case of distilled water and 10% for tap water, irrespective of the relative density. The resistivity is found to decrease almost linearly with an increase in relative density. However, the effect of relative density on the electrical resistivity of the soil is found to be negligible at higher water contents. In the landfills and similar containment systems, there is a possibility of leakage of leachate across the liners and/or seawater intrusion, depending on the location of the landfills. Hence, the study was conducted to evaluate the effects of contamination on the electrical resistivity of the Perth soil by changing the fluid content with various combinations of tap water, three different leachates and seawater. The study shows that for any mix of leachate and tap water, the resistivity decreases rapidly with increasing fluid content; however, the rate of decrease reduces significantly for fluid contents over 9%, irrespective of the type of leachate. Almost the same trend is observed for the case of seawater. Correlations between electrical resistivity, water content, relative density, amount and the composition of permeating fluid, which are applicable to the soil and permeating fluids used in the study, have also been developed and presented.

Memoria para optar al Título Profesional de Ingeniero Forestal<br>Peumus boldus Mol. (Boldo), es una especie endémica y característica del bosque esclerófilo. Su potencial económico está relacionado con la comercialización de sus hojas. El problema asociado a este mercado tiene relación con la sostenibilidad del recurso en el tiempo. Considerando su potencial económico, se evaluaron las respuestas morfo-fisiológicas en rebrotes nuevos y vástagos remanentes, según intensidad de corta, en la Comuna de Olmué, Región de Valparaíso. Se establecieron tres parcelas de 0,2 hectáreas cada una, donde se midieron: número de vástagos por cepa, DAP de los vástagos por cepa y área basal a nivel de cepa. De las tres parcelas, una corresponde a una parcela control y las dos parcelas restantes fueron cosechadas parcialmente. Se seleccionaron 12 cepas control y 12 cepas intervenidas. Las variables hídricas medidas fueron: potencial hídrico de la hoja (a pre-alba (ΨA) y al mediodía (ΨMD)) y contenido hídrico relativo de la hoja (a pre-alba (CHRA) y al mediodía (CHRMD). Para la caracterización del crecimiento de rebrotes se midieron el DAC y altura, y para la evaluación del crecimiento de los vástagos remanentes se midió el DAP de todos los vástagos por cepa. Para estimar la biomasa de rebrotes, se construyeron modelos de regresión utilizando el peso seco de 20 rebrotes y las variables predictoras DAC y altura. Para estimar la biomasa de los vástagos remanentes, se emplearon funciones de biomasa determinadas por Durán (2005). Por último, se analizó la acumulación de biomasa aérea total de boldo en cepas control y cepas intervenidas para un período de evaluación de un año. Los resultados muestran que el bosque con presencia de boldo presentó una densidad promedio de 207 cepas/ha correspondientes a un Gha inicial de 5,06 m2/ha. Las cepas presentaban en promedio nueve vástagos que, en su mayoría eran menores a 5 cm de DAP. Luego de la cosecha, Gha se redujo a 4,45 m2/ha. El potencial hídrico a pre-alba (ΨA), mostró diferencias significativas entre el tratamiento control y el tratamiento intervención (vástagos y rebrotes). A su vez el potencial hídrico a mediodía (ΨMD) siguió la misma tendencia presentada en ΨA. Al comparar el potencial hídrico dentro de los tratamientos, se observaron diferencias significativas en los tres casos estudiados. Con respecto al contenido hídrico relativo (CHR), se observaron diferencias significativas para el tratamiento control y el de intervención de vástagos tanto en pre-alba como en mediodía. Dentro del tratamiento sólo se observaron diferencias significativas en el tratamiento de intervención de vástagos, en donde en la medición del mediodía se presenta un CHR menor al observado a pre-alba. En el crecimiento de rebrotes el DAC y la altura presentaron un promedio de 4,8 mm y 34,1 cm respectivamente. El diámetro a la altura del cuello (DAC) tuvo una variación entre 1,1 mm y 15,1 mm, mientras que la altura presente en los rebrotes tomó valores entre los 0,40 cm y los 168 cm. En el crecimiento de vástagos remanentes las cepas control presentaron un incremento en DAP de 0,1 cm mientras que las cepas intervenidas presentaron un incremento de 1,1 cm. Para estimar la biomasa aérea de rebrotes, se estableció el DAC como la mejor variable predictora y se obtuvo una producción de biomasa aérea total de rebrotes de 1,03 kg y por componente (hojas y tallo) de 0,187 kg y 0,523 kg respectivamente a nivel de individuo. Para la biomasa aérea de vástagos remanentes, el componente más representativo fue el fuste, seguido por la biomasa foliar. El crecimiento inicial de boldo mostró una baja recuperación de la biomasa total en cepas con cosecha parcial al final del primer año de crecimiento, por lo que la sostenibilidad de la producción de hoja de boldo no se encontraría asegurada.<br>Peumus boldus Mol. (Boldo), is an endemic species characteristic of the sclerophyllous forest. Its economic potential is related to the commercialization of its leaves. However, the problem associated with this market has to do with the sustainability of the resource over time. Considering its economic potential, the morpho-physiological responses in new shoots and remaining stems were evaluated, according to the intensity of cutting, in the Olmué Commune, Valparaíso Region. Three plots of 0,2 hectares each were established, where they were measured: number of stems per strain, DBH of stems per strain and basal area at strain level. Of the three plots, one corresponds to a control plot and the remaining two plots were partially harvested. Were selected 12 strains control and 12 partial harvest. The water variables measured were: leaf water potential (pre-dawn (ΨA) and noon (ΨMD)) and relative leaf relative water content (pre-dawn (RWCA) and noon (RWCMD). For the characterization of the growth of sprouts, the DRC and height were measured, and for the evaluation of the growth of the remaining shoots the DBH of all the shoots per strain was measured. To estimate the biomass of sprouts, regression models were constructed using the dry weight of 20 sprouts and the predictor variables DRC and height. To estimate the biomass of the remaining shoots, the biomass functions determined by Durán (2005) were used. Once the total aerial and component biomass was determined, the accumulation of total aerial biomass of boldo in control strains and strains intervened for an evaluation period of one year. The results showed that the forest with presence of boldo had an average density of 207 strains/ha corresponding to an initial basal area per hectare of 5,06 m2/ha. The strains showed on average nine stems, which were mostly smaller than 5 cm of DBH. After harvest, basal area per hectare was reduced to 4,45 m2/ha. The pre-dawn water potential (ΨA) showed significant differences between the control treatment and the intervention treatment (stems and sprouts). In turn the water potential at noon (ΨMD) followed the same trend presented in ΨA. When comparing the water potential within the treatments, significant differences were observed in the three cases studied. Regarding the relative water content (RWC), significant differences were observed for the control treatment and for the intervention of stems in both pre-dawn and noon. Within the treatment only significant differences were observed in the intervention treatment of stems, where in the noon measurement a lower RWC is present compared to pre-dawn. In the growth of sprouts the DRC and height presented an average of 4,8 mm and 34,1 cm respectively. The diameter at root collar height (DRC) had a variation between 1,1 mm and 15,1 mm, while the height present in the sprouts took values between 0,40 cm and 168 cm. In the growth of remnant stems the control strains had an increase in DBH of 0,1 cm while the intervened strains showed an increase of 1,1 cm. To estimate the aerial biomass of sprouts, DRC was established as the best predictor variable and a total aerial biomass production of 1,03 kg and per component (leaf and stem) of 0,187 kg and 0,523 kg respectively at the individual level. For the aerial biomass of remnant stems, the most representative component was the stem, followed by the leaf biomass. The initial growth of boldo showed a low recovery of the total biomass in strains with partial harvest at the end of the first year of growth, reason why the sustainability of the production of boldo leaf would not be assured.

Avaliar o estado hídrico das plantas é essencial para o monitoramento das culturas agrícolas e florestais. A interação da radiação eletromagnética com as plantas é um processo estudado por sensoriamento remoto (SR). Através da técnica de SR é possível interpretar os fatores que influenciam na quantidade de energia absorvida, transmitida e refletida pela planta. Neste estudo, buscou-se estabelecer as relações existentes entre variações nos parâmetros da água com o comportamento espectral e gerar modelos matemáticos que sejam capazes de predizer o conteúdo relativo da água (CRA) e espessura equivalente da água (EEA) em 11 diferentes espécies de Eucalyptus, utilizando um sensor hiperespectral. Os dados foram obtidos por meio da pesagem e respectiva leitura espectral das folhas, sendo que estas passaram por uma metodologia de desidratação. Tal metodologia permitiu encontrar uma diferença de reflectância média de 26% entre o máximo e mínimo teor de água na folha, provando a influência do CRA no comportamento espectral, sendo a água um dos fatores de maior domínio na reflectância na região do infravermelho médio (1300nm - 2500nm). A partir das curvas espectrais foi possível avaliar que os comprimentos de onda próximo ao 1400 nm e 1900 nm foram os mais sensíveis ao conteúdo de água. A análise de componentes principais permitiu reforçar estes resultados, uma vez que as pontuações (scores) dos componentes que apresentaram correlações significativas com o CRA tiveram maiores pesos (loadings) nas regiões espectrais citadas anteriormente. A partir das respostas espectrais também foram realizados os cálculos dos índices espectrais já descritos em literatura, e estes submetidos a análise de regressão simples para predição do CRA e EEA. O índice espectral calculado com a combinação de bandas do infravermelho médio (1300nm e 1450nm) foi o que apresentou melhores resultados ao predizer os parâmetros da água, sendo que o SR1300,1450 teve um R2=0,72 para o CRA e R2=0,81 para o EEA. Os dados espectrais foram correlacionados com os parâmetros da água, e encontrou-se que para o CRA o comprimento de onda 1881 nm apresentou um coeficiente de correlação máximo negativo de r= -0,89, enquanto que o EEA apresentou um coeficiente de correlação máximo negativo de r= -0,79 no comprimento de onda 2165 nm. Foram testados três métodos de seleção das variáveis hiperespectrais para gerar um modelo matemático por meio de uma regressão linear. Para o parâmetro CRA, o método de seleção de variáveis stepwise foi o que gerou o maior (R2= 0,86) e um RMSE = 13,85%, sendo que neste método restaram apenas seis variáveis preditoras. Enquanto que o método de seleção de variáveis pelas regiões do espectro foi o mais preciso ao predizer o parâmetro EEA, com um R2= 0,87 e um RMSE = 0,00012 g/cm2, sendo necessárias apenas 5 variáveis espectrais.<br>The hydric condition assessment of plants is essential for monitoring agricultural and forest cultures. The interaction of electromagnetic radiation with plants is a process studied by remote sensing. Through this technique it is possible to interpret the factors that plays influence on the quantity of energy absorbed, transmitted and reflected by the plant. In this study was sought the establishment of existing relations between variations on the water parameters and the spectral behavior and then to generate mathematical models capable of predictiong the relative water content (RWC) and equivalent water thickness (EWT) among 11 different Eucalyptus species using a hyperespectral sensor. The data was obtained through weighting followed by reflectance readings of leaves in which the leaves had gone through a dehydrating methodology. The dehydrating methodology allowed finding a average reflectance difference of 26% between the maximum and the minimum water content on the leaf, proving the influence of the RWC in the spectral behavior in which the water plays great influence in the medium infrared reflectance region (1300 nm - 2500 nm). From the spectral curves it was possible to conclude that the wavelengths near 1400 nm and 1900 nm were the most sensitive to the water content. The principal content analyses reinforced these results once the scores of the components that showed significant relations with the RWC had the bigger loadings in the mentioned spectral regions. Spectral indices already described in literature were calculated using the spectral responses and their results were submitted to a simple regression for predicting RWC and EWT. The spectral index calculated by the combination of medium infrared (1300 nm and 1450 nm) was the one which had better results when prediction water parameters in which SR... had an R2=0,72 for RWC and R2=0,81 for EWT The spectral data was correlated to the water parameters and it was observed that for the RWC at 1881 nm showed a maximum negative coefficient of correlation of r=-0,89 whereas the EWT showed a maximum negative coefficient of correlation of r=-0,79 at 2165 nm. Three selection methods were tested for the hyperespectral variables in order to generate a mathematical model through linear regression. For the RWC parameter, the selection method of stepwise variables was the one which generated and R2=0,86 and a RSMSE = 13,85%. For this method just 6 predicting variables were left. While the variables selection method by spectral regions was the most precise when predicting the EWTparameter with a R2 = 0,87 and a RMSE = 0,00012 g/cm2 being just 5 spectral variables necessary.

Resumo: A cana-de-açúcar (Saccharum spp.) é uma das principais culturas das regiões tropicais, cuja produtividade agrícola pode ser afetada pelo déficit hídrico. Para investigar o processo de tolerância e sensibilidade ao déficit hídrico, diferentes parâmetros fisiológicos foram avaliados em cultivares de cana-de-açúcar tolerantes (SP83-2847 e CTC15) e sensível (SP86-155) ao déficit hídrico. A deficiência hídrica afetou todo o aparato fotossintético das plantas de forma diferenciada dentro e entre as cultivares. A taxa fotossintética e condutância estomática diminuíram significativamente para todas as cultivares submetidas ao estresse. Nas plantas controle das cultivares (cv) tolerantes SP83-2847 e CTC15 observou-se que a taxa fotossintética apresentou valores mais altos em comparação a cultivar sensível SP86-155. Resultados do teor relativo de água mostraram que a cultivar CTC15 apresentou melhor condição hídrica durante o período de déficit hídrico. A eficiência quântica do fotossistema II da cultivar SP83-2847 mostrou maior estabilidade nos últimos dias do tratamento experimental, sugerindo que o decréscimo do teor relativo de água estimulou o ajuste da capacidade fotossintética frente às alterações da disponibilidade hídrica. De modo geral, as cultivares SP83-2847 e CTC15, consideradas tolerantes, sob déficit hídrico exibiram melhor desempenho em relação a cultivar sensível SP86-155. Os dados permitem sugerir que tais parâmetros fisiológicos podem ser empregados na avaliação e distinção de genótipos de cana-de-açúcar tolerantes e sensíveis ao déficit hídrico.<br>Abstract: The sugarcane (Saccharum spp.) is one of the main crops cultivated in tropical areas, whose agricultural productivity can be affected by drought. To investigate the tolerance and sensitivity process to water deficit, various physiological parameters were evaluated in sugarcane cultivars considered tolerant (SP83-2847 and CTC15) and sensitive (SP86-155) to drought. The water deficit affected the entire photosynthetic apparatus of all plants in different manners, inside and among cultivars. The photosynthetic rate and stomatal conductance decreased significantly for all cultivars, submitted to water stress. In control plants of the tolerant cultivars SP83-2847 and CTC15, it was observed that the photosynthetic rate showed better values in comparison to sensitive cultivar SP86-155. According to relative water content results of the cultivar CTC15 showed better condition water performance during the drought. The quantum efficiency photosystem II of the cultivar SP83-2847 showed greater stability in recent days of the experimental treatment, suggesting that the decline in the relative water content stimulated the adjustment of photosynthetic capacity to face the changes in water availability. Thus, cultivars SP83-2847 and CTC15, considered tolerant under water deficit, showed better performance in comparison to sensitive cultivar SP86-155. The data suggest that these physiological parameters can be used in the evaluation and distinction of drought tolerant and sensitive sugarcane genotypes.<br>Orientador: Sonia Marli Zingaretti<br>Coorientador: Clara Beatriz Hoffmann-Campo<br>Banca: Rinaldo Cesar de Paula<br>Banca: José Renato Bouças Farias<br>Mestre

A prominent landslide deposit in the Slope Basin seaward of the Megasplay Fault in the Nankai Trough was emplaced by a high-mobility landslide based on analysis of physical properties and seismic geomorphology. Slide acceleration is a critical variable that determines amplitude of slide-generated tsunami but is many times a variable with large uncertainty. In recent controlled laboratory experiments, the ratio of the shear stress to yield strength (defined as the Flow Factor) controls a wide spectrum of mass movement styles from slow, retrogressive failure to rapid, liquefied flows. Here, we apply this laboratory Flow Factor approach to a natural landslide in the Nankai Trough by constraining pre-failure particle size analysis and porosity. Several mass transport deposits (MTDs), were drilled and cored at Site C0021 in the Nankai Trough during International Ocean Discovery Program (IODP) Expedition 338. The largest, MTD B, occurs at 133-176 meters below seafloor and occurred approximately 0.87 Mya. Slide volume is 2 km3, transport distance is 5 km, and average deposit thickness is 50 m (maximum 180 m). Pre-failure water content was estimated from shallow sediments at Site C0018 (82%). The average grain size distribution is 37% clay-sized, 60% silt-sized, and 3% sand-size particles as determined by hydrometer analyses of the MTD. Together, the water content and clay fraction predict a Flow Factor of 3.5, which predicts a relatively high mobility slide. We interpret that the landslide that created MTD B was a single event that transported the slide mass relatively rapidly as opposed to a slow, episodic landslide event. This is supported by the observation of a completely evacuated source area with no remnant blocks or retrogressive headscarp and an internally chaotic seismic facies with large entrained blocks. This approach can be extended to other field settings characterized by fine-grained siliciclastics and where water content and clay percentages are known.