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This study was conducted to improve knowledge of the impact of chronic soil water deficit and to test a novel technique of water management consisting of Lipo-chitooligosaccharides (LCO) spray application. It also aimed at evaluating changes in canopy reflectance due to water stress and LCO spray. Water stress during reproductive development resulted in an important decrease of plant physiological activity, vegetative growth, and productivity, and accelerated plant senescence at both water stress levels. Water deficit increased leaf reflectance in the visible and decreased it in the infrared ranges of the spectrum at both imposed stress levels. Foliar application of LCO affected overall plant physiological activity, increased flower and pod numbers. LCO treatment had the largest positive effect on the growth pattern of soybean at the medium stress level, which is the stress level most commonly observed in standard farm-field conditions. LCO treatment constitutes a potential technology for reducing water deficit effects. (Abstract shortened by UMI.)

Epicuticular waxes form a layer on the outer surface of all land plants and play a fundamental role in their interaction with the environment. Development of a rapid and accurate method for the characterization of these waxes could allow the use of wax composition as a novel phenotype during plant breeding and selection. In this study, the suitability of Direct Analysis in Real Time Mass Spectrometry (DART-MS) for the characterization of epicuticular waxes was investigated. This method provides a “fingerprint” of the relative abundance of all constituents in the analyte based on mass, is suitable for very high throughput, requires minimal sample preparation, and is able to provide for the characterization of even complex biological mixtures. Herein, the suitability of DART-MS for analysis of epicuticular wax was investigated through analysis of samples of extracted wax collected from the flag leaves of a 279 line association mapping population grown across four environments with two replicates in both irrigated and drought treatments. Additionally, for a subset of samples, wax was collected from glumes in order to test for differences in wax composition between tissue types. In all, a total of 3,454 wax extracts were analyzed with three technical replicates. The above analysis generated a total of 13,164 mass spectra (“fingerprints”), made at an average rate of 30 seconds each. Multivariate analyses including random forest, principal component analysis, and linear discriminant analysis, were used to identify the presence of differences between the spectra of wax from different tissues (leaves/glumes) and treatment types (irrigated/drought). The peaks best serving as predictors of sample class for each comparison were examined, and tentative identifications were made through comparison of the associated mass with literature and publicly available databases. As a separate test of concept, the ability to distinguish between the epicuticular wax compositions of individual varieties was determined through analysis of a group of closely related lines developed at CIMMYT which differed in agronomic performance.

Water resources in Canada are of major environmental, social and economic value. It is expected that climate change will be accompanied by more intense competition for water supply in water-stressed agricultural areas such as the southern Prairies. Beyond physical impacts, drought can be seen as a socio-economic and political problem which ultimately has implications for community-level vulnerability to climate change. This thesis presents empirical vulnerability case studies focused on the exposure-sensitivity and adaptive capacity of Coronach and Gravelbourg in southern Saskatchewan. The results illustrate the fact that farmers or ranchers are not merely passive victims of drought. They also take an active role in shaping the environment around them, thus affecting their own vulnerability to drought. Therefore, by understanding the causal linkages of the coupled social-environment system, a more comprehensive understanding of community vulnerability is achievable and informed decisions can be made based on this thorough understanding of local conditions. In the second part of this thesis, the potential of soft water path is evaluated as a possible adaptation strategy. Based on the results gathered in the first part of this thesis, adaptation measures are tailored to address specific needs of different sectors in the Town of Coronach and the Town of Gravelbourg while ensuring ecological sustainability. Examples of possible paths (adaptation measures) are suggested in order to increase community adaptive capacity to water shortages in light of future climate changes.

xvi, 227 leaves : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Physiology, 1971

The transfer of prey resources between ecosystems can have dramatic consequences for both recipient and donor systems by altering food web stability and the likelihood of trophic effects cascading across the ecosystem boundary. Landscape-scale factors influence the importance, direction and magnitude of energy flows, but may also alter the ability of consumer organisms to respond to spatio-temporal changes in allochthonous prey availability. Here, I used flood and drying disturbance gradients to investigate interactions between these two processes on populations of a riparian fishing spider Dolomedes aquaticus (Pisauridae). The abundance of aquatic insects with a winged adult stage, a major component of the diet of D. aquaticus, was markedly higher at less flood-prone rivers and declined with increasing flood disturbance. It was expected that spider populations would be largest at these stable rivers where the aquatic prey abundance was highest. However, a habitat (loose, unembedded riverbank rocks) manipulation revealed that the lack of scouring floods at these sites led to habitat-limited populations, preventing response to the increased prey resource. In fact a peak shaped relationship of spider biomass and abundance was found, with the largest spider populations at intermediately disturbed rivers. In addition, patchy habitat availability was the most likely cause of the small scale (4 m2) aggregation of spiders seen at the most stable and disturbed rivers. These patterns were also associated with strong interactions between the spiders. Stable isotope analysis of field collected spiders and an experimental manipulation of spider densities and food availability indicated that cannibalism rates were likely to be significantly higher at stable and disturbed rivers than those intermediate on the disturbance gradient. Differences in D. aquaticus population size structure and life history traits across the flood disturbance gradient were driven by interactions between resource availability, environmental stability and cannibalism rates. To separate the effects of habitat availability and aquatic prey abundance I used drying rivers, as the amount of aquatic insect prey alters as the water recedes. Desiccation mortality and low aquatic prey biomass most likely caused the spiders' spatial distribution and size class structure to alter in drying river reaches, potentially also leading to differences in cannibalism rates. Overall, cross-ecosystem transfers of prey had large impacts on the distribution, cannibalism rates and life history traits of D. aquaticus but their effects were modified by the nature of the ecosystem boundary. Thus river flow regime controlled the magnitude of the subsidy and its use by a consumer. Hence, cross-ecosystem subsidies will not always lead to larger consumer populations and consumer responses will depend on interactions between large-scale processes.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Thesis (M.Sc. Earth Sciences)--University of Waikato, 2008. / Title from PDF cover (viewed February 23, 2009) Includes bibliographical references (p. 72-75)

Climate change is promoting alterations in climatic conditions. This article analyzes the way how people deal with dry seasons in the community of Tucaque. Droughts are a rough limit in the development of any population. Even more if there are obstacles that retain the adaptive capacity to this event. These barriers are the economic resources scarcity and, the social and institutional factors. The latter two are seen in Tucaque where individualism dominates the people’s social life; there is also weak governance, and the weak connections with the Frias Municipality do not allow the right management of dry seasons. Droughts will continue happening so it’s a good idea to know the opportunities that may be used in order to take advantage of them and overcome the climatic stress.  So, there is the canal El Bronce, that reduces the drought effects; the Ronda Campesina de Tucaque, despite of the difficulties it is a respected and organized institution in the community;   ethno climatic knowledge that can be revalorize in front of the absence of meteorological stations; and the pitaya farming, which does not consume much water for its growth and it is a product with big economic possibilities. Being the agriculture a very sensitive activity to climatic modifications, actions taken against droughts will perfectly fit in adaptation measures to climate change. / El cambio climático está promoviendo modificaciones en las condiciones climatológicas. Este artículo ha optado por analizar la forma de lidiar contra las épocas secas en el caserío Tucaque. La sequía representa un grave limitante para el desarrollo de cualquier población, además de los obstáculos que disminuyen la capacidad adaptativa para este evento. Estas barreras implican la escasez de recursos económicos y; factores sociales e institucionales. Estas últimas se reflejan en el caserío Tucaque en donde el individualismo reinante en el centro poblado, la débil gobernanza del lugar y la relación superficial con la Municipalidad Distrital de Frías no permiten un adecuado manejo de los años secos. Las sequías van a continuar ocurriendo. En tal sentido es necesario también conocer las oportunidades que ellas nos presentan para poder aprovecharlas y así superar el estrés climático. Es así que se tiene al Canal El Bronce, el cual está aminorando los efectos de la sequía; a la Ronda campesina de Tucaque, la cuál a pesar de las dificultades es una institución respetada y organizada en el caserío; a los conocimientos etnoclimáticos  que pueden volver a ser revalorados frente a la carencia de estaciones meteorológicas; y al cultivo de la pitaya, la cual no requiere de mucha agua para su desarrollo y es un producto con grandes posibilidades económicas. Siendo la agricultura una actividad muy sensible a los cambios en el clima, las acciones que se tomen contra la sequía, van a encajar perfectamente en las medidas de adaptación al cambio climático.

Panama has a warm, wet, tropical climate. Unlike countries that are farther from the equator, Panama does not experience seasons marked by changes in temperature. Instead, Panama's seasons are divided into Wet and Dry. The Dry Season generally begins around mid-December, but this may vary by as much 3 to 4 weeks. Around this time, strong northeasterly winds known as "trade winds" begin to blow and little or no rain may fall for many weeks in a row. Daytime air temperatures increase slightly to around 30-31 Celsius (86-88 Fahrenheit), but nighttime temperatures remain around 22-23 Celsius (72-73 Fahrenheit). Relative humidity drops throughout the season, reaching average values as low as 70 percent. The Wet Season usually begins around May 1, but again this may vary by 1 or 2 weeks. May is often one of the wettest months, especially in the Panama Canal area, so the transition from the very dry conditions at the end of the Dry Season to the beginning of Wet Season can be very dramatic. With the arrival of the rain, temperatures cool down a little during the day and the trade winds disappear. Relative humidity rises quickly and may hover around 90 to 100% throughout the Wet Season. Drought forecasts can be an effective tool for mitigating some of the more adverse consequences of drought. The presented thesis compares forecast of drought indices based on seven different models of artificial neural networks model. The analyzed drought indices are SPI and SPEI-ANN Drought forecast, and was derived for the period of 1985-2014 on Panama Canal basin; I've selected seven of sixty-one Hydro-meteorological networks, existing in the Panama Canal basin. The rainfall is 1784 mm per year. The meteorological data were obtained from the PANAMA CANAL AUTHORITY, Section of Water Resources, and Panama Canal Authority, Panama. The performance of all the models was compared using ME, MAE, RMSE, NS, and PI. The results of drought indices forecast, explained by the values of seven model performance indices, show, that in Panama Canal has problem with the drought. Even though The Panama is generally seen as a wet country, droughts can cause severe problems. Significant drought conditions are observed in the index based on precipitation and potential evaporation found in this thesis; The Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), were used to quantify drought in the Panama Canal basin, Panama Canal, at multiple time scales within the period 1985-2014. The results indicate that drought indices based on different variables show the same major drought events. Drought indices based on precipitation and potential evaporation are more variable in time while drought indices based on discharge. Spatial distribution of meteorological drought is uniform over Panama Canal.