Thesis (Ph. D.)--Washington State University, December 2008. / Title from PDF title page (viewed on Apr. 29, 2010). "School of Economic Sciences." Includes bibliographical references.

Thesis (M.S.)--University of Kentucky, 2002. / Title from document title page. Document formatted into pages; contains viii, 51 p. : ill, maps. Includes abstract. Includes bibliographical references (p. 49-50).

No description available.

This dissertation investigates: (1) the climate change effects on the mean and higher order moments of crop yield distributions; (2) the effects of irrigation with and without its interactive terms with climate variables; (3) the climate effects on crop mix and climate change adaptation. The first essay explores how the climate change impacts the crop yield distribution. Using the flexible moment based approach, this study infers that external climate factors influence not only mean crop yield and variability, but also its higher order moments, skewness and kurtosis. The climate effects on each moment vary by crops. The second essay examines the irrigation effects on the mean crop yield. While the irrigation effects estimated from the model with irrigation dummy are constant regardless of climate conditions, the irrigation effects estimated from the model with irrigation dummy and interactive variables between irrigation and climate are affected by external climate factors. This study shows that as temperature increases, the irrigation effects are decreased and irrigation reduces damages from extreme temperature conditions. Precipitation and PDSI effects are also diminished under irrigation. The third essay explores the effects of climate on crop producers' choice. Our findings point out that the climate factors have significant impacts on crop choice and future climate change will alter the crop mix. Under the projected climate change of increasing temperature and precipitation, wheat and soybeans cropland will be switched to upland cotton. The major producing locations of upland cotton, rice, and soybeans will be shifted to the north. However, most of corn will be still cultivated in the Corn Belt and changes in acreage planted will not be significant.

Extensive land areas in arid and semi-arid regions contain excessive amounts of salt which inhibit or prevent the growth of desirable crop plants. This problem is increasing with the development of extensive irrigation projects. The future of irrigation agriculture will depend upon the development and the utilization of means of (1) preventing salt accumulation, (2) reclaiming salted soils. and (3) making the best use of those soils which by reason of drainage problems, soil texture and permeability, poor quality irrigation water, etc. are unsuited for economic reclamation. The utilization of land that is not feasible to completely reclaim, at least under present economic conditions, will depend upon the selection, development, and use of varieties and strains of crop plants which will produce economically under such conditions. The objectives of this research are to (1) test on a preliminary basis the salt tolerance of a number of promising crop plant materials. (2) observe the effect of salt upon plant behavior and growth, and (3) develop various methods of evaluating plant materials for salt tolerance.

Exploiting induced genetic diversity through using mutagenesis is particularly important in giant miscanthus (Miscanthus x giganteus; Mxg) due to its restricted genetic variability. Experiments were conducted to develop an efficient in vitro propagation protocol for Mxg, induce mutations in Mxg using a chemical mutagen, and select Mxg in vitro for heat tolerance. To optimize in vitro propagation of Mxg, five explant types [i.e. immature inflorescences, shoot apex (in vitro), shoot apex (greenhouse), leaf explants (in vitro), and leaf explants (greenhouse)] were tested on five media. Shoot forming calli from immature inflorescences, an excellent source of explant in Mxg, grown in media with 13.6 microM 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.44 microM 6-benzylaminopurine (BA) resulted in greatest shoot regeneration rate. Optimization of explant and callus type and media resulted in efficient in vitro proliferation of Mxg and the developed protocol was utilized in consecutive experiments of mutation induction and in vitro selection of Mxg for heat tolerance. Immature inflorescence explants (1-2 mm) were treated with 0.6%, 1.2%, and 1.8% of ethyl methanesulfonate (EMS) whereas the calli (1-2 mm3) were treated with 1.2%, 2.4%, and 3.6% of EMS for 90 min. Results of inter simple sequence repeat PCR analysis revealed polymorphisms indicating presence of genetic differences in Mxg putative mutants. In vitro callus cultures (mutagen treated and non-treated) of Mxg subjected to temperature treatments of 45±2°C for 12 hrs or 40±2°C for 7 days were selected for heat tolerance. Assessment results of electrolyte leakage and photosystem II (PS II) efficiency tests indicated a significant difference in percent membrane damage among Mxg clonal lines whereas PSII was weakly affected by the heat stress. The results suggest that in vitro derived Mxg clonal lines may be utilized for further studies of Mxg heat tolerance in developing potential Mxg ecotypes to adapt to different thermal environments. These studies provided the first investigation of in vitro induced mutagenesis in Mxg using a chemical mutagen. Genetic analysis results presented in this study indicates the potential use of developed Mxg putative mutants in future research programs, although significant morphological alterations were not observed during preliminary screening in the greenhouse.

Crop residues can make a significant contribution to the energy sector in Kenya. The purpose of this study was to identify the availability and spatial distribution of crop residues and their energy potential through the creation of a Geographical Information System (GIS) model. This information is important to the successful utilisation of these residues. In addition, a GIS tool was created that automates the resource estimation process for the purpose of identifying potential biomass energy plant sites. This study was conducted considering six provinces: Rift Valley, Western, Nyanza, Eastern, Central and Coast. The Rift Valley Province was selected as the case study for model tool creation and the crops considered in the study were maize, wheat, rice and sugarcane. The study was a quantitative one entailing the collection of secondary data in the form of crop production statistics and spatial data which comprised population, land use and road shape files and analysis using GIS. Residues to Product Ratios were used to estimate the amount of crop residues while Lower Heating Values assessed the energy potential. Moreover, ArcGIS Model Builder was used to create the GIS model tool for the feasibility of a potential biomass energy plant. The results of this study indicated the amount of crop residues that can be generated in Kenya to be about 7,384,600 tonnes with an energy potential of approximately 124,300 TJ/year. Rift Valley Province was found to have the highest residue generation of about 3,866,000 tonnes with a corresponding energy potential of about 64,800 TJ/year. The GIS model showed that the Rift Valley Province and Uasin Gishu, Trans Nzoia, and Nandi districts all had the potential for high residue generation resulting from their high agricultural production and high yields. The modelling tool was also able to demonstrate the increase in the amount of crop residues that can be collected using different radii around a potential biomass plant. The main conclusion was that crop residues have a high potential for energy generation in Kenya. In addition, a GIS model tool was created for Rift Valley Province which can be transferred to any other region, in order for the local energy planners to supply the model with their own parameters to obtain locally based results.

No description available.

No description available.

No description available.