Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 120-127).

Thesis (M.A.)--Carleton University, 2001. / Includes bibliographical references (p. 185-195). Also available in electronic format on the Internet.

Thesis - University of Michigan. / Reprinted from the American naturalist, vol. LXXX, no. 794 ... September-October, 1946. Literature cited: p. 546.

Thesis (Ph.D.)--University of Delaware, 2010. / Principal faculty advisors: James J. Corbett and Jeremy M. Firestone, College of Earth, Ocean, & Environment. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 128-139).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 92-95). Also available via the Internet.

Field studies were conducted at Lincoln University of Missouri (USA) and Hokkaido University (Japan) to: (i) study the relationships between greenhouse gases emissions and soil properties, (ii) assess the influence of agricultural practices on greenhouse gas fluxes and soil properties and (iii) improve the quantification of greenhouse gases from soil in agricultural fields using geospatial technologies. Results showed that besides soil temperature (T), soil thermal properties such as thermal conductivity (K), resistivity (R) and diffusivity (D) and soil pore spaces indices such as the pore tortuosity factor and the relative gas diffusion coefficient (Ds/Do) are controlling factors for greenhouse gases emissions. Soil thermal properties correlated with greenhouse gases emissions when soil temperature could not. The study has found that predicted Ds/Do and correlate with greenhouse gas fluxes even when the air-filled porosity and the total porosity from which they are predicted did not. We have also showed that Ds/Do and can be predicted quickly from routine measurements of soil water and air and existing diffusivity models found in the literature. Agricultural practices do seriously impact greenhouse gases emissions as showed by the effect of mechanized tillage operations on soil physical properties and greenhouse gas fluxes in a corn and soybean fields. In fact, our results showed that tractor compaction increased soil resistance to penetration, water, bulk density and pore tortuosity while reducing air-filled porosity, total pore space and the soil gas diffusion coefficient. Changes in soil properties resulted in increased CO2, NO and N2O emissions. Finally, our results also confirmed that greenhouse gas fluxes vary tremendously in space and time. As estimates of greenhouse gas emissions are influenced by the data processing approach, differences between the different calculation approaches leads to uncertainty. Thus, techniques for developing better estimates are needed. We have showed that Geographic Information Systems (GIS), Global Positioning System (GPS), computer mapping and geo-statistics are technologies that can be used to better understand systems containing large amounts of spatial and temporal variability. Our GIS-based approach for quantifying CO2, CH4 and N2O fluxes from soil in agricultural fields showed that estimating (extrapolating) total greenhouse gas fluxes using the “standard” approach – multiplying the average flux value by the total field area – results in biased predictions of field total greenhouse gases emissions. In contrast, the GIS-based approach we developed produces an interpolated map portraying the spatial distribution of gas fluxes across the field from point measurements and later process the interpolated map produced to determine flux zones. Furthermore, processing, classification and modeling enables the computation of field total fluxes as the sum of fluxes in different zones, therefore taking into account the spatial variability of greenhouse gas fluxes.

Microcomputer software for capital cost analysis in greenhouse energy management is developed for use by extention workers in agriculture. A "template" for proprietary "spreadsheet" software is created that models greenhouse operation and performs a Net Present Value analysis of the cash flow for the life of up to ten energy saving techniques chosen by the grower. The results are displayed on the screen or printed out. Variables can be altered to suit specific user's needs and to check sensitivity of the model. A survey of local greenhouse growers was done to determine the specifications for the software developed and to verify the accuracy of the model. The resulting program is designed to run under MS-DOS on the IBM personal computer or any other similar microcomputer. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate

The greenhouse whitefly (Trialeurodes vaporariorum) is one of the most destructive pests of greenhouse tomato (Lycopersicon esculentum) crops. The success of biological or insecticidal control of whiteflies has never been complete. Attention has therefore been directed recently to the possibility of developing tomato cultivars resistant to whiteflies. Whiteflies were caged on leaflets of ten tomato cultivars, two of the woolly mutant lines and four other species of Lycopersicon to observe the effect of host plants within this genus on fecundity and longevity of the insects. The results showed wide variation among hosts. Significant negative correlations were revealed between the mean density of glandular hairs on the upper foliar surface of different cultivars and means for the fecundity of whiteflies caged on these cultivars. A high level of resistance to whitefly, not related to density of glandular hairs, was observed in plants that were either Van Wert's woolly mutant or L. peruvianum var. humifusum. Resistance of the former seemed to be related to a high density of branched non-glandular trichornes whereas that of the latter was not morphologically apparent. There were indications of both antibiosis and nonpreference operating in the humifusum. Further experimentation revealed a high nymphal mortality for whiteflies developing on plants of this line, reduced fecundity of adults which had developed on the humifusum, and a preponderance of male progeny from adult insects which had lived exclusively on these plants. It was concluded that the resistance of L, peruvianum var. humifusum to whitefly is sufficient to justify its use in a breeding program to develop greenhouse tomato cultivars resistant to this pest. / Land and Food Systems, Faculty of / Graduate

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