Call number: LD2668 .T4 1953 R3 / Master of Science

published_or_final_version / Botany / Doctoral / Doctor of Philosophy

No description available.

Call number: LD2668 .T4 1950 P5 / Master of Science

The sweet potato has become a major international crop and it is also the main staple food for many people in the developing world. This crop is desirable as it is high yielding, easy to grow and has a low cost of production. However, the tubers have a low protein content and a low concentration of amino acids, particularly the aspartate amino acid. This has contributed to malnutrition in some areas. To help overcome this problem this study had the aim of producing lines of sweet potato with increased nutritional values. Two varieties, Beauregard and LO322, were selected for study as they have a good flavour and a high beta-carotene content. The conditions for the tissue culture of these varieties were determined by altering the mineral and hormonal composition of the culture medium. Increases in nutritional composition were induced by treating calli with mutagenic agents which included : colchicine, ethylmethanesulphonate, UV radiation and two levels of gamma radiation. Putative mutants with reduced feedback inhibition in the pathways which lead to the synthesis of the aspartate amino acids were selected by placing calli on media containing increasing concentrations of lysine and threonine. During the final stage of the selection process, calli were placed on a medium without the addition of selection agents. The results from the tissue culture study suggest that media, 2, 4-D and explant size affect callus growth. MSMA medium (a modified Murashige and Skoog medium) was the most suitable for growing the callus of Beauregard whilst modified White's medium (MW) was better for the growth of LO322 calli. The most prolific callus growth was exhibited by explants of the cultivar Beauregard when placed on MSMA medium. This combination was used to determine the potential of mutagenic treatments to improve the nutritional qualities of the sweet potato. Results from treatments with mutagenic agents showed that all mutagens used had the capability of increasing the soluble protein content of callus. These treatments also had the capacity to increase the concentration of aspartate and other amino acids. Of the mutagens trialed, a treatment with 500 rad gamma radiation appears to be the most suitable for increasing protein and amino acid concentrations. Therefore, once the conditions for regeneration of shoots from calli have been determined this study suggests that it should be possible to produce lines of sweet potato with increased nutritional values using this agent / Master of Science (Hons)

Environmental and political concerns centered on energy use from gasoline have led to a great deal of research on ethanol production. The goal of this thesis is to determine if it is profitable to produce ethanol in Texas using sweet sorghum juice. Four different areas, Moore, Hill, Willacy, and Wharton Counties, using two feedstock alternatives, sweet sorghum only and sweet sorghum and corn, will be analyzed using Monte Carlo simulation to determine the probability of economic success. Economic returns to the farmers in the form of a contract price for the average sweet sorghum yield per acre in each study area and to the ethanol plant buying sweet sorghum at the contract price will be simulated and ranked. The calculated sweet sorghum contract prices offered to farmers are $9.94, $11.44, $29.98, and $36.21 per ton in Wharton, Willacy, Moore, and Hill Counties, respectively. The contract prices are equal to the next most profitable crop returns or ten percent more than the total cost to produce sweet sorghum in the study area. The wide variation in the price is due to competing crop returns and the sweet sorghum growing season. Ethanol production using sweet sorghum and corn is the most profitable alternative analyzed for an ethanol plant. A Moore County ethanol plant has the highest average net present value of $492.39 million and is most preferred overall when using sweet sorghum and corn to produce ethanol. Sweet sorghum ethanol production is most profitable in Willacy County but is not economically successful with an average net present value of $-11.06 million. Ethanol production in Hill County is least preferred with an average net present value of $-712.00 and $48.40 million when using sweet sorghum only and sweet sorghum and corn, respectively. Producing unsubsidized ethanol from sweet sorghum juice alone is not profitable in Texas. Sweet sorghum ethanol supplemented by grain is more economical but would not be as profitable as producing ethanol from only grain in the Texas Panhandle. Farmers profit on average from contract prices for sweet sorghum when prices cover total production costs for the crop.

Thesis (Th.M.)--Dallas Theological Seminary, 2008. / Description based on print version record. Includes bibliographical references (leaves [56]-61).

Thesis--PlanA (M.S.)--University of Wisconsin--Stout, 2000. / Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1959) no. 7, p. 1510-1511. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 76-78).

This study examines the feasibility of producing sweet sorghum as an ethanol feedstock in Mississippi. An enterprise budgeting system is used along with estimates of transportation costs to estimate farmers’ breakeven costs for producing and delivering sweet sorghum biomass. This breakeven cost for the farmer, along with breakeven costs for the producer based on wholesale ethanol price, production costs, and transportation and marketing costs for the refined ethanol, is used to estimate the amounts that farmers and ethanol producers would be willing to accept (WTA) and willing to pay (WTP), respectively, for sweet sorghum biomass. These WTA and WTP estimates are analyzed by varying key factors in the biomass and ethanol production processes. Deterministic and stochastic models are used to estimate profits for sweet sorghum and competing crops in two representative counties in Mississippi, with sweet sorghum consistently yielding negative per-acre profits in both counties.