Typescript (photocopy). / Digitized by Kansas Correctional Industries

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The Fall Armyworm is a serious pest of many crops throughout most of the Western Hemisphere particularly those belonging to the family Gramineae. This pest is usually controlled by insecticides which, however, cause many health and environmental problems. Although a rich bank of sorgum germplasm occurs in Yemen, no effort has been made to identify the Yemeni cultivars which might express resistance to armyworm attack. There is very little information to show at what time of the growing season and at what planting stage the sorghum cultivars are most susceptible to armyworms. Therefore, eight Yemeni and two American sorghum cultivars were planted in Tucson, Arizona, during 1983 and 1984. The experimental design was a randomized complete block arranged in split-split plots with four replications. The main plots were the varieties, and subplots were two planting dates and two infestation times. The plants were artificially infested with laboratory reared, first instar larvae. Infestation consisted of five larvae per plant in 1983 and ten in 1984. Results demonstrate the 'IBB' and 'TURBA' received the least leaf damage and 'SGIRL-MR1' and 'ALBAIDA' received the most in 1983. However, during 1984, 'TURBA' and 'HAIDRAN' showed the greatest degree of resistance and 'SGIRL-MR1', 'AMRAN', 'ALMAHWIT', and 'ALBAIDA' the least.

Several crops are being touted as a renewable energy source. Sweet sorghum is adapted to many areas, grows relatively rapidly, has moderate water and nutrient requirements, and develops high levels of fermentables. A long term supply of fermentables is needed to make ethanol production economically feasible. Short term availability of fermentables results in unfavorable returns from investments in equipment and crop production. Two planting dates (15 May and 1 June) and eight harvest dates (30 Sep. to 15 Mar.) were used in efforts to to extend the availability of sweet sorghum fermentables. Respiration of sweet sorghum tissue was measured with an infrared gas analyzer before and after freezing to quantify loss of fermentables associated with delayed harvests. Vital stains were used before and after freezing to estimate cell mortality. No significant difference was found in the level of fermentables in sorghum from the two planting dates. Delay-ing harvest caused fermentables to decline significantly (30%) by mid-November and to continue to drop through March. Respiration dropped 90% after exposure to -8 C, but resumed the same rate after 1 week. Vital stai!1ing showed cells die upon freezing. Relatively high respiration rates in the dead tissue suggests saprophytic microbes are responsible for the large decline in fermentables after freezing. Eleven cultivars and lines were tested for yield of fermentables. Wray was superior in yield of fermentables, while Sumac and Sugardrip were inferior. / Master of Science