Document Type

Thesis

Date of Award

7-2004

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Biology

First Advisor

Sunday Fadulu

Abstract

The objective of this study is to determine the effects of elevated UV-B (320 - 290 run) light on Xanthomonas campestris. Xanthomonas campestris is a bacterium that causes a disease commonly known as Black Rot. This disease affects crucifers a large variety of vegetable crops. The disease is easily recognized by the presence of yellow, V-shaped lesions extending inward from the margin of the leaf. The disease progresses, the yellow lesions tum brown and the tissue dies. Veins darken and the mid-rib of leaves tum black within in the infected area. The veins discoloration progresses toward the base of the leaf as the bacteria spread through the leaf veins. Eventually, the bacterium spreads into the main stem. In this study cabbage plants infected with Xanthomonas campestris will be exposed to low doses of U'V-B (320 - 290 run) for short periods of time in a greenhouse. To test the effects on Xanthomonas Campestris two groups of cabbage inoculated with Xanthomonas campestris will be treated with a UV-B (320 - 290 nm) radiation. The treatments will one hour daily for a two-week period, with both groups receiving the . same amount of natural light and irrigation. Nursery and greenhouse crops are the sixth largest agricultural commodity group in the U. S. with a farm gate value $12.1 billion in 1998. The greenhouse crop industry annual growth rate in Texas is 9.3% and in 2001 the industry contributed 1.1 billion dollars to the Texas state economy. This growth is due to increasing urbanization and rapid growth of new residential and commercial developments. Greenhouses also present an environment in which elements such as temperature and sunlight that can be controlled by farmers'. Despite the rapid develop of this industry and its positive economic impact; ..., the greenhouse crop industry faces many obstacles. A major challenge to farmers who grow crops by this alternative method is the constant threat of disease. In a 5-year period, 15% of cabbage fields will be affected with black rot. By developing methods that would otherwise eliminate disease-causing bacteria, it would increase crop production and decrease crops loss.

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