Mariana Souza: Final Dissertation Defense
March 21, 2025 9:00AM - 10:00AM
Members of the Examining Committee and their Department:
- Dr. Alejandro Rojas - Department of Plant, Soil and Microbial Sciences
- Dr. Martin Chilvers - Department of Plant, Soil and Microbial Sciences
- Dr. Sarah Lebeis - Department of Plant, Soil and Microbial Sciences
ABSTRACT
Cotton is one of the most significant crops primarily grown worldwide for fiber, feed, and oil production. In the United States, it is primarily cultivated in the ‘Cotton Belt’, a region spanning from Virginia to California and covering approximately 10 million acres. In Arkansas, where cotton is typically grown from late April to October, the crop is susceptible to various fungal diseases that can reduce both lint quality and yield. Among the main diseases of economic importance for the cotton crop, the seedling disease complex is a significant global issue affecting the establishment and production of cotton stands. It refers to a range of diseases, primarily caused by Pythium spp., Rhizoctonia solani, Fusarium spp., and Thielaviopsis basicola(Berkeleyomyces basicola), that compromise cottonseed germination and seedlings' emergence, survival, and development. Fungicide seed treatments are a key tool in managing cotton seedling diseases, offering critical protection against soilborne and seedborne pathogens. However, their effectiveness depends on the composition and prevalence of pathogen populations, which vary annually and regionally, as well as environmental conditions. The objectives of this study were to evaluate the efficacy of different fungicide seed treatments in improving seedling emergence and survival across multiple years and locations in cotton fields in Arkansas. Additionally, we aimed to characterize the soil- and root-associated microbial communities in cotton, investigating how microbial composition varies by location, year, and seed treatment. For that, our project adopts a multidisciplinary approach, combining field trials, bioassays, culture-based approaches, and metabarcoding to characterize soil and seedling communities. By addressing these critical research questions, our work has the potential to contribute significantly to the development of more effective disease control strategies for cotton seedling diseases.
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