Dissertation
WATER AND SOIL QUALITY MANAGEMENT FOR ROOT HEALTH AND MANAGEMENT OF VERTICILLIUM WILT IN POTATO
Washington State University
Doctor of Philosophy (PhD), Washington State University
07/2025
DOI:
https://doi.org/10.7273/000007903
Abstract
This dissertation investigates the use of organic amendments and irrigation strategies to improve soil health, root development, water retention, and disease suppression in potato (Solanum tuberosum L.) production. The work integrates field experiments, laboratory measurements, and in vitro evaluations to assess soil physical, chemical, biological, and plant-based responses to different soil management approaches. The first study investigated the impact of mustard green manure (MGM), organic compost (OC), compost tea (CT), and NPK fertilizer under two irrigation regimes (2 liters every 2 days and 4 liters every 4 days), with and without V. dahliae inoculation on potato growth, soil quality, and verticillium wilt. MGM significantly enhanced root growth and increased tuber yield by 14.5% compared to NPK, while reducing verticillium wilt severity by 53.3%. The second study focused on the hydrological effects of these amendments by measuring volumetric water content in situ and modeling soil water retention characteristics using Hyprop analysis. OC and MGM improved soil physical properties, water content, and plant available water. The third study evaluated in vitro the effect of eight different CTs brewed at 3, 6, and 10 days on the colony growth of Verticillium dahliae. The pure fungal culture was exposed to each CT in both unsterilized and filter-sterilized conditions by both direct and volatile exposure. CTs inhibited mycelial growth up to 90.1% via direct exposure and 71.7% via volatile effects, with peak efficacy observed at 6 days of brewing. Sterilized CTs showed reduced but still notable suppression with direct exposure, but not volatile effects. The findings of this dissertation highlight the effectiveness of integrating organic amendments with optimized irrigation strategies to enhance soil quality and crop productivity in sandy soils. Compost teas exhibit strong potential as sustainable biocontrol agents against V. dahliae.
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Details
- Title
- WATER AND SOIL QUALITY MANAGEMENT FOR ROOT HEALTH AND MANAGEMENT OF VERTICILLIUM WILT IN POTATO
- Creators
- HATEM M. SAEED YOUNES
- Contributors
- Lynne A Carpenter-Boggs (Chair)Haly L Neely (Committee Member)Chakradhar Mattupalli (Committee Member)Claire L Phillips (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Crop and Soil Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 140
- Identifiers
- 99901299292101842
- Language
- English
- Resource Type
- Dissertation