Dissertation
THE INFLUENCE, INTERACTIONS AND MODELLING OF WATER POTENTIAL AND TEMPERATURE ON THE GROWTH OF SOILBORNE PATHOGENS OF WHEAT - FUSARIUM CULMORUM, FUSARIUM PSEUDOGRAMINEARUM, RHIZOCTONIA SOLANI AND RHIZOCTONIA ORYZAE
Doctor of Philosophy (PhD), Washington State University
01/2017
Handle:
https://hdl.handle.net/2376/111183
Abstract
Fusarium crown rot (FCR) caused by Fusarium pseudograminearum (Fp) and F. culmorum (Fc) and Rhizoctonia root rot caused by Rhizoctonia solani AG8 (Rs8) and R. oryzae (Ro), are major soil-borne fungal diseases responsible for economic losses in dryland wheat in the Pacific Northwest region of the United States. This study focuses on exploring the finer details of soil moisture and temperature impacts on these four pathogens and developing models for projecting their growth in response to these variables. Methods were developed using NaCl, KCl and polyethylene glycol to precisely define water potential (WP) treatments at different temperatures. On defined media and sterile wheat straw, the optimum temperature for the mycelial growth and dry weight gain for Fc and Rs8, and Fp and Ro was 20-25°C and 25-30°C, respectively. The optimum WP was -0.3 MPa for both Rhizoctonia spp. and -1 to -2 and -2 to -3 MPa for Fc and Fp, respectively. Macroconidia of Fusarium spp. were capable of germinating across all ranges of WP. Except for Fp, the other three pathogens had different optimum temperatures and WPs for their growth in soil. The optimum temperature and WP for both Rhizoctonia spp. was 10-15°C and -2 MPa, respectively. Fc had a temperature optimum of 10-15°C with a preference for the WP below -5.5 MPa. The optimum temperatures for Fp vary with the WP in the soil. In a greenhouse study, the disease severity of FCR and DNA of Fp in the infected wheat plants was significantly different across all WP treatments and had a strong negative correlation with the median values of the whole column WP. On the other hand, there was no significant difference of DNA and FCR disease score in Fc inoculated columns with the WP levels. Models were developed for projecting pathogen growth in defined nutrient media, soil, and infected plants based on the temperature and WP levels.
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Details
- Title
- THE INFLUENCE, INTERACTIONS AND MODELLING OF WATER POTENTIAL AND TEMPERATURE ON THE GROWTH OF SOILBORNE PATHOGENS OF WHEAT - FUSARIUM CULMORUM, FUSARIUM PSEUDOGRAMINEARUM, RHIZOCTONIA SOLANI AND RHIZOCTONIA ORYZAE
- Creators
- Iqbal Singh Aujla
- Contributors
- Timothy C Paulitz (Advisor)Scot H Hulbert (Committee Member)Xianming Chen (Committee Member)David R Huggins (Committee Member)John T Abatzoglou (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Plant Pathology
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 229
- Identifiers
- 99900581826201842
- Language
- English
- Resource Type
- Dissertation