Rhizoctonia solani causes stem rot and target spot of greenhouse-produced tobacco seedlings. No fungicides are registered for control of these diseases, so sanitation is the primary disease management strategy. Seedling resistance to R. solani has not been characterized in current tobacco germplasm. The objective of this study was to screen seedlings of a diverse array of accessions, including several classes of tobacco cultivars and related Nicotiana species for resistance to a stem rot (AG-4) and a target spot isolate (AG-3) of R. solani. Further studies were conducted to determine if the resistance identified is heritable. Experiments were conducted in environmentally controlled growth chambers at the NCSU phytotron. Tobacco seedlings were grown in polystyrene trays floating on a nutrient solution to replicate greenhouse growth conditions. Approximately two weeks after germination, rice grains colonized by R. solani were placed on the surface of the growth medium to infest the medium. Symptoms, including death, stem lesions, and target spot lesions, were observed for 42 days after infesting the soil for stem rot and 56 days for target spot. Data were analyzed using a GLM procedure in SAS (SAS Institute, Cary, NC). Significant differences were observed among the accessions in level of resistance to stem rot and target spot. Disease incidence ranged from 12.5 to 100% for stem rot and 6.2 to 97.9% for target spot. This wide range of disease incidence observed among accessions for both diseases indicates that useful levels of resistance may exist to both diseases and may be useful in future breeding efforts.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-02032004-092716 |
| Date | 06 February 2004 |
| Creators | Elliott, Patsy Elizabeth |
| Contributors | H. David Shew, Verne Sisson, Jennifer Levin |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-02032004-092716/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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