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Inheritance of Partial Resistance to Black Root Rot in Burley Tobacco. C. A. Wilkinson, Assistant Professor, Southern Piedmont Agricultural Experiment Station, Virginia Polytechnic Institute and State University, Blackstone 23824; R. C. Rufty, Associate Professor, Department of Crop Science, Box 7620, and H. D. Shew, Associate Professor, Department of Plant Pathology, Box 7616, North Carolina State University, Raleigh 27695. Plant Dis. 75:889-892. Accepted for publication 11 March 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0889.

Two generation mean analyses were used to assess the inheritance of partial resistance to black root rot in burley tobacco. A cultivar moderately resistant to black root rot, KY 14, was crossed with a cultivar with low resistance, Burley 21, and with a susceptible cultivar, Judy’s Pride. Five-week-old seedlings of the parental, F1, F2, and both backcross generations for each cross were transplanted into soil infested with 100 chlamydospores of Thielaviopsis basicola per gram of soil mixture and grown in the greenhouse at 21 C. Percent root necrosis was estimated 3 wk after transplanting. Dominance gene effects were significant and negative in the KY 14 × Burley 21 cross, whereas additive gene effects were significant in the KY 14 × Judy’s Pride cross. Epistatic effects were significant in both crosses. Transgressive segregants were identified that may be used in a recurrent selection program to increase levels of resistance to black root rot in burley tobacco.

Additional keywords: Nicotiana tabacum