Resistance and tolerance to Sclerotinia stem rot in selected short season soybean cultivars in Canada.
Xue, A.G., Rioux, S., Morrison, M.J., Chen, Y., Zhang, J.X., and Yan, W. (2010). "Resistance and tolerance to Sclerotinia stem rot in selected short season soybean cultivars in Canada.", The Americas Journal of Plant Science and Biotechnology, 4(Spec. Issue 2), pp. 48-54.
Fifteen short-season soybean cultivars released in Canada from 1934 to 2000 were evaluated under inoculated field conditions for resistance and tolerance to Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum, in Saint-Bruno, Québec in 2001, 2002 and 2003. Resistance to SSR was measured by the disease incidence, the severity, a disease severity index, the area under the disease progress curve, and tolerance by the reduction of yield and thousand seed weight (TSW) compared to a non-inoculated control. Significant differences in cultivar responses were found for all parameters. Averaged across the test years, ‘AC Harmony’, ‘Maple Arrow’, ‘Maple Glen’, ‘Maple Ridge’, and ‘AC Orford’, released after 1976, were among the most resistant cultivars based on their disease responses and were significantly better than ‘Capital’, ‘Comet’, ‘Flambeau’ and ‘Mandarin’, released before 1953, suggesting that newer cultivars are more resistant to the disease than older ones. The disease reduced yield by approximately 7-45% and TSW by < 4%. ‘Altona’, ‘Crest’, ‘Mandarin’, ‘Maple Glen’, ‘Maple Ridge’, ‘Pagoda’, and ‘Portage’ were among the most tolerant cultivars, with yield reduced by <18%, and were significantly better than ‘AC Harmony’, ‘Capital’, ‘Comet’, and ‘Flambeau’, with yields reduced by >33%. ‘Maple Glen’ and ‘Maple Ridge’ were the only cultivars with high levels of both resistance and tolerance. The four disease parameters were highly correlated (r ≥ 0.98, P < 0.01), suggesting that a single measurement should be sufficient. All disease parameters were negatively correlated with yield and TSW under inoculation (r ≥ 0.36, P < 0.05) but not correlated with yield and TSW reduction, suggesting that resistance and tolerance to SSR are two separately inherited traits in soybean.
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