Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/14/2000
Publication Date: N/A
Technical Abstract: Sclerotinia stem rot (SSR) of soybean has become a major disease in soybean production areas of the Midwestern United States. Partial resistance to SSR has been identified in a few plant introductions. These have been used in crosses for cultivar improvement. Information pertaining to the nature of soybean resistance to SSR is not known. The objective of this study was to determine if the shoot or root is associated with resistance. Partial resistance (NKS1990) and susceptible (Williams 82 and Asgrow 2242) cultivars for different scion and root stock combinations were used. Two grafting techniques, single and double shoot grafts, were used along with self-grafting. After successful grafts were made, cotyledons were inoculated with a plug of fungal mycelium, and plants were incubated in a mist chamber for 23 hours. The area under survival curve (AUSC) was evaluated. A resistant or susceptible response was consistently associated with resistant or susceptible shoots regardless of the root stock and grafting techniques. It was concluded that the shoots and not the roots were responsible for resistance to SSR. These findings will be useful for further studies and provide initial understanding of the resistance mechanism to SSR in soybean.