Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 14, 2000
Publication Date: N/A
Technical Abstract: Sclerotinia stem rot is a soybean disease caused by Sclerotinia sclerotiorum. Current cultivars lack the desired level of resistance to this pathogen. The objective of this research is to determine the effectiveness of selection for resistance to Sclerotinia stem rot by classifying inoculated F2 or F3 single plants. Four crosses, with at least one parent having resistance to S. sclerotiorum were used. In 1998, between 110 and 250 plants per cross were planted in the field and inoculated with S. sclerotiorum mycelia. Plants were misted every 30 minutes during daylight hours from flowering until maturity. Plants from two crosses were in the F2 generation and in the F3 generation for the other two crosses. At maturity, plants were classified as resistant (no infection), moderately resistant (only branches showing lesions), moderately susceptible (lesions on the main stem and branches), and susceptible (lesions on the main stem resulting in plant death). Thirteen plants were selected to represent each class and the resulting F3 or F4 families were planted in 3 replications of hill plots in 1999 under the same conditions as in 1998. Individual plants in each hill were scored as in 1998. Sufficient seeds were available from the original plants from two crosses to repeat the replicated experiment in 2000.