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Breeding Sweet Sorghum for Syrup Production
Department of Plant and Soil Sciences
`Food and Wine' magazine included sorghum syrup among four extraordinary mail-order foods which were worth the treasure hunt. Sweet sorghum syrup production is an alternative income source for small farmers. Over 50% of the syrup producers raise five acres or less of sweet sorghum.
Sorghum producers are looking for new varieties which eliminate some of the deficiencies of currently available varieties while maintaining syrup quality. Attributes which could be improved include early maturity, resistance to red stalk rot and maize dwarf mosaic virus, higher sugar concentration in the stalk juice, and standability. Different sweet sorghum genetic types will be crossed to each other, and the progeny of the crosses will be analyzed for a combination of qualities not available in current varieties. Brix, a measure of sugar concentration, will be used to select sweet sorghum genetic types with new levels of sugar concentration. I anticipate identifying sweet sorghum types with higher levels of sugar and releasing a sweet sorghum variety which will reduce production constraints for sorghum syrup producers.
2010 Project Description
The sweet sorghum breeding project continued. 21 F4:6 lines were tested for a second year at Lexington and Quicksand, KY. Data were collected on heading date, lodging, stem and leaf disease, biomass production, stem juice fraction and juice brix. 116 F4:5 lines were grown for the first year at Lexington, KY. 14 F2 populations were grown at Lexington and individual plants were selected based on early heading date, no lodging, and biomass production as measured by plant height. Two plant introductions, 152771 and 208190, which had been previously selected from a screen of 100 sweet sorghum introductions based on high brix of stem juice, were compared in hybrid combinations with variety Dale. The primary trait of interest was juice brix. Additional sweet x grain sorghum backcrosses and sweet x sweet sorghum F1 crosses were made. Information on the project was presented at the Sweet Sorghum Producers and Processors Association annual meeting in February and at the Robinson Center for Appalachian Resource Sustainability field day in October. Kentucky Foundation Seed Project continued to supply seed of the F1 sterile hybrid KN Morris to sorghum syrup producers in the United States.
Sorghum plant introductions 152771 and 208190 did not produce higher stem juice brix when in hybrid combination with sweet sorghum variety Dale. The higher juice brix identified in those plant introductions was not conditioned by dominant alleles that would have produced higher brix in the F1 hybrid. KN Morris continued to be adopted by sweet sorghum producers. For the second consecutive year the sorghum syrup which won the syrup quality contest at the National Sweet Sorghum Producers and Processors Association meeting was produced from KN Morris.
T.W. Pfeiffer, M.J. Bitzer, J.J. Toy, and J.F. Pedersen. 2010. Heterosis in Sweet Sorghum and Selection of a New Sweet Sorghum Hybrid for Use in Syrup Production in Appalachia. Crop Science 50:1788-1794.