Improved Bioenergy Sorghums for the Southeastern US.

Sweet sorghum is an attractive bioenergy crop for the Southeastern US because of its short establishment time, high biomass potential of both soluble sugars and biomass, limited need for irrigation and fertilizer, tolerance to harsh environments, and compatibility with sugarcane processing. Most of the current high-biomass sweet and forage lines were not selected for bioenergy production and were not developed for use in the SE US, were their production is limited by the presence of the aggressive fungal pathogens and the lack of reliable seed supply. In order to expand the acreage of sweet sorghums in this region, there is a need for short-stature parents for hybrid seed production compatible with mechanized seed harvest and for germplasm with resistance to the prevailing fungal pathogens. We are investigating the relationship between height and stem sugar concentration by comparing sugar concentration in populations of genetically related plants that differ in height. This information will be used for the development of a diverse collection of short-stature parental lines suitable for the production of high-biomass sweet sorghum hybrids.  In addition, we have developed a mapping population derived from crossing  resistant and susceptible cultivars. By evaluating the recombinant inbred lines for disease response, and by genotyping the lines with the use of molecular markers, we will be able to identify the genomic regions responsible for disease resistance. This information can be used for molecular breeding of regionally adapted germplasm, and complements the breeding of enhanced sweet sorghum hybrids.