Evaluation of Sweet Sorghum Germplasm for the Southeast.

Sweet sorghum [Sorghum bicolor (L.) Moench] has become a favorable biofuel feedstock for ethanol production.  Among the essential traits for successful production and use of sweet sorghum in Southeastern United States for renewable fuel are high biomass, high BRIX, lodging resistance, as well as resistance to fall armyworm [Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)], anthracnose (Colletotrichum sp.) and nematodes (Meloidogyne incognita ). In the present study, 116 sweet sorghum inbred and hybrid lines were evaluated for these traits.  Maturity, plant height, BRIX, fall armyworm damage, and anthracnose occurrence were evaluated in the field.  Fall armyworm injury, maturity and anthracnose disease were assessed using a visual rating scale; plant height was measured in meters; and BRIX values were measured 90 d after each planting.  A preliminary screen of genotypes for susceptibility to M. incognita nematode was conducted in the greenhouse using corn as a susceptible standard. Among selected inbreds, entries PI 146890, PI 641807 and PI 653411 from GRIN had the lowest fall armyworm injury ratings (< 3) and favorable values of four other parameters.  In contrast, hybrids 84-5578 ATx 625 , 84-5580 BTx 625, and inbred PI 196584 had some of highest fall armyworm injury ratings (> 4.5).  PI 155336, PI 583832, and Topper were moderately resistant to anthracnose. Nematode reproduction varied greatly among the sorghum genotypes and ranged from negligible to high [Pf/Pi (final count/inoculum level) from 0.1 to 22.6] with 21 genotypes allowing nematode reproduction levels similar to corn, the susceptible standard.  Numerous inbred lines have been identified as useful parents for improved production and pest resistance in a breeding program for the Southeast.