Impact of Drought On Bioenergy Sorghum Production.

A suite of bioenergy feedstocks will be developed to meet the emerging biomass-based energy economy.  This study compared dry matter yield of two biomass sorghums cultivars (HBS-200 and 201) and dry matter yield and juice yield of one sweet sorghum cultivar (SS-M81E) grown in typical precipitation years (2010, 2011) and one exceptional drought year (2012).  Sorghums were sown at the University of Missouri’s Southwest Center (SWC) and Horticulture and Agroforestry Research Center (HARC).  At SWC, HBS-200 yielded 8.9, 7.7, and 7.7 Mg DM ha^-1, HBS-201 yielded 6.6, 7.9, and 10.7 Mg DM ha^-1, and SS-M81E yielded 7.7, 11.1, and 11.6 Mg DM ha^-1 in 2010, 2011, and 2012, respectively.  At HARC, HBS-200 yielded 20.0, 20.7, and 19.0 Mg DM ha^-1, HBS-201 yielded 19.1, 18.0, 19.9 Mg DM ha^-1, and SS-M81E yielded 20.4, 16.6, and 15.7 Mg DM ha^-1 in 2010, 2011, and 2012, respectively. Sweet sorghum juice yield was similar across locations and averaged 13.9 Ml ha^-1 (2010), 16.2 Ml ha^-1 (2011), and 1.87 Ml ha^-1 (2012).  Biomass yields were greater at HARC each year than at SWC, but there were no differences between years at either location.  Juice yields in 2010 and 2011 were greater than those in 2012. Dry matter yields in drought and in normal precipitation years were similar, suggesting that the examined genotypes are well adapted to marginal lands that may be subjected to drought.  However, sweet sorghum juice yield is reduced by drought and may be considerably less in years with less than adequate rainfall.