Influence of midsummer planting dates on ethanol production potential of sweet sorghum.

摘要

Sweet sorghum [Sorghum bicolor (L.) Moench] is one of a few promising energy crops that has multiple uses and is adapted to a wide range of growing conditions. Thus, sweet sorghum may be an attractive alternative to soybean [Glycine max (L.) Merr.] in some wheat (Triticum aestivum L.)-soybean double-cropping systems. Twelve sweet sorghum genotypes differing in maturity were planted in central Missouri in mid- to late June in 2008 and 2009 and evaluated for bioenergy traits. Further, six genotypes were planted in early July and mid-July to assess the impact of delayed planting. Sugar concentration (brix), stem juice yield, fermentable sugar yield, bagasse yield, and estimated ethanol yields differed among cultivars and planting dates. Estimated ethanol yields from bagasse exceeded those from stem juice for all cultivars and planting dates by an average of 2997 L ha-1 across cultivars. Delaying planting from mid-June to early July and mid-July reduced the average estimated total ethanol yields for six cultivars from 5189 to 3852 and 2808 L ha-1, respectively. For the first two planting dates, Keller and Topper 76-6 were among the top three cultivars for estimated total ethanol yields, but for the third planting date, Umbrella produced the largest estimated total ethanol yields. Large amounts of bagasse and juice with good sugar content can be produced when sweet sorghum is planted in mid- to late June, and while productivity declines with later plantings, sweet sorghum may still produce >2800 L ethanol ha-1 when planted in mid-July.