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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION, CHARACTERIZATION, AND EVALUATION OF CROP GENETIC RESOURCES AND ASSOCIATED INFORMATION

Location: Plant Genetic Resources Conservation Unit

Title: Evaluation of sweet sorghum as a feedstock by multiple harvests for sustainable bioenergy production

Authors
item Wang, Ming
item Xin, Zhanguo
item Tonnis, Brandon
item Farrell, Glenn -
item Pinnow, David
item Chen, Zhenbang -
item Davis, Jerry -
item Yu, Jianming -
item Hung, Yen-Con -
item Pederson, Gary

Submitted to: Journal of Sustainable Bioenergy Systems (JSBS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 12, 2012
Publication Date: December 31, 2012
Citation: Wang, M.L., Xin, Z., Tonnis, B.D., Farrell, G., Pinnow, D.L., Chen, Z., Davis, J., Yu, J., Hung, Y., Pederson, G.A. 2012. Evaluation of sweet sorghum as a feedstock by multiple harvests for sustainable bioenergy production. Journal of Sustainable Bioenergy Systems (JSBS). 2:122-137.

Interpretive Summary: Sweet sorghum has become an important feedstock for bioethanol production. Total sugar yield and multiple harvests can directly affect ethanol production cost. Little is known about stem traits and multiple harvests that contribute to sugar yield in sweet sorghum. Stem traits were evaluated from 25 sweet and grain sorghum accessions. Stems were harvested twice at soft-dough stage and squeezed with a hydraulic press. Sugars in the stem juice were quantified with high performance liquid chromatography. Sweet sorghum accessions produced five times more fresh stem weight and dry stem mass (830 g and 164 g) than grain sorghum (150 g and 27g). Sweet sorghum produced a much higher volume of juice and higher yield of sugars (366 ml and 42 g) per stem than grain sorghum (70 ml and 4 g). Significant variability on fresh stem weight (72-1837 g), juice volume (31-753 ml), sugar yield (3-81 g), dry stem mass (14-383 g), and sugar yield/dry stem mass ratio (0.11-0.53) per stem was detected among sweet sorghum accessions. Stem sugar yield was significantly correlated with stem fresh weight and juice volume. Sorghum was harvested twice within one growing season resulting in some sweet sorghum accessions producing double the amount of sugar. Sweet sorghum produced four times dry mass weight (bagasse) of fermentable sugar weight. To reduce feedstock cost, methods have to be developed for efficiently utilizing bagasse. Our results showed high fresh stem weight, high ratio of sugar yield to dry stem mass, and double harvests are prime traits to boost sugar yield. The U.S. sweet sorghum collection needs to be screened for these traits for bioethanol production.

Technical Abstract: Sweet sorghum has become an important feedstock for bioethanol production. Total sugar yield and multiple harvests can directly affect ethanol production cost. Little is known about stem traits and multiple harvests that contribute to sugar yield in sweet sorghum. Stem traits were evaluated from 25 sweet and grain sorghum accessions. Stems were harvested twice at soft-dough stage and squeezed with a hydraulic press. Sugars in the stem juice were quantified with high performance liquid chromatography. Sweet sorghum accessions produced five times more fresh stem weight and dry stem mass (830 g and 164 g) than grain sorghum (150 g and 27g). Sweet sorghum produced a much higher volume of juice and higher yield of sugars (366 ml and 42 g) per stem than grain sorghum (70 ml and 4 g). Significant variability on fresh stem weight (72-1837 g), juice volume (31-753 ml), sugar yield (3-81 g), dry stem mass (14-383 g), and sugar yield/dry stem mass ratio (0.11-0.53) per stem was detected among sweet sorghum accessions. Stem sugar yield was significantly correlated with stem fresh weight and juice volume. Sorghum was harvested twice within one growing season resulting in some sweet sorghum accessions producing double the amount of sugar. Sweet sorghum produced four times dry mass weight (bagasse) of fermentable sugar weight. To reduce feedstock cost, methods have to be developed for efficiently utilizing bagasse. Our results showed high fresh stem weight, high ratio of sugar yield to dry stem mass, and double harvests are prime traits to boost sugar yield. The U.S. sweet sorghum collection needs to be screened for these traits for bioethanol production.

Last Modified: 9/21/2014