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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #244715
Title: Heterosis in Sweet Sorghum and Selection of a New Sweet Sorghum Hybrid for Use in Syrup

Author
item PREIFFER, T - University Of Kentucky
item BITZER, M - University Of Kentucky
item Toy, John
item Pedersen, Jeffrey

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2010
Publication Date: 6/7/2010
Citation: Preiffer, T.W., Bitzer, M.J., Toy, J.J., Pedersen, J.F. 2010. Heterosis in Sweet Sorghum and Selection of a New Sweet Sorghum Hybrid for Use in Syrup. Crop Science. doi: 10.2135/cropsci2009.09.0475.

Interpretive Summary: Hybrid vigor is well known in sorghum and nearly all commercial grain and forage sorghums produced in the USA are hybrids. However sweet sorghum, which is used for the production of syrup for human consumption and which has potential for the production of bioenergy, is currently produced using pureline varieties. Recent development of cytoplasmic male sterile sweet sorghum lines now allows generation of sweet sorghum hybrids for research and commercial applications. Such male sterility may also affect how photosynthate is stored creating the potential to increase sugar content of sweet sorghum stalks. An experiment was conducted at the University of Kentucky to quantify hybrid vigor for several sweet sorghum traits, and to determine if a novel source of cytoplasmic male-sterilty, A3, increased sugar content and yield. Sweet sorghum hybrids produced greater stalk yield due to taller plants with greater stem diameter. Juice fraction and juice composition remained relatively unchanged. Only six hybrids showed positive heterosis for brix, an indirect measure of sugar content. The greater juice yield and higher sugar content of selected hybrids such as A3 N100 x Dale could produce more total syrup or ethanol than current pureline sweet sorghum varieties.

Technical Abstract: Although heterosis is well established in grain and forage sorghum [Sorghum bicolor (L.) Moench], reports of heterosis in sweet sorghum are limited to results from grain sorghum x sweet sorghum hybrids. Recent development of cytoplasmic male-sterile sweet sorghum lines allows creation of sweet sorghum hybrids for research and commercial applications. Such male-sterility may also affect the allocation of photosynthate to different plant parts creating the potential increase of sugar content in sweet sorghum stems by eliminating seed as a carbohydrate sink. For this application, A3 cytoplasmic male sterility has strong potential for eliminating seed set. The objectives of this study were to: compare performance of A3 cytoplasmic male-sterile lines and A3 cytoplasmic male-sterile hybrids to fertile B3 counterparts and to each other. A3 cytoplasmic male-sterile ‘Dale’, ‘Wray’, ‘Sugar Drip’, and N100 were crossed in all combinations to their male-fertile counterparts to generate hybrids, resulting in 20 genotypes including the male-fertile lines. The 20 genotypes were grown in a randomized complete block in 2004 and 2005 at Lexington, Kentucky. Male-sterile hybrids and lines had higher brix than male-fertile lines. Hybrids produced greater stalk yield due to taller plants with greater stem diameter. Juice fraction and juice composition remained relatively unchanged. Only six hybrids showed positive heterosis for brix. The greater juice yield and higher sugar content of selected hybrids such as A3 N100 x Dale could produce more total syrup or ethanol than current pureline sweet sorghum varieties.