Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/5/2014
Publication Date: 1/23/2015
Citation: Knoll, J.E., Anderson, W.F. 2015. Heterosis and combining ability for yield components in hybrid sweet sorghum. Sweet Sorghum Association Annual Meeting, Jan. 22-23, 2015, Orlando, FL. (poster)
Interpretive Summary: not required
Technical Abstract: Sweet sorghum (Sorghum bicolor (L.) Moench.) has potential as a multi-purpose biofuel crop in the southeast USA. The sugars from the juice can be easily fermented into ethanol or used to produce other chemicals, while the bagasse could be burned in boilers for energy or used for cellulosic ethanol. The grain and leaf portions could be utilized as livestock feed. Most current cultivars are pure lines that produce little seed on very tall plants, which is a major limitation to development of a sweet sorghum-based biofuel industry. There is a need to develop hybrid seed production using short-statured seed parents. A test was conducted at Tifton, GA to assess heterosis and combining ability for various yield components in sweet sorghum. A Design II mating design was constructed using three male-sterile (A-line) seed parents and 19 males to generate 57 hybrids. The males represent a range of maturities, and include landraces, heirlooms, and improved cultivars. In 2012 and again in 2014 all the hybrids, male parents, and the male-fertile (B-line) versions of the females were planted in a randomized complete block design with two replications. Each plot consisted of two rows. One row was used for sampling, while the other was harvested for total biomass at the end of the season. Juice Brix was sampled bi-weekly to monitor sugar production using a hand-held digital refractometer. At harvest, a sample of three stalks was taken from each plot and separated into leaves, stems, and panicles. The juice was extracted from the stems with a three-roller mill. All components were weighed both fresh and dried. The yield of each component was then estimated based on its proportion of the total biomass yield. Plant height, lodging percentage, and days to anthesis were also recorded. Total biomass yields of hybrids were generally similar to those of their male parents, but hybrids also tended to mature earlier than their male parents. Some hybrids tended to produce more of their biomass as grain. Only M81-E showed positive heterosis for juice Brix in its hybrids. Seed parent N109 had good general combining ability for reduced lodging. Among males, Brandes, M81-E, Mer76-3, N98, and Top76-6 had good general combining ability for reduced lodging. The ability to produce seed on a grain-type seed parent, such as N109, is a significant advantage of hybrid sweet sorghum.