Heterosis And Combining Ability Of F-1 Hybrid Sweet Sorghum In Thailand

Sweet sorghum [Sorghum bicolor (L.) Moench] is a sugar-based biofuel crop that is well-suited to tropical environments. Most sweet sorghum cultivars are open-pollinated, but hybrids could offer yield and seed production advantages. Fifteen hybrids were generated among five female and three male parents. The hybrids, parents, and three inbred checks were evaluated for sugar yield and related traits under two environments in Thailand in 2013: Field Crop Research Station at Khon Kaen University, Khon Kaen, and National Corn and Sorghum Research Center, Nakhon Ratchasima. Theoretical sugar yield was positively correlated with juice dissolved solids (Brix), plant height, stalk diameter, biomass yield, stripped stalk yield, and theoretical juice yield. Grain yield was negatively correlated with juice dissolved solids and theoretical sugar yield. Positive heterosis for juice dissolved solids was not observed, though five hybrids had negative mid-parent heterosis for this trait. Positive heterosis for biomass yield, theoretical juice yield, and grain yield was observed in some hybrids. General combining ability was observed for most traits, but specific combining ability (SCA) effects were of greater importance. Overall, the hybrids KKA-11 x BJ248, KKA-11 x KKU40, KKA-139 x BJ248, KKA-14 x KKU40, and KKA-53 x Theis had the greatest SCA for theoretical sugar yield. In producing ethanol from both sugar and grain fractions, two of the hybrids in this study (KKA-11 x BJ248 and KKA-139 x BJ248) could produce approximately 4600 L ha(-1) ethanol in Thailand.