Yield Components in Hybrid versus Inbred Sweet Sorghum

Abstract

Sweet sorghum [Sorghum bicolor (L.) Moench] should be an ideal biofuel crop for the southeastern United States, but the current cultivars are all pure lines, which limits the quantity of seed that can be produced, and this seed cannot be mechanically harvested. Hybrid seed can be easily produced on short‐statured plants, but less is known about other advantages of hybrid sweet sorghum over inbred cultivars. Heterosis in this crop has not been extensively studied in this region. Three female lines and 19 male lines were crossed in a factorial mating design (Design II) experiment. All hybrids and their parents were planted in the field in a randomized complete block experiment in 2012 and again in 2014. The yields of individual components (leaves, panicles, bagasse, and juice) were calculated on the basis of their proportions of total biomass yields. Sugar yields were estimated from juice soluble solids concentration. Late‐flowering lines, including Brandes, M 81E, Mer 76‐3, and Top76‐6, had favorable general combining ability (GCA) effects for sugar yields, and among females, N109A had favorable GCA for reduced lodging percentage. Heterosis for grain yield was observed for many hybrids, but sugar yields were usually similar between inbred male lines and their respective hybrids. Hybrids usually flowered earlier than inbreds, thus producing similar sugar yields in less time. Hybrid sweet sorghum appears to offer a modest yield advantage over the current inbred cultivars.