Growth and fitness components of wild x cultivated Sorghum bicolor (Poaceae) hybrids in Nebraska

Premise of the study: Gene flow from crops to wild relatives has received considerable attention since the advent of genetically modified crops. Numerous researchers have found wild-crop hybrids to be nearly as fit as their wild parents, which suggests that crop genes may persist in wild populations. Components of the ecological fitness of cultivated sorghum, its wild relative, shattercane, and their hybrids have not been studied. METHODS: To assess the potential for gene introgression into shattercane, we crossed cultivated sorghum to a single inbred shattercane line to produce F₁ hybrids and measured growth and several components of ecological fitness in relation to both parents in Nebraska, USA. Key results: Germination of F₁ seeds was similar to that of its shattercane parent except at high temperatures, where it was as sensitive as the sorghum parent. The F₁ grew taller and produced more biomass than either parent, but the F₁ leaf area index was intermediate. Fecundity of the F₁ plant was similar to that of shattercane and much greater than that of cultivated sorghum. CONCLUSIONS: Considering all data, the ecological fitness of shattercane x cultivated sorghum F₁ hybrids may be equivalent to the wild shattercane parent, which suggests that crop genes that are either neutral or beneficial to shattercane would persist in populations within agroecosystems.