Developing High Biomass Napiergrass (Pennisetum purpureum) Hybrids with Enhanced Biosafety.

Elephantgrass (Pennisetum purpureum), also known as Napiergrass, is one of the most productive perennial grasses in the tropical and subtropical regions of the world and considered a prime candidate feedstock for lignocellulosic biofuel production in the southern US. However, elephantgrass has some potential for invasiveness due to its production of a vast amount of wind dispersed seeds. New elephantgrass plantings are established from vegetative plant parts. Therefore, unlike most seeded crops, seed production is not necessary for elephantgrass biomass production and its suppression will significantly reduce its potential for invasiveness. Interspecific hybridizations between elephantgrass (2n=4x=28) and pearl millet (2n=2x=14) results in genotypes that display male and/or female sterility due to their triploid (2n=3x=21) nature. Variability in flowering time exists in elephantgrass and selection of late flowering accessions may also suppress the production of seeds since temperature requirements are not met during late flowering period in the southern US. Genetically distant accessions including high-yielding, late-flowering, non-lodging phenotypes were selected as parents in order to maximize heterosis for biomass yield and enhance biosafety. We will present data describing the biomass yield, yield components, biomass composition, flowering time and seed set of selected interspecific and intraspecific hybrids evaluated in replicated field trials.