Biomass Yield, Chemical Composition and Potential Ethanol Yields of 8 Cultivars of Napiergrass (Pennisetum purpureum Schumach.) Harvested 3-Monthly in Central Thailand

Eight cultivars of napiergrass (Pennisetum purpureum Schumach.), namely Dwarf, Muaklek, Bana, Taiwan A148, Common, Wruk wona, Tifton and Kampheng San, were grown in central Thailand in 2008-2009 and biomass yield, chemical composition and theoretical ethanol yield were measured. Harvests were made every 3 months. Biomass yield and cell wall compositions differed significantly (P < 0.05) among cultivars. Tifton produced the highest annual biomass yield at 58.3 t/ha followed by Wruk wona (52.1 t/ha), while the lowest yield of 27.1 t/ha was in Dwarf. Biomass yield varied with season with highest yields in May and lowest in February during the dry season. Cell wall concentrations were higher in the tall cultivars than in the short ones (Dwarf and Muaklek) (P < 0.05). Theoretical ethanol conversion efficiency ranged from 350 to 460 L/t DM among the cultivars following pretreatment with steam explosion. While a number of cultivars showed significant potential for use as biofuels in central Thailand, Tifton seemed to be the most promising.