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

Abstract

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.

Opportunities for Napier Grass (Pennisetum purpureum) Improvement Using Molecular Genetics

“…Napier grass, with its perennial nature and fast growing characteristics, has been reported to produce a dry matter (DM) yield of up to 78 tons/ha/annum (35-41 tons/ha average) [26]. Rengsirikul et al [27] estimated a maximum ethanol production of 350-460 L/ton DM from Napier grass varieties grown in Thailand, and an estimated ethanol yield of 329 L/ton DM. Lima et al [28] demonstrated that this potential was 6% and 15% higher than for the tropical forages Brachiaria brizantha and Panicum maximum, respectively, around 15% higher than Eucalyptus bark and 17% higher than for sugarcane.…”

“…Napier grass cultivars have been reported to yield around 60 tonnes dry matter/ha/year, with some studies indicating significantly higher yields [26,27]. The yield of Napier grass mainly depends on the type of cultivar used which in turn is influenced by both the environment and management practices employed.…”

“…The performance and yield of Napier grass is heavily influenced by agro-ecology, climatic conditions, management practices and other edaphic factors [27,66]. According to Kebede et al [67], the most significant factor affecting DM production of Napier grass is the environment, followed by genotype by environment interactions and then the genotype.…”

“…The yield of Napier grass mainly depends on the type of cultivar used which in turn is influenced by both the environment and management practices employed. Nevertheless, there are two major categories of Napier grass cultivars based on their morphology, the normal or tall (up to 4-7 m) varieties (for example 'Australiano', 'Bana' and 'French Cameroon') and the dwarf or semi-dwarf (<2 m) varieties (for example 'Mott') [27]. The normal varieties have been reported to produce up to twice as much yield as the dwarf ones [27,63].…”

“…Nevertheless, there are two major categories of Napier grass cultivars based on their morphology, the normal or tall (up to 4-7 m) varieties (for example 'Australiano', 'Bana' and 'French Cameroon') and the dwarf or semi-dwarf (<2 m) varieties (for example 'Mott') [27]. The normal varieties have been reported to produce up to twice as much yield as the dwarf ones [27,63]. However, dwarf varieties also have a number of positive attributes, including enhanced overwintering capacity in the border areas between subtropics and temperate zones, better nutritive value, and ease of management and harvesting [64,65].…”