The sugar, biomass and biofuel potential of temperate by tropical maize hybrids

Abstract

The demand for biofuels has created a market for feedstocks to meet future energy requirements. Temperate 9 tropical maize (Zea mays L.) hybrids, which combine high biomass and fermentable stalk sugars, have yet to be considered as a biomass feedstock. Our objective was to evaluate biological potential, genetic variability and impact of nitrogen (N) on biomass, stalk sugar, and biofuel potential of temperate 9 tropical maize (TTM) hybrids. Twelve TTM hybrids, two grain and silage hybrids were grown in 2008, followed in 2009 by seven earshoot-bagged TTM hybrids. In both years, they were grown with and without supplemental N (202 kg ha À1 ) in Champaign, IL. Plants were sampled for total and partitioned biomass, and analyzed for concentration and content of sugar. The TTM hybrids were 40% taller, exhibited later reproductive maturity, greater flowering asynchrony, and remained green longer. All hybrids responded to supplemental N by producing more biomass and grain, a lower percent of biomass partitioned to stalk and leaf, whereas TTM also had a decreased concentration of sugar. Total average biomass yields were 24 Mg ha À1 for both the TTM and grain hybrids. However, TTM partitioned 50% more biomass to the stalk and produced 50% more sugar, and had less than half the grain of the commercial hybrids, indicating grain production and sugar accumulation are inversely related. When grain formation was prevented by earshoot bagging, TTM hybrids produced, without supplemental N fertilizer, an average of 4024 kg ha À1 of sugar, which was three-to four-fold greater than the non earshoot-bagged TTM and ear removed hybrid. Calculated estimates for ethanol production, considering the potential from sugar, stover and grain, indicate TTM can yield nearly the amount of ethanol per hectare as modern grain hybrids, but with a decreased requirement for supplemental fertilizer N.

Production, carbon and nitrogen in stover fractions of corn ( Zea mays L.) in response to cultivar development

“…This suggests changes in the amount of major plant constituents such as lignin, cellulose, and hemicellulose. Similar results were noted for leaves, although differences were smaller than in stalks probably due to large reserve storage capacity in stalks (White et al, 2012). Furthermore, the higher C concentration in stalks was expected since these cultivars seem to favor strengthening these structures to support the weight of ears; this was especially true for single cross hybrids that combine small size with high production (Duvick et al, 2004;Santos et al, 2012).…”

“…That is, double cross hybrids and triple cross hybrids offset the effect of drought on cob production by increasing stalk and leaf production, which practically does not occur with the single cross hybrids. This increase is due to alterations in the source/sink photoassimilates, given that the reduction in the amount of sinks (grain) may favor photoassimilates storage in stalks and leaves (Lee;Tollenaar, 2007;White et al, 2012). In practical terms, this indicates that certain cultivars have greater secondary use potential (i.e., animal feed or energy production) in case of severe damage to the main use (grain production).…”

Development of a multiple-hybrid population for genome-wide association studies: theoretical consideration and genetic mapping of flowering traits in maize

“…A previous research indicated that temperate-tropical hybrids could adapt to more diverse growing environments than temperate-temperate or tropical-tropical hybrids72. A biofuel potential investigation with 12 temperate-tropical maize and two grain and silage hybrids indicated that temperate-tropical hybrids showed more stalk biomass and 50% more sugar with supplemental fertilizer N, and could produce equivalent ethanol with a small amount of nitrogen fertilizer73.…”

Envisioning the transition to a next‐generation biofuels industry in the US Midwest

“…Nonetheless, stover residues are essentially a no‐cost supplement that can augment yield 2. Varieties of maize and its close relative sorghum that are photoperiod sensitive grow larger, flower later, require minimal N inputs since they produce little or no grain, and can provide as much or even more biomass than Miscanthus in most dry locations 13,15,21–24. Sorghum is grown on about 4.8 million US acres, primarily for livestock grain and forage mainly in the Great Plains states in 2010.…”

“…Photoperiod‐sensitive maize hybrids derived from crosses of tropical and temperate‐adapted varieties are another underexploited source of germplasm for generating varieties optimized for sugar and biomass that give high productivity with low nitrogen inputs (Table 1). 23,24…”