Harvest Date Effects on Biomass Yield and Quality of New Energycane (Saccharum hybrids) Genotypes In the Southeastern USA.

Energycane (Saccharum hyb.) is a promising source of bioenergy for the Southeast, as it can be used to produce sugar, lignocellulosic feedstock, or both.  A cold-hardy parent of energycane allows it to be grown at latitudes farther north than sugarcane (Saccharum officinarum).  Management strategies which maximize energy output and biomass quality need to be developed, and new cultivars need to be evaluated in various environments.  Nine energycane entries (Ho 01-07, Ho 06-9001, Ho 06-9002, Ho 96-988, L 99-233, Ho 02-144, Ho 02-147, Ho 00-961, and US 72-114) were planted at Tifton, GA in early fall, 2007 in a randomized complete block design with four replications.  Through fall and winter in 2008, moisture content, nitrogen content, and ash content of the energycane biomass was sampled at monthly intervals to determine the effects of delayed harvest on these traits.  Moisture decreased only slightly until very late in the winter, though varietal differences were significant.  Nitrogen content tended to decrease from October to November, but changed little after that, while ash content decreased until December, and then appeared to increase slightly.  Sugar content (°Brix) was monitored monthly in 2008 and 2009, and total biomass yield was harvested in both years.  Sugar content tended to peak around the time of first frost.  L99-233 and Ho 96-988 had the highest °Brix, peaking around 20% in both years, but these entries also had the lowest biomass.  Entry by year interactions were observed for biomass yield.  The highest yield was achieved in the 2009 season by Ho 06-9002 (48.9 Mg DM/ha).  Fiber quality attributes and conversion efficiency of the biomass for cellulosic ethanol are also being evaluated, and theoretical ethanol yields can then be calculated based on these data.  The monthly evaluation of biomass quality will be repeated in 2010.