Ratoon cold tolerance of Pennisetum, Erianthus, and Saccharum bioenergy feedstocks

Use of perennial bioenergy grasses would be enhanced if they produced sustainable ratoon crops across a wide geographic region. Our objective was to compare ratoon cold tolerance (defined as shoot emergence during the first-ratoon crop), and plant cane dry mass yield and feedstock quality [acid detergent lignin, cellulose, hemicellulose, total nonstructural carbohydrates (TNC), and combustible energy] of elephantgrass (Pennisetum purpureum), Old World Erianthus (Sacchartun arundinaceum, formerly E. arundinaceus, subsequently referred to as Erianthus), and sugarcane (Saccharum sp. hybrids). The experiment (Test 1) was conducted near Booneville, Arkansas (35.08 degrees N latitude) and consisted of three varieties of elephantgrass and Erianthus, and six of sugarcane, evaluated in plant cane (first year growth, 2008) and first-ratoon (second year growth, 2009). The experiment was repeated in 2009-2010 (Test 2). Absolute minimum air temperatures were -12.7 and -17.3 degrees C in Test 1 and 2, respectively. Second-year emergence in Test 1 was in the order sugarcane = Erianthus (92%) > elephantgrass (25%). In Test 2, sugarcane and Erianthus had 63 and 3% second-year emergence, respectively, whereas elephantgrass shoots did not emerge. Elephantgrass had twice the plant cane yield of the other species. Feedstock quality was generally similar among species, although sugarcane had greater TNC (220 g kg(-1)) than other species (<= 131 g kg(-1)). Poor ratooning of all 12 varieties would limit their use as perennial bioenergy feedstocks in similar environments, however, breeders using germplasm selected under these conditions could ultimately enhance ratoon cold tolerance of commercial sugarcane varieties for more southerly latitudes.