Glucan Yield from Enzymatic Hydrolysis of Big Bluestem as Affected by Ecotype and Planting Location Along the Precipitation Gradient of the Great Plains

Three big bluestem (Andropogon gerardii Vitman) ecotypes from central Kansas (Cedar Bluffs (CDB) and Webster (WEB) populations), eastern Kansas (Konza (KON) and Top of the World (TOW) populations), and Illinois (12Mile (12M) and Fults (FUL) populations), as well as the Kaw cultivar, were harvested from four reciprocal garden planting locations (Colby, Hays, and Manhattan, KS, and Carbondale, IL) and used to study effects of ecotype and planting location on glucan content and glucan yield from enzymatic hydrolysis along the Great Plains precipitation gradient (∼1,200 to 400 mm mean annual precipitation). The populations varied widely in glucan content (31.8–36.5 %), mass recovery (52.0–59.7 %), and glucan recovery (79.0–87.50 %) after acid treatment, efficiency of enzymatic hydrolysis (EEH) (84.6–88.9 %), and glucan mass yield (20.8–29.3 %). Planting location had significant effects on all variables evaluated except EEH. Ecotype had significant effects on glucan recovery, EEH, and glucan mass yield. In addition, interaction between ecotype and planting location also had significant effects on glucan content and glucan mass yield after enzymatic hydrolysis. Planting location had a stronger influence than ecotype and interaction between location and ecotype. Total glucan mass yield of big bluestem (regardless of ecotype) increased as the Great Plains precipitation gradient increased from west to east. Annual precipitation, growing degree days, and potential evapotranspiration in 2010 accounted for 90, 85, and 78 % of the variation in glucan mass yield.