Interspecies Variation of Nonstructural Carbohydrates and Canopy Hyperspectral Reflectance in Perennial Cool Season Grasses.
Duli Zhao, Patrick Starks, Bryan Kindiger, and Charles MacKown. USDA-ARS, Grazinglands Research Laboratory, 7207 W Cheyenne St, El Reno, OK 73036
Forage nonstructural carbohydrate (NSC) concentration is an important indicator of forage quality. Performance of cattle fed forage containing high NSC concentration is improved, but horses fed forage with high levels of NSC enriched with fructans can promote laminitis. Therefore, knowledge of NSC variation among grass germplasm is one element to consider in developing a successful forage and livestock management program. An experiment was conducted in 2004 and 2005 at the USDA-ARS, Grazinglands Research Laboratory, El Reno, OK to investigate concentrations of glucose, fructose, sucrose, fructans, and starch in 13 cool-season grass entries from five plant species, as well as their canopy hyperspectral reflectance at the heading stage. Entries from tall fescue (Festuca arundinacea L. cv. Carmine, Dovey, Kentucky 31, and Maximize), Festulolium (F. arundinacea x L. multiflorum, cv. Felina and Hykor), tall wheatgrass (Elytrigia elongate, cv. Jose), intermediate wheatgrass (Elytrigia intermedia, cv. Luna and Manska), and smooth bromegrass (Bromus inermis, cv. Lincoln and three populations (Lincoln YD, NE B1-2-C0, and NE B1-2-C2) developed at the USDA-ARS, Lincoln, NE) were established in 2000 with a plot size of 1.5 x 6.0 m. The experiment was a complete block design with three replicates. Total NSC at heading ranged from 70 to 112 g kg-1 dry wt. among the 13 entries. Smooth bromegrass had the highest and tall wheatgrass the lowest total NSC concentration, but changes in the fraction of each carbohydrate in total NSC were relatively small among the five species. Averaged across the entries, glucose, fructose, sucrose, fructan, and starch accounted for 14, 10, 15, 38, and 23% of total NSC, respectively. The greatest variation of canopy reflectance in 675-nm waveband was detected among the 13 entries. The NSC information from this study can help breeders and producers select appropriate cool-season grass varieties for livestock.