Carbohydrates in Grasses. I. Sugar and Fructosan Composition of the Stem Bases of Several Northern‐Adapted Grasses at Seed Maturity1

Abstract

Extraction of the stem base tissue of timothy, orchardgrass, and redtop at near seed maturity with concentrations of ethanol from 95 to 0% yielded steadily increasing percentages of carbohydrates, indicating a series of fructosans of increasing chain length. Reed canarygrass and Kentucky bluegrass tissue also yielded increasing percentages, but not continuously so. Fructosans in all of the above species were predominantly of long‐chain length. Bromegrass,t all rescue, ryegrass, and quackgrass tissue yielded no additional carbohydrate at low ethanol concentrations, indicating that the fructosans present were relatively short‐chain polymers.Concentration of the ethanol must be considered in separating free sugars from low molecular weight fructosans, or otherwise some of the fructosans may De extracted along with the sugars. Thin layer chromatography showed that 85% ethanol was the most suitable concentration with which to extract the free sugars from the fructosans in those species containing predominantly long‐chain fructosans. With the species containing predominantly short‐chain fructosans, 90% ethanol was most suitable. More dilute ethanol solutions extracted short‐chain fructose polymers along with the glucose, fructose, and sucrose.Glucose, fructose, and sucrose constituted only a small part of the total water‐soluble carbohydrates in all of the grass species. Fructosans were the predominant carbohydrates.