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Nonstructural carbohydrates in storage tissues of pinegrass (Culumugrostis rubescens Buckl.) consist of sucrose, glucose, fructosan, and starch. The predominant polymer is a long-chain fructosan. An acid-extractable structural carbohydrate appeared to be xylan. Total nonstructural carbohydrates (TNC) of rhizome plus root tissue decreased during May, reached a minimum value during late May to early June, increased until late June, remained constant until late August, and then increased until November. The TNC level of crown tissue was low during May and early June and reached a peak during July and again in the fall. The crude protein concentration of rhizome plus root tissues was relatively constant throughout the season. Rhizome plus roots accumulated the largest amounts of TNC and crude protein. Stored organic compounds, such as carbohydrates, fats, and proteins, serve as food reserves for plants at times when photosynthesis cannot supply sufficient material for maintenance and growth (Trlica 1977, White 1973). These reserves must provide a source of energy and a source of molecules for growth when plants are completely defoliated; however, a definite role in regrowth of partially defoliated plants has not been proved (May 1960, Jameson 1964). In addition to a role for reserves in regrowth of completely defoliated plants, reserves are utilized by perennials during the winter (Menke and Trlica 1981). Root reserves typically decrease following harvest of aerial growth, and this decrease implies a role for reserves in regrowth. Whether or not reserves are used directly for regrowth, reserve level may serve as a measure of plant vigor following grazing (Trlica 1977). Grasses can be classified on the basis of the type of nonstructural carbohydrates (NC) that are accumulated: starch or fructosan accumulators (Smith 1968). Furthermore, they are classified according to the type of structural carbohydrate (SC); xylose is the predominant SC component in fructosan containinggrasses, while glucose is the predominant SC component in starch containing grasses (Ojima and lsawa 1968). Pinegrass (Calamagrostis rubescens Buck].) is an important source of forage on the forest ranges of British Columbia (McLean et al. 1969). Simulated grazing studies have established that pinegrass is most sensitive to herbage removal during July (Freyman 1970, Stout et al. l980), and that a pinegrass stand will deteriorate under simulated intensive grazing practices, such as clipping biweekly from May I5 to September I5 to a stubble height of 5 or IO cm (heavy and moderate grazing intensities respectively) (Stout et al. 1981). The objectives of this study were to determine: (I) type of carbohydrates stored: (2) seasonal pattern of carbohydrate and crude protein levels; and (3) morphological distribution of carbohydrate and protein reserves in pinegrass. D.G. Stout and B. Brooke are with Agriculture Canada. Research Station. 3015 Ord Road, Kamloops. B.C. V2B 8A9: M. Suzuki is with Agrictthure Canada. Rewarch Station. Charlottetown. Prince Edwards Island. CIA 7M8. Manuscrq received March 12. 1982. 440 Material and Methods Identification of the Carbohydrate Storage Form(s) in Pinegrass Pinegrass rhizomes were collected from the field in October and planted in 4-liter plastic pots containing loam, sand, and peat in the ratio of 1: l:l. Tiller growth and development occurred during a 3-month period in a growth chamber with a l6-hr photoperiod, a light energy of 90 Wme2 provided by fluorescent (Vita-Lite, DuroTest Corp., U.S.A.) and incandescent lamps, a day temperature of 20 f I C, and a night temperature of l8f I C. Tillers in I2 pots were then clipped to a 5-cm stubble height at 2-wk intervals during a 6-wk period. Tillers in 12 other pots received no clipping treatment during the 6-wk period. Following the 6-wk treatment period, 3 replicates of each treatment were harvested; each replicate consisted of 4 pots. A completely random design was used for this experiment. Plant material was harvested and divided into crown and rhizome plus root fractions. Crown tissue was defined as the I.5 cm portion of the tiller above its point of attachment to the rhizome. The crown sample included the growing point plus about 8 stem nodes, the attached scale leaves, and sheaths of at least 4 aerial leaves. The rhizome plus root fraction contained the rhizome and all of the attached fibrous root material that could be collected. Crown and rhizome plus root tissues were washed with cold water, freeze-dried, and ground to pass through a 40-mesh screen. Reducing sugars, total sugars, fructosans, starch, and H&04 extractable structural carbohydrates (SC) were then measured. To characterize the relative contribution of rhizomes and roots to the rhizome plus root tissue, on 2 dates the rhizome plus root tissue was separated into rhizome and fibrous root tissues following washing. Dry weight, TNC and crude protein were determined for each type of tissue. Similar chemical measurements were also made on crown tissue harvested from a native stand of pinegrass in May, June, and October, 1978. For this study, tissue samples from 2 of the 6 replicates of the seasonal trend study were used. Seasonal Trend of TNC and Crude Protein in Pinegrass Crowns and Rhizome Plus Roots In 1978, a 0.2-ha area of land immediately adjacent to the Poison Creek study site (Stout et al. 1980) was fenced to keep out cattle. Six 20 m2 plots were identified within the 0.2 ha area. Samples were collected on 20 dates from May 15, 1978, to October 23, 1979. Pinegrass sods (to a depth of IO cm in the mineral soil) were dug from a subplot (0.5 to 0.8 m*) within each 20 m2 plot. The subplots were harvested according to a completely random design. The bulk of the adhering soil was removed from the sods and the plant material was put into plastic bags and transported to the laboratory on ice. Sods were washed with cold water and crown and rhizome plus root samples were prepared as above, with the exception that drying was done in a forced air oven at 6oOC. TNC and crude protein content were then measured. Distribution of Dry Weight, TNC, and Protein in a Pinegrass Tiller On July 16, 1979, four areas (400 to 900 cm2) of pinegrass sods JOURNAL OF RANGE MANAGEMENT 36(4), July 1983

Nonstructural Carbohydrate and Crude Protein in Pinegrass Storage Tissues