Published in Crop Sci. 44:2193-2198 (2004).
© 2004 Crop Science Society of America
677 S. Segoe Rd., Madison, WI 53711 USA
FORAGE & GRAZING LANDS
Eastern Bottlebrush Grass Yield, Persistence, and Nutritive Value in the Northeastern USA
Matt A. Sandersona,*,
R. Howard Skinnera,
Martin van der Grintenb and
Jennifer Kujawskic
a USDA-ARS Pasture Systems and Watershed Management Research Unit, Bldg. 3702, Curtin Road, University Park, PA 16802-3702
b USDA-NRCS Plant Materials Center, Big Flats, NY 14830
c Usda-Nrcs
* Corresponding author (mas44{at}psu.edu)
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ABSTRACT
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Introduced (nonnative) species account for nearly all of the forage grasses used in northeastern USA forage systems. We evaluated accessions of the native cool-season species, Eastern bottlebrush grass (Elymus hystrix var. hystrix L.), from the northeastern USA for yield, persistence, plant morphological traits, and nutritive value. Thirteen accessions and one commercial ecotype of bottlebrush grass were transplanted into single-row field plots in late summer of 2000 at Beltsville, MD, Rock Springs, PA, and Big Flats, NY. Two orchardgrass (Dactylis glomerata L.) cultivars were included for reference. Yield, persistence, morphology (leaf width, length, mass, area, and tillers per plant), and nutritive value data were collected during 2001 and 2002. Bottlebrush grass was eliminated by the bluegrass billbug (Sphenophorus parvulus Gyllenhal) at Rock Springs in spring of 2001. At Big Flats and Beltsville, the bottlebrush grass accessions produced as much dry matter per plant as the commercial ecotype. Orchardgrass yielded four times as much dry matter as the mean of all bottlebrush grass entries (102 g vs. 26 g per plant averaged for years and locations). The low productivity of bottlebrush grass resulted from reduced tillering especially during regrowth. There was very little regrowth of bottlebrush grass during late summer in all environments. Survival of bottlebrush grass was 36% during 3 yr vs. 84% for orchardgrass. Differences in nutritive value among accessions were due mainly to differences in leaf-to-stem mass ratio. Eastern bottlebrush grass has limited potential for use as a forage grass in the northeastern USA.
Abbreviations: CP, crude protein • dNDF, digestible neutral detergent fiber • IVTD, in vitro true digestibility • LSR, leaf-to-stem mass ratio • NDF, neutral detergent fiber • SLA, specific leaf area
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INTRODUCTION
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THE COMMONLY USED cool-season forage grasses in the northeastern USA are introduced species. The native grasses most often used in northeastern forage systems are warm-season perennials such as switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman). Interest in the use of native plant species for conservation and production has increased during recent years because of new federal policies related to invasive species, conservation plantings, farm programs, and ecosystem restoration that encourage the use of native plants (Richards et al., 1998; Federal Register, 1999; Booth and Jones, 2001). Almost no information exists on the use of native cool-season grasses as forage species in the northeastern USA.
Eastern bottlebrush grass, a perennial cool-season grass native to the northeastern USA, grows mainly in river valleys and along woodlands (Pohl, 1947; Hitchcock, 1971). A recent review of Elymus species did not include any information on bottlebrush grass (Asay and Jensen, 1996). Virginia wildrye (Elymus virginicus L.) has been evaluated in the northeastern USA in terms of yield, persistence, and nutritive value (Sanderson et al., 2004a, 2004b). Virginia wildrye performed better on a deep soil in New York compared with shallow or sandy soils in Pennsylvania and Maryland, respectively. The nutritive value of Virginia wildrye was comparable to that of orchardgrass; however, orchardgrass was much more productive and persistent.
There is a need for more information on the usefulness of locally adapted native grasses in production, conservation, and other plantings in the northeastern USA. Therefore, we evaluated several northeastern collections of bottlebrush grass for dry matter yield, persistence, morphological characteristics, and nutritive value at three locations.
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MATERIALS AND METHODS
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The experiment was conducted at the USDA-NRCS Plant Materials Center in Big Flats, NY (42°N, 76°54'W, elevation 290 m), the Russell E. Larson Agricultural Research Center at Rock Springs, PA (40°48'N, 77°52'W, elevation 365 m), and the USDA-NRCS National Plant Materials Center in Beltsville, MD (39°02'N, 76°56'W, elevation 36 m) from 2000 to 2002. Soil types were Unadilla silt loam (coarse-silty, mixed, active, mesic Typic Dystrudepts) at Big Flats, Hagerstown silt loam (fine, mixed, semiactive, mesic, Typic Hapludalfs) at Rock Springs, and Iuka sandy loam (coarse, loamy, siliceous, active, acid, thermic, Aquic Udifluvents) at Beltsville. The site at Big Flats was near the Chemung River and a woodland margin. The Beltsville site was in a similar woodland edge setting, but not in a river valley, and was on a gentle slope (2–5%) with an eastern aspect. The Rock Springs plots were on an upland agricultural site. Weather data (Table 1) were recorded at meteorological stations near each site.
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Table 1. Monthly average air temperature and total rainfall at Big Flats, NY, and Beltsville, MD, during 2001 and 2002 compared with the 30-yr average (1961–1990).
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The bottlebrush grass accessions were collected by the USDA-NRCS plant materials centers from several northeastern states in 1998 and 1999 (Table 2). Thirteen accessions and a commercial ecotype (Ernst Conservation Seeds, Meadville, PA) of bottlebrush grass were transplanted into single-row field plots during August 2000 at Rock Springs and Big Flats and September 2000 at Beltsville. Two orchardgrass cultivars (Potomac and Pennlate) were included for reference only. Each entry was established from seed in the greenhouse at the National Plant Materials Center, Beltsville. Entries were hand transplanted into single-row plots of 10 plants per plot. Each plot of 10 plants contained eight experimental plants and a border plant of the commercial ecotype at each end of the row. Border rows of the commercial ecotype alternated with row plots of the accessions. Plants were spaced 30 cm apart within rows, and rows were spaced 30 cm apart. At each location, a plastic weed barrier controlled weeds during establishment. The plastic weed barrier was removed from all plots in March (Beltsville) or April 2001 (Big Flats and Rock Springs) after which weeds were controlled by hand and with herbicides.
Soil pH (to a 15-cm depth) was 5.7 at Big Flats, 6.5 at Rock Springs, and 6.1 at Beltsville. Soil P (114–254 kg ha–1) was above optimum at each location, whereas soil K (134–260 kg ha–1) was below optimum at two sites. Potassium fertilizer (0-0-60) was applied at 40 kg K ha–1 at each location in April 2001. Nitrogen (as ammonium nitrate) was applied at 56 kg ha–1 at green-up in the spring (late March or early April) and after the second harvest each year.
Plots were harvested in April and June at Beltsville and in May and July at Big Flats in 2001 and 2002. Bottlebrush grass survival was poor at Rock Springs and the site was abandoned in spring of 2001. In 2001 and 2002, late summer and fall regrowth at each location was limited and it was decided not to take a third harvest. Bottlebrush grass accessions were at the late vegetative developmental stage at all harvests. Orchardgrass was at the inflorescence emergence stage at the first harvest and was vegetative at the second harvest. At each harvest, the number of tillers was counted on the first two experimental plants in each row. The last two experimental plants in each row were not clipped at the first harvest in each year but were monitored for anthesis date and then clipped after anthesis was reached. The same two plants were monitored each year. The remaining six experimental plants in each row were clipped to a 7-cm height, placed in cloth bags, and dried at 55°C for 48 h to determine dry matter yield per plant and for nutritive value analysis. The plot was discarded for yield purposes if fewer than four of the six plants were alive. The number of surviving experimental plants of each accession was counted in May 2003 at each location to assess persistence.
At the first harvest each year, 10 tillers of similar morphological developmental stage were taken from the experimental plants in each row. The number of leaves was counted on each tiller and the length and width of the three youngest fully elongated leaf blades were measured and leaf area calculated with a laser area meter (CID model CI-203, CID Devices Inc., Vancouver, WA). After measurements, the leaf blades and stems (including the leaf sheath) were dried at 55°C for 48 h, weighed, and the leaf-to-stem mass ratio (LSR) and specific leaf area (SLA, cm2 leaf area g–1 leaf mass) were calculated.
Forage samples from the first harvest at each location were analyzed for nutritive value via calibrated near infrared reflectance spectroscopy by the Crop Quality Laboratory at the Pennsylvania State University. Calibration samples were analyzed for neutral detergent fiber (NDF), in vitro true digestibility (IVTD; 48-h fermentation), and crude protein (CP) by a commercial laboratory (DairyOne, Ithaca, NY). Detergent fiber and IVTD procedures were according to Van Soest and Robertson (1980). Digestible NDF (dNDF) was calculated from NDF and IVTD values. Nitrogen was determined by the Dumas combustion method (AOAC, 1990) and CP calculated as N x 6.25. Calibration statistics were CP, standard error of prediction corrected for bias [SEP(C)], 7.4; R2, 0.99; NDF, SEP(C), 8.8; R2, 0.88; IVTD, SEP(C), 15.7; R2, 0.88.
The experiment was a randomized complete block design with four blocks at each location. Plot means were used in the analysis of variance. Data were analyzed and expressed on a per plant basis to simplify presentation and compensate for missing plants. Yield data were the total of two harvests in each year. A combined analysis across years and locations was done on all data. Years and locations were considered random effects and the accessions were considered fixed effects. The MIXED procedure in SAS (Littell et al., 1996) was used to perform the analysis. Denominator degrees of freedom were calculated using the Satterthwaite option of MIXED analysis to determine appropriate degrees of freedom to test fixed effects and interactions of fixed effects. Planned contrasts were used to compare means. The contrasts were (i) average of bottlebrush grass entries vs. average of orchardgrass cultivars; (ii) average of Ontario, Pennsylvania, New York, Vermont, and New Hampshire accessions vs. average of Maryland, West Virginia, and Washington, DC, accessions (northern vs. southern accessions); and (iii) average of all accessions vs. the commercial ecotype. Pearson's product moment correlations were used to determine associations between nutritive value and plant morphological traits (leaf area, length, width, SLA, and LSR). Statistical significance was declared at the P < 0.05 level.
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RESULTS AND DISCUSSION
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In Pennsylvania, bottlebrush grass performed poorly and did not survive after the first harvest in 2001. We examined several plants and found that they were infested by the bluegrass billbug, which feeds on roots and growing points. We did not observe billbug injury on bottlebrush grass at Beltsville or Big Flats. Other species of Elymus also have been identified as very susceptible to billbugs (Asay et al., 1983).
The combined statistical analysis indicated interactions among years, locations, and accessions for yield, plant morphology, and nutritive value; therefore, data are presented by year and location. Variation between years and sites was probably due to weather conditions. In 2001, rainfall for April to August was well below the long-term average at Big Flats (Table 1). Rainfall was adequate for most of the 2001 growing season at Beltsville; however, rainfall from September 2001 continuing through 2002 was much below the long-term average. In 2002, May and June rainfall was well above the long-term average at Big Flats, whereas July and August rainfall was much below average and summer temperatures were above average.
The average date of anthesis for the bottlebrush grass accessions and cultivars during the 2 yr was the second week of June at Beltsville and the first week of July at Big Flats (data not shown). Anthesis date for orchardgrass was 4 to 6 wk earlier than bottlebrush grass.
Dry Matter Yield per Plant and Persistence
Yield did not differ between the average of the northern or southern entries and the average of the accessions versus the commercial ecotype at Big Flats in both years (Table 3). The West Virginia accessions diverged widely in yield in 2002 at Big Flats and the Pennsylvania accession and commercial ecotype appeared to be much lower in yield than most other accessions in 2002. At Beltsville, the northern accessions yielded less than the southern accessions in 2002. The commercial ecotype yielded more than the average of the accessions only at Beltsville in 2001. At both locations the bottlebrush grass entries had very little regrowth in late summer and fall of 2001 and 2002. Orchardgrass yielded more dry matter per plant than bottlebrush grass at each location and in each year. Orchardgrass was included only as a frame of reference. The bottlebrush grass accessions have had no selection or breeding, whereas the orchardgrasses are proven cultivars from breeding programs.
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Table 3. Dry matter yield and survival of bottlebrush grass and orchardgrass at Big Flats, NY, and Beltsville, MD. Yield data are the sum of two harvests in each year and least squares means of four replicates. Survival data are the percentage of original plants alive in May of 2003.
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The bottlebrush grass accessions differed in persistence (Table 3). The southern accessions had better survival on average than the accessions from northern states. At Beltsville, accession 9051824 from Vermont and 9051825 from New Hampshire had the poorest survival. Overall, bottlebrush grass survival was lower than that of orchardgrass. The severe drought in 2002 coupled with sandy soil at Beltsville caused significant plant death in both bottlebrush grass and orchardgrass.
The field sites at Big Flats and Beltsville were representative of the natural habitat of bottlebrush grass, with the exception of a woodland canopy. The relatively cool, wet climate along with a deep soil with a good water holding capacity at Big Flats would seem to be conducive to bottlebrush grass growth. It did not appear, however, that bottlebrush grass persisted better at Big Flats than at Beltsville. Both experimental sites were open; perhaps performance would have been different under a woody canopy, such as in a silvopastoral system.
In a similar study, we found that Virginia wildrye also had much lower yield than orchardgrass (Sanderson et al., 2004a). Virginia wildrye averaged 42 g of dry matter per plant at Big Flats and 29 g of dry matter per plant at Beltsville for 2 yr. Survival of Virginia wildrye at Big Flats was 66 and 46% at Beltsville. Thus, bottlebrush grass was not as productive or persistent as Virginia wildrye in the northeastern USA.
Plant Morphology
Tillers per Plant
Among the bottlebrush grass entries, the southern accessions produced more tillers per plant at the first harvest each year at Beltsville and at the first harvest in 2001 at Big Flats (Table 4). With one exception (Harvest 1 in 2001 at Beltsville), orchardgrass produced more tillers per plant than bottlebrush grass.
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Table 4. Number of tillers per plant of bottlebrush grass and orchardgrass at two harvests (H1 and H2) during 2 yr at Big Flats, NY, and Beltsville, MD. Data are least squares means of four replicates.
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Bottlebrush grass seemed to have a very limited ability to maintain or activate axillary tillers after clipping. Accessions of bottlebrush grass had few tillers at Harvest 2 compared with Harvest 1, whereas orchardgrass maintained or increased tiller numbers between harvests (Table 4). It appeared that bottlebrush grass tillers tended to be synchronous in development and most tillers had elevated the growing point before harvest, whereas orchardgrass maintained more unelongated, vegetative tillers. We observed a similar tillering pattern for Virginia wildrye (Sanderson et al., 2004a). Tillers with elevated growing points must be replaced by new tillers from axillary meristems, whereas vegetative tillers continue to grow after clipping. Sometimes clipping reproductive tillers stimulates axillary tiller growth (Olson and Richards, 1988; Richards et al., 1988); however, regrowth from axillary tillers is slower than regrowth from intercalary or leaf primordial meristems (Briske, 1986).
The lack of defoliation resistance mechanisms (e.g., a prostrate growth habit, asynchronous tiller development, and compensatory physiological processes; Briske, 1986), the lack of vigorous regrowth, and the existing growth habit of bottlebrush grass and Virginia wildrye suggests that defoliation was not a selection pressure in the evolution of these accessions. Thus, developing forage types of these native grasses would require substantially altering their growth habit and tillering mechanisms.
Leaf Blade Traits
Bottlebrush grass leaf blades differed from orchardgrass in several leaf blade traits. Leaf blades of bottlebrush grass were shorter, wider, and higher in SLA than orchardgrass (Table 5). The bottlebrush grass accessions also had a greater LSR than orchardgrass. The southern accessions had longer and narrower leaves with a greater SLA than the accessions from more northern states. The LSR of the southern accessions was significantly greater at Big Flats but not at Beltsville. There were few differences between the average of the accessions and the commercial ecotype in leaf blade traits.
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Table 5. Leaf morphology of bottlebrush grass and orchardgrass at Big Flats, NY, and Beltsville, MD. Data are least squares means of four replicates and 2 yr.
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Nutritive Value
Bottlebrush grass accessions and orchardgrass differed significantly in nutritive value constituents (Table 6). On average, bottlebrush grass had greater CP, lower NDF, and greater dNDF than the orchardgrass cultivars at both Big Flats and Beltsville. This was probably because bottlebrush grass was less mature (late vegetative stage) than orchardgrass (inflorescence emergence) at harvest. The southern accessions had greater CP, lower NDF, and higher dNDF than northern accessions at Big Flats. The commercial ecotype had lower NDF and greater dNDF than the average of the accessions at Beltsville and the northern and southern accessions differed only in CP. Nutritive value constituents in Elymus and orchardgrass were greater at Beltsville than at Big Flats because of the earlier harvest date at Beltsville.
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Table 6. Nutritive value of bottlebrush grass and orchardgrass at Big Flats, NY, and Beltsville, MD. Data are least squares means of four replicates and 2 yr.
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Although the grass entries differed in nutritive value constituents, most of the variation may have been caused by differences in LSR. Concentrations of CP and dNDF were positively correlated with LSR (r = 0.64 and 0.57, respectively; P < 0.01), whereas NDF concentrations were negatively correlated (r = –0.42; P < 0.01). These correlations are consistent with results from a similar evaluation of Virginia wildrye (Sanderson et al., 2004b). Weak or inconsistent correlations occurred with leaf area, length, width, and specific leaf area (data not shown). Grass leaves generally are lower in fiber and higher in digestibility than stems, thus a greater LSR should result in greater nutritive value (Hacker and Minson, 1981). In other forage crops, such as alfalfa (Medicago sativa L.), selection for improved nutritive value altered LSR (Kephart et al., 1989).
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CONCLUSIONS
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Our results from 2 yr and three locations show that Eastern bottlebrush grass has limited potential for use as a forage grass in the northeastern USA because of its lack of defoliation tolerance, limited regrowth, and poor persistence. It may be more suited to other uses such as native grassland restoration or as part of conservation planting mixtures where defoliation does not occur. Because of its native adaptation to woodland margins, perhaps bottlebrush grass would persist and perform better in a silvopastoral system. Bottlebrush grass appears to be sensitive to drought and should not be used on soils with low water-holding capacity or where bluegrass billbug may be abundant.
Received for publication February 18, 2004.
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REFERENCES
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- Briske, D.D. 1986. Plant response to defoliation: Morphological considerations and allocation priorities. p. 425–427. In P.J. Joss et al. (ed.) Rangelands: A resource under siege. Cambridge Univ. Press, New York.
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ABSTRACT
INTRODUCTION
