Calamovilfa Longifolia Research Articles

Origin of agricultural plant pathogens: Diversity and pathogenicity of Rhizoctonia fungi associated with native prairie grasses in the Sandhills of Nebraska.

The Sandhills of Nebraska is a complex ecosystem, covering 50,000 km2 in central and western Nebraska and predominantly of virgin grassland. Grasslands are the most widespread vegetation in the U.S. and once dominated regions are currently cultivated croplands, so it stands to reason that some of the current plant pathogens of cultivated crops originated from grasslands, particularly soilborne plant pathogens. The anamorphic genus Rhizoctonia includes genetically diverse organisms that are known to be necrotrophic fungal pathogens, saprophytes, mycorrhiza of orchids, and biocontrol agents. This study aimed to evaluate the diversity of Rhizoctonia spp. on four native grasses in the Sandhills of Nebraska and determine pathogenicity to native grasses and soybean. In 2016 and 2017, a total of 84 samples were collected from 11 sites in the Sandhills, located in eight counties of Nebraska. The samples included soil and symptomatic roots from the four dominant native grasses: sand bluestem, little bluestem, prairie sandreed, and needle-and-thread. Obtained were 17 Rhizoctonia-like isolates identified, including five isolates of binucleate Rhizoctonia AG-F; two isolates each from binucleate Rhizoctonia AG-B, AG-C, and AG-K, Rhizoctonia solani AGs: AG-3, and AG-4; one isolate of binucleate Rhizoctonia AG-L, and one isolate of R. zeae. Disease severity was assessed for representative isolates of each AG in a greenhouse assay using sand bluestem, needle-and-thread, and soybean; prairie sandreed and little bluestem were unable to germinate under artificial conditions. On native grasses, all but two isolates were either mildly aggressive (causing 5-21% disease severity) or aggressive (21-35% disease severity). Among those, three isolates were cross-pathogenic on soybean, with R. solani AG-4 shown to be highly aggressive (86% disease severity). Thus, it is presumed that Rhizoctonia spp. are native to the sandhills grasslands and an emerging pathogen of crops cultivated may have survived in the soil and originate from grasslands.

Germination sensitivities to water potential among co-existing C3 and C4 grasses of cool semi-arid prairie grasslands.

An untested theory states that C4 grass seeds could germinate under lower water potentials (Ψ) than C3 grass seeds. We used hydrotime modelling to study seed water relations of C4 and C3 Canadian prairie grasses to address Ψ divergent sensitivities and germination strategies along a risk-spreading continuum of responses to limited water. C4 grasses were Bouteloua gracilis, Calamovilfa longifolia and Schizachyrium scoparium; C3 grasses were Bromus carinatus, Elymus trachycaulus, Festuca hallii and Koeleria macrantha. Hydrotime parameters were obtained after incubation of non-dormant seeds under different Ψ PEG 6000 solutions. A t-test between C3 and C4 grasses did not find statistical differences in population mean base Ψ (Ψb (50)). We found idiosyncratic responses of C4 grasses along the risk-spreading continuum. B.gracilis showed a risk-taker strategy of a species able to quickly germinate in a dry soil due to its low Ψb (50) and hydrotime (θH ). The high Ψb (50) of S.scoparium indicates it follows the risk-averse strategy so it can only germinate in wet soils. C.longifolia showed an intermediate strategy: the lowest Ψb (50) yet the highest θH . K.macrantha, a C3 grass which thrives in dry habitats, had the highest Ψb (50), suggesting a risk-averse strategy for a C3 species. Other C3 species showed intermediate germination patterns in response to Ψ relative to C4 species. Our results indicate that grasses display germination sensitivities to Ψ across the risk-spreading continuum of responses. Thus seed water relations may be poor predictors to explain differential recruitment and distribution of C3 and C4 grasses in the Canadian prairies.

Grazing Method Effect on Topographical Vegetation Characteristics and Livestock Performance in the Nebraska Sandhills

A study was conducted on upland range in the Nebraska Sandhills to determine differences in plant species frequency of occurrence and standing crop at various topographic positions on pastures grazed with short-duration grazing (SDG) and deferred-rotation grazing (DRG). Pastures within each grazing treatment were grazed at comparable stocking rates (SDG = 1.84 animal unit months (AUM) · ha−1; DRG = 1.94 AUM · ha−1) by cow–calf pairs from 1999 to 2005 and cow–calf pairs and spayed heifers from 2006 to 2008. Plant frequency of occurrence data were collected from permanently marked transects prior to, midway through, and at the conclusion of the study (1998, 2003, and 2008, respectively) and standing crop data were collected annually from 2001 to 2008 at four topographic positions (dune top, interdune, north slope, and south slope). Livestock performance data were collected during the last 3yr of the study (2006 to 2008). Positive change in frequency of occurrence of prairie sandreed (Calamovilfa longifolia [Hook.] Scribn.) was 42% greater on DRG pastures than SDG after 10yr. Total live standing crop did not differ between DRG and SDG except in 2001 when standing crop was 23% greater on DRG pastures. Standing crop of forbs and sedge was variable between grazing methods on interdune topographic positions depending on year. Average daily gain of spayed heifers (0.84± kg · d−1 SE) did not differ between SDG and DRG. Overall, SDG was not superior to a less intensively managed grazing method (i.e., DRG) in terms of vegetation characteristics and livestock performance.

Photosynthetic and morphological functional types for native species from mixed prairie in Southern Saskatchewan, Canada

Photosynthetic pathways (e.g. C3, C4) and morphological functional types (e.g. trees, shrubs, high perennial grasses, perennial forbs) were identified for the native species from the Saskatchewan mixed prairie, using the data from references published between 1950 and 2003. Of the total 219 identified species in 145 genera and 45 families, 208 species in 137 genera and 44 families were found with C3 photosynthesis, and most of these species are dominants (e.g. Agropyron dasystachyum Hook. and Stipa spartea var. curtiseta Hitchc.). 11 species in 10 genera and 3 families were identified with C4 photosynthesis (e.g. Atriplex argentea Nutt., Andropogon scoparius Michx., Boutelou gracilis Lag., Calamovilfa longifolia Hook.). The amount of total identified C4 species in the region is much less than that from the South Dakota mixed prairie (27 species). Gramineae is the leading family with C4 photosynthesis (8 species), Chenopodiaceae ranks the second (2 species). Relatively less forb types [50 % perennial forbs (PEF) and 12 % annual forbs (ANF)] and more graminoid types (25 %) composition suggested that the rangelands in the region are relatively stable. Lacking of the knowledge on the optimal traits for PFTs classification in the region, further studies (e.g. C3 and C4 plant identification and optimal trait selection) are needed to explore the relationships between PFTs and vegetation variations, as well as land-use and climate changes.

Potential utilization of native prairie grasses from western Canada as ethanol feedstock

The utilization of native grass species for potential biomass feedstocks of the emerging ethanol industry requires more information about their cellulose and hemicellulose concentration. Ten native species were grown at seven sites across the prairie region of western Canada for two to four growing seasons. Northern wheatgrass, Elymus lanceolatus, produced high concentrations of cellulose (363 g kg-1) but low concentrations of hemicellulose (266 g kg-1). Green needlegrass, Nasella viridula, produced high concentrations of both constituents (351 and 307 g kg-1). Four warm-season grasses, big bluestem, Andropogon gerardii, little bluestem, Schizachyrium scoparium, prairie sandreed, Calamovilfa longifolia, and switchgrass, Panicum virgatum, had 346, 342, 340 and 338 g kg-1, respectively, concentrations of cellulose and also exhibited a positive response to temperature that resulted in increased hemicellulose concentration. Accumulated thermal time (degree day base 10°C) was correlated to hemicellulose concentrations in the warm-season grasses but not for cool-season grasses. Holocellulose (cellulose + hemicellulose) concentration differences varied among site-years but warm-season grasses were more stable in hollocellulose concentration than cool-season grasses. Key words: Biomass, native grasses, cellulose, hemicellulose, biofuel

Base Temperatures for Seedling Growth and Their Correlation with Chilling Sensitivity for Warm‐Season Grasses

Initial screening of warm‐season grasses for cultivation in cool, short season growing areas has been focused on frost and chilling tolerance. Adoption of warm‐season grasses in these areas has resulted in an increase in degree‐day modeling of their growth. These predictive models are dependent on accurate determination of the basal temperatures for growth. In this study, base temperatures for seedling growth were estimated for switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), Indian grass (Sorghastrum nutans L. Nash), and prairie sandreed [Calamovilfa longifolia (Hook) Scribn.]. Seedlings at the two‐leaf stage were grown at 4, 8, 12, 16, and 24°C in growth chambers for 4 wk with representative harvests every week. Relative growth rates were calculated for each species at each temperature and these were used, in conjunction with regression techniques, to estimate base temperatures for growth. The base temperatures were then correlated with chilling sensitivity of the plants, estimated using visual scores, chlorophyll fluorescence, and electrolyte leakage. The estimated base temperatures ranged from 2.6 to 7.3°C. There were variations among and within species in base temperatures for seedling growth. There were positive correlations between base temperatures for growth and rate of electrolyte leakage (r = 0.73), chlorophyll fluorescence (FV/FM; r = 0.80) and leaf damage (visual score; r = 0.76). These correlations confirm the differences in adaptation of warm‐season grasses, both within and across species. They also support the differences in base temperatures. This highlights the need to use different base temperatures in statistical growth models for different species or cultivars.

Base Temperatures for Seedling Growth and Their Correlation with Chilling Sensitivity for Warm-Season Grasses

Initial screening of warm-season grasses for cultivation in cool, short season growing areas has been focused on frost and chilling tolerance. Adoption of warm-season grasses in these areas has resulted in an increase in degree-day modeling of their growth. These predictive models are dependent on accurate determination of the basal temperatures for growth. In this study, base temperatures for seedling growth were estimated for switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), Indian grass (Sorghastrum nutans L. Nash), and prairie sandreed [Calamovilfa longifolia (Hook) Scribn.]. Seedlings at the two-leaf stage were grown at 4, 8, 12, 16, and 24°C in growth chambers for 4 wk with representative harvests every week. Relative growth rates were calculated for each species at each temperature and these were used, in conjunction with regression techniques, to estimate base temperatures for growth. The base temperatures were then correlated with chilling sensitivity of the plants, estimated using visual scores, chlorophyll fluorescence, and electrolyte leakage. The estimated base temperatures ranged from 2.6 to 7.3°C. There were variations among and within species in base temperatures for seedling growth. There were positive correlations between base temperatures for growth and rate of electrolyte leakage (r = 0.73), chlorophyll fluorescence (FV/FM; r = 0.80) and leaf damage (visual score; r = 0.76). These correlations confirm the differences in adaptation of warm-season grasses, both within and across species. They also support the differences in base temperatures. This highlights the need to use different base temperatures in statistical growth models for different species or cultivars.

Stomatal variability of native warm-season grasses from the Nebraska Sandhills

Soil moisture deficit is usually the major limiting factor for herbage production in the Sandhills of Nebraska. We examined inter-population and interspecific variability in stomatal characteristics and drought tolerance in sand bluestem (Andropogon hallii Vitman), little bluestem [Schizachyrium scoparium (Michx.) Nash], prairie sandreed [Calamovilfa longifolia (Hook) Scribn.], and switchgrass (Panicum virgatum L.). Ramets were collected during the dormant season across an aridity gradient from east to west (ranging from 560 mm to 340 mm average annual precipitation) in the Sandhills of Nebraska. Plants were grown in individual pots under greenhouse conditions. Once plants were well established, stomatal characteristics were determined and stomatal conductance (gs) was measured through a dry-down period of no watering. Populations did not differ in stomatal characteristics across the gradient, except for stomatal density on the adaxial leaf surface of prairie sandreed and the abaxial leaf surface of sand bluestem. Leaves of switchgrass and prairie sandreed were amphistomatic (stomata on both leaf surfaces), whereas leaves of little bluestem and sand bluestem were hypostomatic (stomata on the lower leaf surface). In the absence of drought, gs was 17 to 31% higher in little bluestem than in other species. Differences among species in gs were found mainly when watered and disappeared as the dry-down progressed. There was a positive relationship between stomatal density and gs in all species except prairie sandreed. Prairie sandreed maintained 35% of the initial relative water content of its leaves after 17 d of dry-down, compared to 23% for sand bluestem, 14% for switchgrass, and 9% for little bluestem. Variation in stomatal traits within species did not explain ecotypic adaptation to sites with a range of precipitation in the Nebraska Sandhills. Key words: Stomatal characteristics, water stress, warm season grasses, Nebraska Sandhills

Seasonal Dynamics of Prairie Sandreed Rhizome Development

Multiple generations of rhizome-connected tillers stabilize soils and produce measurable amounts of herbage on sandy rangeland throughout the world. However, little is known about the dynamics of rhizome development in these clonal plant species. Seasonal relationships between foliar characteristics and rhizomes of prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] were examined on sands range sites at 30-day intervals from May through September 1989 and 1990 at the University of Nebraska, Panhandle Experimental Range near Scottsbluff. Quadrats were excavated each year from two, 5 x 5 Latin Square macroplots in each of 2 grazing histories, long-term rest or current-year deferment. Under dry conditions in 1989, a 65% reduction in the length of new rhizomes during July preceded a 64% reduction in live tillers in August. After which, rhizome length and live tiller density were unchanged and mean tiller weight increased during September. When average precipitation occurred in 1990, a 25% reduction in live tillers and concurrent increases in new rhizome length and mean tiller weight occurred during July. Rhizome bud densities increased throughout the growing season at different but predictable rates (R2 greater than or equal to 0.95) for grazing histories, regardless of precipitation. Length of new rhizomes was highly correlated (R2 = 0.91) with live herbage throughout the growing season. Measurable increases in total rhizome length did not occur until live herbage of prairie sandreed exceeded a threshold of about 50 g m(-2). Maximum increase in length of new rhizomes per unit of live herbage was about 10 cm g(-1) near 100 g m(-2). Given its dependence on vegetative reproduction and relatively high palatability to beef cattle, periodic or repeated years of full growing season deferment may be the only reliable method of obtaining measurable increases in prairie sandreed populations. DOI:10.2458/azu_jrm_v55i2_reece

Seasonal dynamics of prairie sandreed rhizome development

Multiple generations of rhizome-connected tillers stabilize soils and produce measurable amounts of herbage on sandy rangeland throughout the world. However, little is known about the dynamics of rhizome development in these clonal plant species. Seasonal relationships between foliar characteristics and rhizomes of prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] were examined on sands range sites at 30-day intervals from May through September 1989 and 1990 at the University of Nebraska, Panhandle Experimental Range near Scottsbluff. Quadrats were excavated each year from two, 5 x 5 Latin Square macroplots in each of 2 grazing histories, long-term rest or current-year deferment. Under dry conditions in 1989, a 65% reduction in the length of new rhizomes during July preceded a 64% reduction in live tillers in August. After which, rhizome length and live tiller density were unchanged and mean tiller weight increased during September. When average precipitation occurred in 1990, a 25% reduction in live tillers and concurrent increases in new rhizome length and mean tiller weight occurred during July. Rhizome bud densities increased throughout the growing season at different but predictable rates (R2 greater than or equal to 0.95) for grazing histories, regardless of precipitation. Length of new rhizomes was highly correlated (R2 = 0.91) with live herbage throughout the growing season. Measurable increases in total rhizome length did not occur until live herbage of prairie sandreed exceeded a threshold of about 50 g m(-2). Maximum increase in length of new rhizomes per unit of live herbage was about 10 cm g(-1) near 100 g m(-2). Given its dependence on vegetative reproduction and relatively high palatability to beef cattle, periodic or repeated years of full growing season deferment may be the only reliable method of obtaining measurable increases in prairie sandreed populations.

Tiller Recruitment Patterns and Biennial Tiller Production in Prairie Sandreed

Tiller recruitment is an essential process for ensuring the perenniality of grasses. The timing and extent of tiller recruitment and the role of biennial tillers must be documented for key range species. Prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] is an important grass in the Nebraska Sandhills for both ecological functioning and as a forage. The objective of this study was to document tiller recruitment patterns and the occurrence and contribution of current year and biennial tillers to biomass production in prairie sandreed at 2 locations in Nebraska. Tiller recruitment was monitored at 2-week periods throughout the growing season during a 2-year period. Newly emerged tillers were classified as intravaginal, extravaginal, or rhizomatous tillers and marked with colored wire. Prairie sandreed has an unimodal pattern of tiller recruitment and over 50% of the current year tillers emerged by mid-May and 80% by mid-June. Rate of tiller emergence and absolute number of emerged tillers were poorly correlated with short- and long-term precipitation totals (r 0.20). The year after new tillers were marked, biennial tillers and tillers initiated during the current-year were counted and clipped in September for biomass determination Biennial tillers made up only 6 and 20% of the total tiller emergence at these locations and were generally only 30% as large as the new tillers. Extravaginal tillers composed over 78% of the biennial tiller population as a result of both their dominance in emerging populations and the higher percentage of tillers that survived the winter. Current year tillers contributed the most to prairie sandreed forage production and their emergence was largely completed by mid-June. The lack of a relationship between tiller recruitment and precipitation patterns, combined with previous studies of prairie sandreed, indicates that tiller recruitment involves a process that begins the previous growing season. DOI:10.2458/azu_jrm_v53i5_hendrickson

Tiller recruitment patterns and biennial tiller production in prairie sandreed

Tiller recruitment is an essential process for ensuring the perenniality of grasses. The timing and extent of tiller recruitment and the role of biennial tillers must be documented for key range species. Prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] is an important grass in the Nebraska Sandhills for both ecological functioning and as a forage. The objective of this study was to document tiller recruitment patterns and the occurrence and contribution of current year and biennial tillers to biomass production in prairie sandreed at 2 locations in Nebraska. Tiller recruitment was monitored at 2-week periods throughout the growing season during a 2-year period. Newly emerged tillers were classified as intravaginal, extravaginal, or rhizomatous tillers and marked with colored wire. Prairie sandreed has an unimodal pattern of tiller recruitment and over 50% of the current year tillers emerged by mid-May and 80% by mid-June. Rate of tiller emergence and absolute number of emerged tillers were poorly correlated with short- and long-term precipitation totals (r < 0.3 P > 0.20). The year after new tillers were marked, biennial tillers and tillers initiated during the current-year were counted and clipped in September for biomass determination Biennial tillers made up only 6 and 20% of the total tiller emergence at these locations and were generally only 30% as large as the new tillers. Extravaginal tillers composed over 78% of the biennial tiller population as a result of both their dominance in emerging populations and the higher percentage of tillers that survived the winter. Current year tillers contributed the most to prairie sandreed forage production and their emergence was largely completed by mid-June. The lack of a relationship between tiller recruitment and precipitation patterns, combined with previous studies of prairie sandreed, indicates that tiller recruitment involves a process that begins the previous growing season.

Early Summer Grazing Effects on Defoliation and Tiller Demography of Prairie Sandreed

Grazing strategies should be designed to maintain vigorous populations of plant species critical for livestock production, wildlife habitat, and/or ecosystem functions. Treatments consisting of 5- to 7-day, mid-month grazing periods in June or July at 16, 32, or 48 animal unit days (AUD) per ha, were replicated 3 times and applied to the same pastures in 1995 and 1996 to quantify cattle use and tiller recruitment and mortality of prairie sandreed [Calamovilfa longifolia (Hook) Scribn.], a rhizomatous species characterized by dispersed populations of tillers. Cumulative grazing pressure (AUD Mg -1 ) was used to quantify treatments because of differences in phytomass among pastures and dates. Grazing pressure ranged from 10 to 90 AUD Mg -1 and accounted for 69, 61, and 77% of the variation in percentage of tillers grazed, mean defoliation of grazed tillers, and use of prairie sandreed, respectively. As grazing pressure increased from 10 AUD Mg -1 , percentage of tillers grazed increased from 48 to 90%; defoliation of grazed tillers increased from 54 to 74%; and utilization of prairie sandreed increased from 27 to 67% at plateaus beginning at 50 to 60 AUD Mg -1 . When spring precipitation was above average, 45 to 55% use in June or July increased tiller densities, however, these increases were not sustained or repeated in the following year with average precipitation. Utilization was 50% at 28 AUD Mg -1 and 60% at 40 AUD Mg -1 . Relatively large increases in utilization per-unit-change of grazing pressure below 20 AUD Mg -1 indicated that yearling cattle selectively grazed prairie sandreed. The high degree of correlation between percentage of prairie sandreed tillers grazed and use of prairie sandreed (R 2 = 0.91 in June and 0.90 in July) suggests that percentage of grazed tillers can be used to monitor early-summer use of this species in the Nebraska Sandhills.

Late-Summer Forage on Prairie Sandreed Dominated Range-Land after Spring Defoliation

The potential of using spring defoliation to improve late-summer nutritive value of prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.] on rangeland was studied with a factorial array of replicated 1-year treatments that included clipping plots at ground level or at a 5 or 10 cm height on 1 April, 26 April, 20 May, or 14 June. Vegetative tillers accounted for 83% of prairie sandreed herbage on unclipped control plots. After spring treatments, late-summer crude protein content (CP) in vegetative tillers of prairie sandreed ranged from 5.0 to 7.9% and in vitro dry matter digestibility (IVDMD) ranged from 45 to 52% compared to 5.0% CP and 45% IVDMD for unclipped plots. Reductions in mean weight of prairie sandreed vegetative tillers after April and May treatments were offset by 20 to 30% increases in tiller density. Treatments that increased tiller density had little or no effect on forage nutritive value when applied more than 90 days before herbage was sampled. Nutritive value of prairie sandreed and total yield from all species in mid-September were unchanged after April treatments. After sandreed tillers began to emerge in early May, late-summer nutritive value improved as clipping was delayed and degree of defoliation increased during May and June, however, yield was inversely related to nutritive value. While mid-September nutritive value of prairie sandreed was comparable to mid-summer values after June treatments, clipping reduced projected, late-summer stocking rates by 58 to 100% compared to control. It may be possible to improve mid-September forage nutritive value with moderate stocking rates in June with less reduction of total late-summer herbage because of selective herbivory. Measurable increases in prairie sandreed yield after complete defoliation of associated species in late April indicated prairie sandreed populations might be increased by concentrating cattle in selected pastures during late April.

Kraft pulping characteristics and pulp properties of warm season grasses

Non-wood fibres are increasingly being used in the pulp and paper industry to help meet the increasing world demand for paper. Their use also helps to reduce demand on declining forest reserves. In this study several warm season grasses, prairie sandreed ( Calmovilfa longifolia (Hook.) Scribn.), cordgrass ( Spartina pectinata L.), big bluestem ( Andropogon gerardii Vitman), and switchgrass ( Panicum virgatum L. cv. Pathfinder (PF) and New Jersey 50 (NJ50)), were evaluated as potential raw materials for pulp and paper production. Raw material chemical composition, kraft pulp yield and properties, and fibre characteristics were evaluated. All these grasses were easily pulped under a mild kraft process, with pulp yields ranging from 44 to 51%, highest yields were recorded for NJ50 and big bluestem; and kappa numbers ranging from 10 to 16. The weight-weighted fibre length ranged from 1.29 to 1.43 mm, the highest value being recorded for big bluestem. The unbeaten pulp freeness ranged from 275 ml for sandreed to 411 ml for NJ50. Sandreed, NJ50 and big bluestem had high tear indices of 7.49, 7.12 and 7.07 mN m 2 g −1, respectively. Cordgrass and sandreed had burst indices above 5.0 kPa m 2 g −1 (5.68 and 5.22 kPa m 2 g −1, respectively). Other physical and strength properties are also presented.

Technical Note: A Rotary Seed Processor for Removing Pubescence from Seed of Prairie Grasses

Many of the perennial prairie grasses that are used in restoration plantings in the central Great Plains have seed appendages such as awns and pubescence that make seed now through planters difficult. We have developed a rotary seed processor that efficiently processes small breeder or experimental lots of seed that can then be easily planted with small plot cone planters or conventional planters. The processor consists of a metal cylinder that is lined with corrugated rubber and a rotating center shaft with rubber paddles. Processing can be controlled by varying shaft rotation speed and processing time. A top-opening, full length trap door allows for easy loading and the cylinder can be inverted to dump out processed seed. The processor has been used successfully for several years on big bluestem [Andropogon gerardii Vitman], indiangrass [Sorghastrum nutans (L) Nash], little bluestem [Schizachyrium scoparium (Michaux) Nash], prairie sand reed [Calamovilfa longifolia (Rook.) Scribner] , and blue grama [Bouteloua gracilis (Willd. ex Kunth) Lagascaex Griffiths] seed. By removing seed appendages and pubescence, seed bulk is reduced and seed density and flow ability are improved. The processing operation is relatively gentle and seed germination per unit weight of seed is improved.

Evaluation of selected warm-season grasses for biomass production in areas with a short growing season

Field studies were conducted in 1994 and 1995 to determine the phenology, leaf and tiller characteristics and yield of 22 warm-season grasses in south western Quebec, Canada. Cordgrass ( Spartina pectinata L.), two cultivars of Indiangrass [ Sorghastrum nutans L. (Nash)], two cultivars of big bluestem ( Andropogon gerardii Vitman), 12 cultivars of switchgrass ( Panicum virgatum L.) and five cultivars of prairie sandreed [ Calamovilfa longifolia (Hook) Scribn., were included in the study. In terms of initial spring growth, CWNC (cordgrass) and New Jersey 50 (switchgrass) were the earliest and latest, respectively. Initial spring regrowth from sandreeds was predominantly from continued growth of biennial tillers, from rhizomes in cordgrass and from buds on stem bases for the other species. The earliest maturing entries were ND3743, Dakota, Ottawa3 (switchgrasses) and Bison (big bluestem). New Jersey 50 and CWNC were the latest maturing. CWNC had high tiller numbers throughout the season while the rest of the entries showed increases in tiller numbers in summer. There were significant differences among entries in height development across the season. Biomass yields ranged from 65 to 861 g per plant. Lignocellulose concentration was high in all entries with neutral detergent fiber (NDF) and acid detergent fiber (ADF) ranging from 770–860 g kg −1 and 460–540 g kg −1, respectively. Nitrogen and ash concentrations ranged from 4–10 and 40–70 g kg −1, respectively. The results indicate potential for cordgrass (CWNC) and several switchgrasses for biomass production in the short season areas of Quebec.

Soil Aggregation and Organic Matter Mineralization in Forests and Grasslands: Plant Species Effects

AbstractPlant‐soil feedbacks can alter N cycling rates in terrestrial ecosystems, but the mechanistic relationship between species characteristics, soil properties, and N dynamics is unclear. Plant species may affect patterns of soil aggregation, which can affect soil C and net N mineralization. This mechanism was examined in two common garden experiments: one containing five tree species (European larch [Larix decidua Miller], red oak [Quercus rubra L.], red pine [Pinus resinosa Ait.], white pine [Pinus strobus L.], and Norway spruce [Picea abies (L.) Karst]) and one containing six grass species (big bluestem [Andropogon gerardi Vitm.], indiangrass [Sorghastrum nutans (L.) Nash], prairie sandreed [Calamovilfa longifolia (Hook) Scrib.], switchgrass [Panicum virgatum L.], little bluestem [Schizachyrium scoparium (Michx.) Nash.], and sideoats grama [Bouteloua curtipendula (Michx.) Torr.]). The grass monocultures are burned annually. Soils were wet sieved into four size classes (>2000, 250‐2000, 53‐250, and <53 µm). Unsieved soil was incubated aerobically for 30 and 387 d to examine C and net N mineralization. For tree species, aggregate weighted mean diameter (WMD) differed between species (P = 0.01), and correlated positively with fungal biomass (r = 0.56). Large macroaggregate (>2000 µm) C concentration ranged from 15 to 26 g kg‐1, and was lowest for Norway spruce and red oak (P = 0.07). Aggregate WMD correlated weakly (and negatively) with potentially mineralizable N (r = −0.57) and in situ net N mineralization (r = −0.67), but positively (again weakly) with potentially mineralizable C (r = 0.49). Grass species had no effect on aggregate‐size distribution or organic matter concentration in spite of twofold differences in root biomass and threefold differences in N cycling rates. Species‐induced changes in soil aggregation explained little of the variation in whole‐soil C and N cycling rates, and are therefore unlikely to be an important mechanism explaining species effects on ecosystem processes.

Morphological Development of 2 Warm-Season Grasses in the Nebraska Sandhills

Morphological development of grasses has numerous implications to rangeland management including the timing and amount of herbivory. The objective of this study was to quantify the developmental morphology of prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.] and sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern.] tiller populations. Tiller populations of these 2 grasses were studied for 2 years in the Nebraska Sandhills. Plant development was evaluated using a growth staging system which quantifies the development of tiller populations. A morphological growth index for each species was calculated from either the weighted average of tiller numbers reported as mean stage count (MSC) or tiller weight reported as mean stage weight (MSW) and correlated with the independent variables of growing degree days (GDD) and day of year (DOY). Correlation coefficients with the independent variables were greater than 0.97 for MSC and MSW within years and greater than 0.90 between years. Greater rainfall and warmer temperatures in 1991 increased the number of tillers in the more advanced morphological stages in prairie sandreed, but tiller weight rather than tiller number increased in more advanced stages of sand bluestem. A majority of the harvested tillers were vegetative throughout the sampling period but by the end of the growing season, a wide range of morphological stages were present. The use of grazing to prevent the formation of culmed tillers in these grasses may be unnecessary because of the high proportion of vegetative tillers and the wide range of morphological stages available for selection by livestock.

Relationships between Physical and Chemical Characteristics of 3 Sandhills Grasses

Physical and chemical traits of grass tillers can be strongly correlated. Understanding such patterns would help define physiological development of tillers and changes in quality of forage in Sandhills grasses. Physical and chemical traits were quantified for sand bluestem (Andropogon hallii Hack.), prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.], and little bluestem [Andropogon scoparius (Michx.)] on 3 sites at 4 times (mid-June, July, August, and October) during the 1990 and 1991 growing seasons. Thirty tillers were identified along two, 50-m transects (30 tillers/species/transect) within each site and tiller growth stage, length, and erectness determined. Tiller weight was defined from plants collected within 20 quadrats/site. Protein content, in vitro dry-matter digestibility (IVDMD), hemicellulose, total cell wall, acid detergent fiber (ADF), lignin, ash, total chlorophyll, and nonstructural carbohydrates (TNC) were determined on plant materials representing the dominant growth stages. Relationships among traits of the 3 species were determined by Spearman's rank correlation, and among linear combinations of sets of chemical and physical traits by canonical correlation analysis. Tiller length, weight, and growth stage were positively correlated (P < 0.05) and increased with length of growing season. Crude protein, digestibility, hemicellulose and chlorophyll were positively correlated and declined, but negatively correlated with lignin and ash. Significant (P < 0.05) correlations between the first canonical variates indicated a strong relationship between tiller maturity/architectural development (physical canonical variate) and forage quality (chemical canonical variate) was present, and large portions of variance in the original variables was defined. Results of this study defined large-scale multi-dimensional relationships between declining forage quality and increasing tiller maturity/architectural development, previously noted in many univariate analyses of limited sets of characteristics.