Introduction

Rangeland wildfires are becoming increasingly frequent and widespread worldwide (Pechony and Shindell 2010). Wildfire control and post-fire rehabilitation of rangelands in the semi-arid western U.S. has received considerable attention (Clements et al. 2009) given the substantial economic and environmental costs of wildfires (Dunn 2003; Mackes et al. 2007). Various plant species and landscape or “greenstripping” patterns have been proffered for use in modifying fire escalation and behavior (Finney 2001, Finney et al. 2007; Manzello et al. 2006). Plant species that enhance ecological function, possess salinity, drought, and heat tolerance, and remain green throughout the summer are particularly amenable for use in greenstripping on western U.S. rangelands (Monsen 1994; Pellant 1994).

The large and genetically variable genus Festuca of the Poaceae family houses approximately 450 grass species in nine subgenera that are found worldwide from tropical to alpine environments (Clayton and Renvoize 1986). The Festuca subgenus Festuca is the largest of these subgenera and contains the economically-important turfgrasses known as “fine fescues”, which are characterized by their fine and very narrow (less than 1 mm) leaves (Beard, 1973). Fine fescues can be subdivided into two botanical complexes (aggregates), Rubra and Ovina, which are often cytologically difficult to differentiate (Vinall and Hein 1937; Pavlick 1984). The Rubra complex species are rhizomatous, morphologically diverse, polyploid, and outcrossing. Historically, this complex has consisted of F. heterophylla Lamarck and three F. rubra subspecies [subsp. commutata (Thuill.) Nyman, subsp. litoralis (G.F.W. Meyer) Auquier, and subsp. rubra Gaudin] (Darbyshire and Pavlick 2007; Ruemmele et al. 2003), while other F. rubra subspecies have more recently been cited by St. John et al. (2012). The Ovina complex includes seven non-creeping species, F. ovina L. (sheep fescue; 2x), F. valesiaca Schleich. ex Gaudin (Volga fescue; 2x–10x), F. filiformis Pourr. (hair fescue; 2x), F. idahoensis Elmer (Idaho fescue; 4x), F. roemeri (Pavlick) E. B. Alexeev (Roemer’s fescue; 4x–6x), F. trachyphylla (hard fescue; 6x), and F. viviparoidea Krajina ex Pavlick subsp. viviparoidea (viviparous fescue; 4x–6x) (Pavlick 1984; Darbyshire and Warwick 1992; Arndt 2008).

Fine-leaved Festuca grass species can possess drought and shade tolerance and adaptation to infertile acid soils (pH 5.5–6.5) in cool-humid and semi-arid regions, but are not necessarily heat tolerant (Hanson 1972; Hanson et al. 1969; Beard, 1973; Ruemmele et al. 1995). They are often considered for low maintenance turf applications (cultured and roadside) and establishment of pastures in poorly drained soils, yet respond well to nitrogen fertilization (Beard 1973; Meyer and Funk 1989). Given their inherent tolerance to abiotic stresses (Ruemmele et al. 1995), they may have potential for use in greenstripping in the western US.

Collection of fine fescue grasses from areas of origin has provided genetic resources needed for targeted germplasm enhancement (Ruemmele et al. 2003). Thus, in 2006, two multi-national plant expeditions collected eight fine-leafed F. rubra L. accessions from fire prone, heavily grazed semi-arid rangelands of Kyrgyzstan (KGZ) and the People’s Republic of China (CHN) (Johnson 2006a, b). These KGZ (4) and CHN (4) F. rubra (2n = 6x–8x) collections were evaluated herein to determine their genetic relatedness and agronomic potential for use in semi-arid western US rangelands. The morphology of these F. rubra collections were initially compared to eight commercial cultivars (2n = 2x, 6x, 8x), and four previously described KGZ F. valesiaca (2x) plant introductions (Ma et al. 2014) at a single-location, multi-year field trial (Experiment 1) in a high desert region of the U.S. Great Basin (~1400 m elevation). The genetic relatedness of these accessions and commercial cultivars was also evaluated using amplified fragment length polymorphism (AFLP) markers. Four accessions that represented the range of morphological variation present in Experiment 1 were then further evaluated in a second trial (Experiment 2) to assess their performance in three geographically diverse high desert locations over 2 years. If agronomic potential exists among these F. rubra collections, then breeding for drought/heat tolerant, erect, late flowering, wildfire resilient genotypes adapted to western U.S. growing conditions could result in plant types for rangeland applications (e.g., greenstrips and restoration) in Great Basin desert regions.

Materials and methods

Germplasm

We use herein the general taxonomic treatment of Catalán et al. (2004) and that of Barkworth et al. (2007) because of their historical context to North American flora and their recognition of worldwide Festuca species that have been introduced to the North American continent. However, Markgraf-Dannenberg’s treatment of the Flora of Turkey indicates that F. ovina L. does not exist in Turkey (Markgraf-Dannenberg 1980) and perhaps not in the Middle-East (Wilkinson and Stace 1991). Therefore, we classified the F. ovina accessions with Middle-Eastern or Asian origins received from the U.S. Department of Agriculture, Agricultural Research Service, Plant Genetic Resources Unit as identified in its Genetics Resources Information Network (GRIN; http://www.ars-grin.gov) as F. valesiaca according to Arndt (2008).

The seven Festuca species evaluated (20 entries total) for morphology and DNA genotyping in Experiment 1 were obtained from commercial [Granite Seed Co., Lehi, UT (GSC)] and public [U.S. National Plant Germplasm System (GRIN) and Utah State University (USU)] sources (Table 1). The commercial Festuca species checks and the F. valesiaca and F. rubra accessions examined were chosen based on their known or putative taxonomic relationships with F. rubra and collection site similarities. The commercial cultivars Manhattan 4 (Lolium perenne L.), Coronado [Schedonorus arundinaceus (Schreb.) Dumort. (syn. Festuca arundinacea Schreb.), nom. cons.], Black sheep (F. ovina L.), Cascade [F. rubra L. subsp. commutata (Gaudin) Markgr.-Dann.], Dawson E (F. rubra L. var. littoralis Vasey ex Beal; syn. F. rubra L. subsp. densiuscula Hack. ex Piper), Shademaster (F. rubra L. subsp. rubra), Durar [F. trachyphylla (Hack.) Krajina; synom. F. lemanii T. Bastard], and Scaldis (F. trachyphylla) were used as checks. Festuca rubra plant introductions (PI) were collected from overgrazed arid sites in 2006 near Naryn (41°43′59′′N 75°27′2′′E; PI 659946), Ysyk-Kol (42°10′58′′N 78°0′28′′E; PI 659899), and Chuy (42°11′34″N 73°45′22″E; PI 659950, PI 659954) KGZ, and Qinghai (35°N 96°E; PI 659984) and Inner Mongolia (Nei Mongol Autonomous Region near Xilinhot City, 43°54’60″N 115°57′30″E; PI 659965, PI 659966, and PI 659981) CHN (Johnson 2006a, b). The F. valesiaca accessions were chosen based on their superior performance for agronomic traits (Ma et al. 2014) and originate from the same regions in Kyrgyzstan [Naryn (PI 659923 and PI 659932) and Chuy (PI 670362 and PI 670364)]. For Experiment 2 (multiple locations), four F. rubra accessions demonstrating poor (PIs 659966 and 659981), average (PI 659965), and superior (PI 659984) performance in Experiment 1 were evaluated with four commercial check cultivars [Black Sheep, Shademaster, Durar, and Covar (F. valesiaca subsp. valesiaca)] and four F. valesiaca or F. valesiaca × F. ovina hybrids (R4S4, R4S6, R4S22, and R4S32; Table 1) developed at the Forage and Range Research Laboratory (FRRL) that were the best performing hybrid entries in a previous multi-location Festuca field trial (Robbins et al. 2016).

Table 1 Plant material evaluated in two experiments (Expts. 1 and 2) in Blue Creek, UT from 2008 to 2011 (Expt. 1) and in Malta, ID, Blue Creek, UT, and North Logan, UT from 2011 to 2013 (Expt. 2)
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Morphological evaluation

Experiment 1 In January 2008, seeds of each accession were germinated on blotter paper, and then seedlings were established and maintained in a greenhouse in Logan, UT under environmental conditions according to Ma et al. (2014). Seedlings of each accession were transplanted in May 2008 to a field nursery at the Utah State University Blue Creek Experimental Farm in Box Elder County, UT (41°56′3.14′′N 112°26′20.01′′W, elevation = 1433 m) approximately 80 km northwest of Logan, UT, where the average annual precipitation during this experiment (2009–2011) was 388 mm (average 20-year precipitation = 307 mm) (PRISM 2015). The soil type was a Parley’s deep silt loam (fine-silty, mixed, mesic, Calcic, Argrixerolls) having a neutral to slightly acidic pH (http://websoilsurvey.nrcs.usda.gov/). Plants were arranged in a randomized complete block design (RCBD) with five plants per plot in six replications spaced at 0.5 m within the rows and 1 m between rows (~20,000 plants/ha) with plants of PI 659984 (F. rubra; Qinghai, China) used as end- and side-borders. Although plants were given water at transplanting, no water or fertilizer was applied during the experiment, and weeds were controlled by hand and with a broadleaf herbicide (MEC Amine-D) according to Ma et al. (2014).

Phenotypic evaluation of all entries for above ground biomass, persistence, number of seeds per plant (evaluated 2009–2011), plant vigor, height, and width (2010–2011) were measured. Plant vigor was assessed by plot in early June using an 11-point visual rating scale from 0 to 5 (0.5 as units), where 0 = plant dead, 3 = moderate biomass with green foliage, and 5 = rich green plants with abundant biomass. Plant height (cm) and width (cm) was measured in early-middle July on each plant as the distance from the plant base (soil surface) to the top of the highest panicle at full anthesis and the diameter of the tussock ~10 cm above ground, respectively. For biomass, leaves and seed stalks were harvested ~10 cm above ground at seed maturity in late July and oven dried at 60 °C to measure above ground dry weight (g). Persistence was calculated as the number of plants alive at biomass harvest in each plot divided by the number of plants transplanted at the beginning of the experiment. The number of seeds per plant was determined by weighing the seeds of each plant (mechanically separated from chaff) and converting seed weight to seed number using the weight of one hundred seeds from at least three replicates for each entry.

Experiment 2 Seeds of each entry evaluated were germinated and seedlings were established and maintained as described above. Greenhouse established seedlings were transplanted in May 2011 to field nurseries at North Logan, Cache County, UT (41°47′9.27″N 111°48′51.76″W; elevation = 1392 m), Blue Creek, UT (site of Experiment 1), and at the University of Idaho L. A. Sharps Experimental Station (42°18′5.90″N 113°11′49.51″W, elevation = 1476 m) near Malta, ID approximately 176 km northwest of Logan, UT. The soil type at North Logan and Malta was a McMurdie silt loam, and a Declo silt loam, respectively (http://websoilsurvey.nrcs.usda.gov/). The average annual precipitation during the experiment (2011–2013) at North Logan, Blue Creek, and Malta was 440, 362, and 265 mm, respectively, while the 30-year averages at these locations were 484, 407, and 291 mm, respectively (PRISM 2015). Plants were arranged in an RCBD with ten (North Logan and Malta) or five (Blue Creek) plants per plot in six replications, with the same spacing and borders as in Experiment 1. No supplemental water or fertilizer was applied to plants at planting, during establishment, or at any point during the experiment and weeds were controlled as in Experiment 1.

All entries were evaluated for plant vigor, the number of seeds per plant, and persistence using methods for Experiment 1 above, and early and late biomass and early and late regrowth. Leaves and seed stalks of the first half of each plot (the first 5 plants of the plot in North Logan and Malta and the first 3 plants in Blue Creek) were harvested just before anthesis and oven dried at 60 °C to measure dry weight (g) for early biomass. The second half of the plot was similarly harvested when seeds were mature as a second, late-season measure of biomass (~30 days after the initial biomass harvest) and to estimate seed yield. Regrowth (leaf and stem growth from the first harvest to the end of the growing season in late September or early October) was harvested separately on plants from the early biomass and later biomass/seed harvests in each plot at the same height as the original harvest. Since not all entries in Experiment 1 were evaluated in Experiment 2 (i.e., ‘Covar’, R4S4, R4S6, R4S22, and R4S32), the weight of 100 seeds was not available for these entries. Therefore, for all entries in Experiment 2, seed number per plant was estimated from seed weights using the average value of 0.0574 g per 100 seeds from Experiment 1. Data for the second biomass, seed yield, and regrowth were not available for the Malta location in 2013 due to significant rabbit (Lepus californicus deserticola means) predation throughout the trial after the first biomass harvest.

Phenotypic trait analysis

Phenotypic data from both Experiments 1 and 2 were analyzed following the procedures outlined in Robbins et al. (2016). Briefly, trait data were analyzed separately for each experiment on per-plot means using a linear mixed models analysis. Residuals for all traits were tested for normality and homogeneity of variance, and the only data that required transformation were measurements of regrowth data at the late harvest. Although a natural log transformation improved normality (data not presented), the results are reported herein in their original scale (i.e., analyzed untransformed) for biological relevance and interpretation.

The main effects of year, location, and entry as well as the interaction effects of year by location, year by entry, location by entry, and year by location by entry were tested using a repeated measures model with compound symmetry covariance structure using year as the repeated factor and each plot as the subject with year, location, and entry as fixed effects and replication as a random effect (Robbins et al. 2016; Smith and Casler 2004). Due to missing data from rabbit predation (Malta), data for the second biomass, seed yield, and regrowth were analyzed separately by year as a RCBD using PROC MIXED in SAS software (Version 9.3 for Windows, SAS Institute, Cary, NC) employing data only from North Logan and Blue Creek in 2013. Entry means were separated using Fisher’s protected least-significant difference (LSD; α = 0.05) test to produce lsmeans, which were used in a multivariate principal component analysis (PCA) to define relationships among entries. Differences between entry types (e.g., check vs. rubra; Table 1) were tested by comparing entry type means directly, using LSD values to declare significance. For significant entry by year interaction effects, Spearman’s rank correlation coefficients were computed on the lsmeans using PROC CORR applying the Spearman option in SAS to determine if interactions were significant due to changes in magnitude or rank. To assess the strength of associations among the traits examined, Pearson product-moment correlation coefficients were also produced to identify associated traits (Robbins et al. 2016; Székely et al. 2007).

Genotyping and AFLP-based cluster analysis

The DNA extraction and quantification, amplified fragment length polymorphism (AFLP) analysis, and cluster analysis that were used to produce a neighbor-joining tree were accomplished according to Ma et al. (2014). Leaf samples of each accession were collected and lyophilized, then total cellular DNA was extracted and the AFLP procedure was performed using the same selective primers as Jones et al. (2008): E-ACAC/M-CTAC, E-ACAG/M-CTCA, E-ACAC/M-CTAG, E-ACAC/M-CTTC, E-ACCT/M-CTCT, E-ACTC/M-CTTG, E-ACT/M-CTA, E-ACT/M-CTG, E-ATA/M-CAA, and E-AGG/M-CGC. The AFLP present/absent genotypes were used to create an outgroup rooted neighbor-joining dendrogram using the Nei and Li average pair-wise genetic distance method (Nei and Li 1979) with PAUP computer software version 4.0b10 (Swofford 2003). Internal support for cluster groupings was assessed using 1000 bootstrap replications (Felsenstein 1985). The cultivar Dawson E was excluded from the analysis because the percentage of missing data was too high even after repeated attempts to obtain sufficient data for examination.

Ploidy estimation

The determination of ploidy level of parental stocks is critical to strategic selection of parents for hybrid production in grasses (Ruemmele et al. 2003). Thus, the ploidy level of each accession was determined by cytological examination of mitotic chromosomes at metaphase following the methodology of Jensen et al. (2006). At least three samples from each accession were treated and chromosomes were visually counted (Table 1).

Results

Morphological evaluation

A significant (P < 0.05) main effect of year was detected for all traits in Experiments 1 and 2, except for early biomass in Experiment 2. The main effect of entry was highly significant (P < 0.0001) for all traits in both Experiments 1 and 2. In Experiment 1, the year by entry interaction was not significant for vigor, persistence, and width, but was highly significant (P < 0.0001) for biomass, height, and the number of seeds per plant. In contrast, a significant (P < 0.01) year by entry interaction was detected for all traits in Experiment 2. In Experiment 2, the main effect of location was not significant for vigor, but marginally significant (P = 0.037–0.015) for early and late regrowth, and highly significant (P < 0.01) for early and late biomass, persistence, and seed number. A highly significant (P < 0.01) location by entry interaction was detected for all traits in Experiment 2. However, since Spearman’s rank correlation coefficients across locations ranked from 0.616 to 0.874 for all traits, this interaction was deemed to be based largely on magnitude rather than rank. Because of the detection of significant and numerous main effects due to year, results are presented separately by year for both Experiments 1 and 2 (Tables 1, 2). Moreover, since differences between locations in Experiment 2 were mostly based on magnitude and not rank, results are presented combined over locations for this experiment (Table 2).

Table 2 Mean values of phenotypic traits of Festuca accessions and checks evaluated in Blue Creek, UT from 2008 to 2011 (Expt. 1)
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Experiment 1 The mean values of all entries for all traits were significantly greater (P < 0.05) in 2011 than in 2010, except for persistence, which was significantly lower (Table 2). The mean of biomass in 2009 was not significantly different than in 2011, but was greater than in 2010. In contrast, the number of seeds per plant in 2009 was greater than in 2010, but lower than in 2011. Persistence was not significantly different between 2009 and 2010. On average, the F. rubra accessions PI 659899, PI 659946, PI 659950, PI 659954, PI 659965, PI 659966, PI 659981, and PI 659984 were not statistically different from the Festuca cultivar checks (i.e., Black Sheep, Cascade, Dawson E, Shademaster, Durar, and Scaldis) for any trait in any year, except for persistence in 2011 (F. rubra mean = 0.75 vs. Festuca check mean = 0.93). When compared to the best performing F. valesiaca accessions identified by Ma et al. (2014) (PI 659923, PI 659932, PI 670362, and PI 670364), the F. rubra accessions examined herein were not significantly different, except for seed yield in all years (20,527 vs. 5819 seeds/plant in 2009, 25,552 vs. 1890 seeds/plant in 2010, and 43,297 vs. 4462 seeds/plant in 2011) and vigor in 2010 (2.8 vs. 1.9), biomass in 2011 (112.4 vs. 70.1 g/plant), and persistence in 2011 (0.93 vs. 0.75). Only one F. rubra accession (PI 659984, CHN) consistently performed better or as well as the three F. rubra cultivar checks (Cascade, Dawson E, and Shademaster) in all 3 years (Table 1). However, the mean trait values of this accession were slightly lower than ‘Shademaster’ in 2011, though not significantly so for most traits. Compared to the best performing F. valesiaca accessions, PI 659984 exhibited significantly higher trait values for biomass, height, and width, and similar values for persistence in 2009 and 2010. However, mean persistence values for PI 659984 over years were not significantly different than the F. valesiaca accessions examined. Moreover, the mean seed number per plant of PI 659984 was significantly lower in all years tested. No significant difference was detected between PI 659984 and F. valesiaca entries for most traits in 2011.

Pearson correlation coefficients indicate that most traits were positively correlated, except for the number of seeds per plant (Table 4), and that trait correlations were generally higher in 2010 than in 2011. Seed number was correlated with vigor in 2010 (r = 0.661, P < 0.01) and biomass in 2011 (r = 0.494, P < 0.05). Likewise, vigor was highly positively correlated with all traits in 2010 (r = 0.661, P < 0.01 to r = 0.839, P < 0.001), though most correlations were not as high in 2011 (r = 0.359, not significant to r = 0.846, P < 0.001). The high positive correlations between biomass and height (r = 0.872, P < 0.001) and width (r = 0.756, P < 0.001) in 2010 were higher than in 2011 (r = 0.581, P < 0.01) and (r = 0.565, P < 0.01), respectively. Biomass was also correlated with persistence in both years (r = 0.502, P < 0.05 in 2010 and r = 0.527, P < 0.05 in 2011). Though persistence was correlated with all traits except seed number in 2010, significant correlations of persistence were only identified with vigor (r = 0.650, P < 0.01) and biomass (r = 0.527, P < 0.05) in 2011.

Least squares means of the traits examined were used in a PCA analysis (first three components) to assist in defining performance differences among entries across all traits (Fig. 1). While principal components (PC) 1 and 2 accounted for a combined 69.0% of the variation, PC3 provided an additional 13.2% to account for 82.2% of the observed variation. Based on the absolute value of the eigenvectors, the traits contributing the greatest influence on PC1 in order of contribution were height (2010), vigor (2010), vigor (2011), biomass (2011), and biomass (2010) (data not shown). The non-Festuca checks ‘Manhattan 4’ and ‘Coronado’ did not cluster near any other entries, while the Kyrgyzstan F. valesiaca entries PI 659923, PI 659932, PI 670362, and PI 670364 clustered apart from the rest of the Festuca entries. The F. rubra accessions PI 659899 (Kyrgyzstan), PI 659966 (Inner Mongolia CHN), and PI 659981 (Inner Mongolia CHN) grouped in relative proximity to each other compared to accessions PI 659946 (Kyrgyzstan), PI 659950 (Kyrgyzstan), PI 659954 (Kyrgyzstan), and PI 659965 (Inner Mongolia CHN), which were comparatively more dispersed. Although the best performing F. rubra accession, PI 659984 (8x, CHN), did not cluster near the other F. rubra accessions examined, it was somewhat proximate in position to the F. rubra cultivar Shademaster (8x).

Fig. 1
figure 1

Ordination after principal component analysis of all morphological characteristics taken collectively on Festuca accessions and checks evaluated in two experiments in Blue Creek, UT from 2008 to 2011 (Experiment 1) and in Malta, ID, Blue Creek, UT, and North Logan, UT from 2011 to 2013 (Experiment 2). The numbers in parenthesis along each axis indicate the percent variation explained by each principal component

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Experiment 2 To further examine F. rubra accession performance differences detected in Experiment 1, a morphologically diverse subset of the F. rubra accessions from Experiment 1 were evaluated at three locations (Malta, ID, Blue Creek, UT, and North Logan, UT) over 2 years (2012 and 2013). Because of rabbit predation at Malta ID in 2013, the only traits that could be compared between years across all locations and entries were vigor, early biomass, and persistence. Although mean values decreased (P < 0.05) between 2012 and 2013 with respect to vigor (2.6 vs. 2.2) and persistence (0.93 vs. 0.85), early biomass was not significantly different (19.03 vs. 19.25 g/plant) over years (Table 1). When compared across Blue Creek, UT and North Logan, UT, late biomass, early regrowth, and late regrowth increased from 2012 to 2013 (37.85 vs. 51.26, 12.51 vs. 14.61, and 2.72 vs. 4.97 g/plant, respectively), while the number of seeds per plant decreased (11,388 vs. 7185) (data for 2012 not shown; data for 2013 in Table 3). In 2012, the combined mean of the CHN F. rubra accessions (PI 659965, PI 659966, PI 659981, and PI 659984) of any trait was not significantly different from the combined mean of the Festuca cultivars (Black Sheep, Shademaster, Durar, and Covar). However, the mean of the F. rubra accessions taken collectively was significantly lower than the mean of the checks for all traits in 2013, except seed number. Similarly, the mean of these CHN F. rubra accessions was not different from the mean of the four paired cross F. valesiaca or F. valesiaca × F. ovina hybrids (R4S4, R4S6, R4S22, and R4S32) in 2012 for any traits, except early biomass (15.09 vs. 23.07 g/plant). Nevertheless, these F. rubra accessions performed lower than the hybrids in all traits, except seed number and late regrowth in 2013. The best performing F. rubra accession in Experiment 1 (PI 659984) was also the best performer in Experiment 2. Similar to Experiment 1, this accession did as well as or better than the Festuca controls for most traits in both years. However, the mean trait values for PI 659984 were significantly lower than the best performing Festuca cultivar (Durar) in 2013 with respect to early biomass (12.97 vs. 29.61 g/plant) and late regrowth (2.82 vs. 9.60 g/plant). Compared to the best performing Festuca hybrid evaluated (R4S22; F. valesiaca × F. ovina), PI 659984 was similar in 2012 for vigor, late biomass, and persistence, and higher in seed number (10,792 vs. 16,201), but it was lower in early biomass (32.19 vs. 22.03 g/plant), early regrowth (16.96 vs. 13.00 g/plant) and late regrowth (6.28 vs. 3.03 g/plant). In 2013, however, PI 659984 was lower than R4S22 for all traits, although not significantly so for persistence.

Table 3 Mean values of phenotypic traits of Festuca accessions and checks evaluated in 2012 and 2013 in three locations (Malta, ID, Blue Creek, UT, and North Logan, UT) (Expt. 2)
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Table 4 Pearson correlation coefficients of phenotypic traits of Festuca accessions and checks evaluated in two experiments (Expts. 1 and 2) in Blue Creek, UT (Expt. 1) in 2010 (top diagonal) and 2011 (bottom diagonal) and in Malta, ID, Blue Creek, UT, and North Logan, UT (Expt. 2) in 2012 (top diagonal) and 2013 (bottom diagonal)
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While several trait correlations in Experiment 2 were similar to those in Experiment 1, there were some notable differences (Table 4). As with Experiment 1, vigor and late biomass were positively correlated (r = 0.674–0.948; P < 0.05) with most traits in both 2012 and 2013, as was early biomass (r = 0.627–0.956; P < 0.05). In contrast to Experiment 1, persistence was not correlated with any trait in 2012, but positively correlated (r = 0.577–0.765; P < 0.05) with all traits except seed number and late regrowth in 2013. Also, seed number was correlated with most traits except persistence both years and late regrowth in 2012. Early regrowth was positively correlated (r = 0.577–0.961; P < 0.05) with all traits both years, except for persistence in 2012. Late regrowth was highly positively correlated with early regrowth [r = 0.745, P < 0.01 (2012) and r = 0.849, P < 0.001 (2013)], but, by comparison, was less correlated with other traits (e.g., vigor and persistence).

No distinct trait-based groupings could be identified among entries after PCA (Fig. 1). The total variation explained by the first three PCs was 86%, where PCs 1 and 2 accounted for 75.4% of the variation. Eigenvector values indicated that early regrowth (2013), early biomass (2012), late biomass (2013), seed number (2013), early regrowth (2012), and vigor (2013) had the greatest influence on the spatial orientation in the first component (data not shown). Where PI 659981 (6x, Inner Mongolia CHN) was in relatively close spatial proximity to the Festuca cultivars Shademaster (8x) and Black Sheep (6x), PI 659965 (6x, Inner Mongolia CHN) and PI 659966 (6x, Inner Mongolia CHN) were not spatially associated with these cultivars and were themselves distinct from the other accessions examined. In contrast to Experiment 1, PI 659981 did not associate with PI 659965 and PI 659966. However, similar to Experiment 1, PI 659984 (8x, Qinghai CHN) did not cluster with the other F. rubra accessions examined. Although the four F. valesiaca or F. valesiaca × F. ovina hybrids were spatially distinct and not in close proximity to each other or the Ovina complex cultivars Black Sheep, Durar, and Covar, hybrids R4S6 and R4S32 were in relative close proximity to each other.

Genotypic analysis

The genetic similarity among the Festuca accessions and cultivars included in Experiment 1 was assessed using AFLP marker analysis. Ten AFLP selective amplification primer combinations produced 1515 consistently bright, polymorphic bands (an average of 151.5 polymorphic markers per primer combination). A mid-point rooted (‘Coronado’ and ‘Manhattan 4’) neighbor-joining tree constructed from Nei and Li genetic distance estimates (Fig. 2) resulted in the predictable partitioning of entries into Rubra and Ovina Complex groupings at Node 1. The Ovina Complex group, consisting of hexaploid and diploid entries, was further divided at Nodes 3 and 5, where Node 3 partitioned cultivars Black Sheep (2x, F. ovina) and Scaldis (6x, F. trachyphylla) from a bifurcate cluster (Node 5) consisting of diploid F. valesiaca entries (4) collectively and the cultivar Durar (6x, F. trachyphylla). Rubra Complex accessions were divided at Node 2 into subspecies with ‘Cascade’ (6x, F. rubra subsp. commutata) residing in a single clade and a bifurcate cluster containing seven hexaploid and two octoploid (‘Shademaster’ and PI 659984) F. rubra accessions (Node 4). The hexaploid accessions were further divided into two geographically unique clades (Node 6) consisting of accessions from Inner Mongolia CHN (4) and Kyrgyzstan (3).

Fig. 2
figure 2

Rooted neighbor-joining tree illustrating genetic relationships among Festuca accessions and checks based on Nei and Li’s (1979) genetic distance among AFLP profiles. Numbers at each node indicate bootstrap values after 1000 bootstrap permutations (Swofford 2003). Letters after accession names indicate species where ar = Schedonorus arundinaceus, ov = F. ovina, pe = Lolium perenne, ru = F. rubra, ruco = F. rubra subsp. commutata, tr = F. trachyphylla, and va = F. valesiaca, and numbers in parenthesis after the species designation indicate ploidy level

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Discussion

Festuca species have been considered for use in low maintenance roadside and golf course applications, railway embankments, and reclamation on disturbed landscapes (Weibull et al. 1991). Some species of the genetically variable fine-leaved Ovina and Rubra complexes possess considerable abiotic stress tolerances (Aronson et al. 1987; Kanapeckas et al. 2008; Wallner et al. 1982), and certain F. rubra species may possess ruminant forage value (Bovolenta et al. 2008; Carrère et al. 2010) and wildfire resilience (Fernández-Abascal et al. 2003; Musser 1947) under rangeland conditions. We present herein a morphological assessment of recently collected Asian F. rubra and F. valesiaca accessions originating from heavily grazed semi-arid growing environments where water is often severely limiting. These accessions showed variable phenotypic responses under several western U.S. rangeland growing environments.

Incorporation of these phenotypic characteristics will be increasingly important as improved plant materials are developed for sustained productivity on novel ecosystems (i.e., emergence of species that occur in combinations and relative abundances that have not occurred previously within a given biome) that are emerging on western U.S. rangelands (Choi et al. 2008). Novel ecosystems are also emerging in the areas where collections where made in China and Kyrgyzstan. In China, for instance, 50-year records of cooling in its subtropical zones (southern China; 0.14–0.34 °C/decade) and warming in temperate zones (northern China; 0.20–0.27 °C/decade) are indicative of changing climates in its agricultural growing regions (Shen and Varis 2001). Similarly, changes in climatic conditions in Kyrgyzstan are typified by temperature increases, as documented by the retreat (>32% between 1955 AND 1999) of glaciers in the northern Tien Shan province (Bolch 2007). Predictions by climate change models for U.S. semi-arid rangelands likewise indicate hotter and drier conditions (Christensen et al. 2007), which could increase the already high rate of rangeland degradation (D’Antonio and Vitousek, 1992).

The F. rubra collections characterized herein were obtained in the semi-arid Cholpon-Ata region of Issyk-Kul (2327 m elevation; annual precipitation = 205 mm), in the Kochkorka region of Naryn (3056–3221 m elevation; annual precipitation = 278 mm) and in the Panfilov and Dzhaiyl regions of Chuy (2425–2978 m elevation; annual precipitation = 300–400 mm) provinces of Kyrgyzstan (Johnson 2006a, b). Collections made in CHN originated from the Qinghai Province (~3000 m elevation; annual precipitation = 200 mm) and Keshiketeng County Chifeng Inner Mongolia (1309–1313 m elevation; annual precipitation = 371 mm). In Issyk-Kul Kyrgyzstan, collections were made along river bottoms and meadow openings associated with spruce forests in granite and loam soils. While Naryn collections were made in the harsh environment of Tien Shan at the Son-Kel River Pass and near lake Son-Kel, Chuy collections were obtained in the Suusamyr Valley between the Suusamyr Too and the Kyrgyz Ala-Too ranges of the Tien Shan mountains along stony roadsides and grassy steppes in dry gravely and loamy soils. In contrast, China collections (e.g., PI 659984) were made near the Haolaihule village in lowland areas between sand dunes and hilly meadows in sandy and clay loam soils and in the foothills of the Tibetan Plateau (Qinghai-Tibet Plateau).

In the main, the Kyrgyzstan and CHN collection environments are harsher (i.e., annual precipitation and/or temperature) than those of Blue Creek and North Logan UT, but comparable to Malta ID. In Blue Creek and Malta (specific location data not presented), plants of F. rubra PI 659984 (Qinghai, CHN) were persistent, vigorous, possessed substantial regrowth attributes after an initial early season biomass harvest, and consistently produced an abundant amount of seeds. The performance of other Asian F. rubra accessions (e.g., PI 659981, Inner Mongolia, CHN) was also noteworthy. Thus, it appears that some of the Asian F. rubra accessions examined herein may possess genes for abiotic stress tolerance (e.g., heat, drought) predictive of their origins.

Festuca rubra is used in low input turfgrass applications in China, where various species exhibit cold (Sun et al. 2008a) and salt (Liu et al. 2001) tolerance, and thus are potential genetic sources for plant improvement (Campbell and Xia 2002). As in the western U.S., mixed perennial gramineous grasses have been used in China for rehabilitation of degraded sites in desertified areas (He et al. 2008). Festuca rubra species have been found to either contribute effectively (Su and Zhang 1997) or ineffectively (He et al. 2008; Sun et al. 2008b) when used in grass mixtures for rehabilitation of such Chinese landscapes. Likewise, F. rubra species may (Bezeau and Johnston 1962; Van Ruijven and Berendse 2003; Smith and Bradshaw 1979) or may not (Pontes et al. 2007; Khaled et al. 2006) possess forage value and/or contribute to species richness for grazing ruminants depending on growing environment (e.g., season, rangeland or pasture, minelands) and management requirements (e.g., irrigated or non-irrigated applications).

Wildfires are most prevalent in the western U.S. during July and August (Dibble et al. 2007; Littell et al. 2009). Greenstrips (typically ~91 m wide) can modify wildfire effects and behavior to control wildfire speed and spread (Pellant 1994; Finney et al. 2007). Characteristics of perennial grasses suitable for use in greenstrips include livestock and wildlife palatability as well as an ability to establish and persist, a low growth habit, and a propensity for high ignition temperatures and low burning intensities (i.e., relatively high water content) (Pellant, 1994). Under the harsh growing conditions of Malta, ID, plants of PI 659984 remained green through August and early September until frost (Fig. 3). This “stay green” characteristic is in stark contrast to typical bunch type perennial gasses currently used in the western U.S. as greenstrip components, which typically senesce in July becoming fuel for wildfires (Monsen 1994; Pellant 1994). Thus, since the stay green trait may provide a for high ignition rates and low burning intensity, rhizomatous PI 659984 or its derivatives may be attractive genetic resources for incorporation into western U.S. rangeland greenstrips.

Fig. 3
figure 3

Festuca rubra L. accession PI 659984 (People’s Republic of China, 8x) as observed in Malta, ID in August (A) and September (B) 2012 illustrating green color and rhizomes under harsh western US semi-arid growing conditions. Few or many indicates fewer or many rhizomes, respectively, in relation to a plant stake (30 cm). (Color figure online)

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Plants of F. rubra Ps PI 659984 and 659981 segregated for the frequency and intensity of tussock “dead centers” (lack of regrowth) during our experimentation (data not presented). Dead centers manifested themselves after early and/or late harvesting and were often prominent after several seasons of growth (Fig. 4). The rhizomatous growth typical of F. rubra plants possessing dead centers resulted in a vegetative ring (10–30 cm in diameter) that enclosed bear ground where dead centers appeared. Although markedly smaller in size, this vegetative ring growth habit is similar to that of Muhlenbergia torreyi (Kunth) Hitchc. ex Bush (ring muhly). Plants possessing such ring growth characteristics may or may not be desirable components of greenstrips for wildfire control. Thus, it will be important evaluate the value of ring and non-ring producing rhizomatous segregates derived from PI 659984 and 659981 for their performance as grass components in greenstrips. Likewise, derivatives from PI 659984 and 659981 will need to be evaluated for their palatability and forage value under intensive western U.S. rangeland grazing conditions.

Fig. 4
figure 4

Festuca rubra L. accession PI 659984 (People’s Republic of China, 8x) as observed in Nephi, UT (annual precipitation = 305 mm) showing segregates with dead center (A) and continuous grass mat (B) in August 2016 after being mowed in 2015 and 2016. Plant size defined in relation to a measuring tape (yellow portion 30 cm). (Color figure online)

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