Abstract
In recent years, turfgrass breeders have given increased attention to the development of lower maintenance turfgrass cultivars. Fine fescues (Festuca spp.) have been identified as potential candidate species for low-maintenance lawns because of their reduced need for water, mowing, and fertilizer. Unfortunately, these species have some weaknesses that must be improved to facilitate their use; perhaps, the most important of these is tolerance to wear and traffic. For this trait to be improved in new cultivars, there must be sufficient heritable variation available for plant breeders to exploit; however, little is known about the heritability of this complex trait in fine fescue species. Therefore, the objective of this study was to determine the heritability of wear and traffic tolerance in three fine fescue species. Replicated field studies were established in North Brunswick, NJ, and St. Paul, MN, and each included 157 Chewing’s fescue (Festuca rubra L. subsp. fallax), 155 hard fescue (Festuca brevipilia), and 149 strong creeping red fescue (F. rubra L. subsp. rubra) genotypes. Wear tolerance was evaluated in North Brunswick and traffic tolerance was evaluated in St. Paul during 2015 and 2016 using different simulators to determine both plant performance and broad-sense heritability estimates for wear and traffic tolerance. Broad-sense heritability estimates for the three species when calculated on a clonal basis was between 0.69 and 0.82 for wear tolerance in the North Brunswick location and between 0.49 and 0.60 for traffic tolerance in the St. Paul location. On a single-plant basis, broad-sense heritability estimates for the three species were between 0.31 and 0.45 for wear tolerance in the North Brunswick location and 0.09 and 0.12 for traffic tolerance in St. Paul. However, this research does indicate that improvement of wear and traffic tolerance in fine fescues is possible through recurrent breeding methods based on selection of replicated clonally propagated genotypes rather than selection of single individual plants of a population. This was the first study to determine the genetic effects of wear and traffic tolerance in any turfgrass species.
Historically, there has been a high consumer expectation for turfgrass quality and performance in home lawns and landscapes leading to greater fertilizer use and water consumption over the years (Osmond and Hardy, 2004). Interest in conserving natural resources has grown within both the public sector and various political groups (Hamrick, 2016). As restrictions on pesticide and water use on turfgrass landscapes become more prevalent, there will be increased demand for sustainable solutions. Yue et al. (2017) showed that many consumers are environmentally conscious and would be willing to pay more for low-maintenance grasses, which suggests that turfgrass breeders should devote more resources to the development of low-input turfgrass species.
Fine fescues (Fescue spp.) are considered to be among the best low-maintenance cool-season turfgrasses (Bonos and Huff, 2013; Dernoeden et al., 1994) and provide a number of benefits for low-input turf uses. Fine fescues are generally adapted to dry, shady, low pH conditions, and perform best in well drained soils that are not saturated (Bertin et al., 2009; Rummele et al., 2003). Fine fescues can develop dense, fine turf cover requiring low amounts of water, fertilizer, and pesticides.
Three of the fine fescue species most widely used for turfgrass areas are strong creeping red fescue (F. rubra L. subsp. rubra), Chewing’s fescue [F. rubra L. subsp. fallax (Thuill.) Nyman], and hard fescue (F. brevipilia Tracey). Strong creeping red fescue has a rhizomatous growth habit which aids in recovery when leaf tissue is severely damaged; however, it does not have high levels of drought tolerance when compared with other fescue species such as hard fescue (Smith et al., 2010) and does not produce turf as dense as Chewing’s and hard fescues. Strong creeping red fescue is also more susceptible to dollar spot (caused by Sclerotinia homoeocarpa F.T. Benn), red thread [caused by Laetisaria fuciformis (McAlpine) Burds.] and leaf spot diseases (caused by Bipolaris spp.) than Chewing’s and hard fescues (Han et al., 2003; Shortell et al., 2005). Chewing’s fescue is a bunch-type grass able to withstand lower mowing heights than most other fine fescues, allowing it to be used on golf courses (Watkins et al., 2010). Hard fescue, also a bunch-type grass, has been shown to perform the best out of all the fine fescue species in low-maintenance situations and usually maintains its dark green color longer in drought conditions (Cortese et al., 2011), especially on sandy, well-drained soils. However, in heavier soils, hard fescue can be severely affetced by summer patch disease (caused by Magnaportheopsis poae Landschoot and N. Jackson).
For low-input turfgrasses to be useful they also need to meet the demands required of turf landscapes, such as recreational uses in home lawns, parks, or athletic fields. This includes the ability to withstand and maintain quality under wear and traffic conditions. Turfgrass traffic tolerance is made up of two components: wear and compaction (soil surface disruption) (Beard, 1973). Wear stress includes tissue tearing, tissue bruising, and tissue removal resulting from horizontal forces, whereas surface soil disruption includes soil compaction and displacement as a result of vertical forces (Vanini et al., 2007). Therefore, it is important to distinguish between the two types of traffic when developing a turfgrass. Most traffic tolerance research in turfgrass systems has focused on higher maintenance situations such as athletic fields (Brosnan et al., 2005; Carroll and Petrovic, 1991; Samaranayake et al., 2008).
Wear or traffic tolerance is a critical need in fine fescue development, especially because fine fescues are known for their poor performance under wear or traffic conditions. They lack traffic tolerance and have very slow recuperative ability compared with other cool-season turfgrasses (Bonos and Huff, 2013). In fact, they are often not used in high traffic areas. This attribute was also found to be the most important to consumers (Yue et al., 2017), so it is important to improve wear/traffic tolerance in fine fescues that otherwise perform at acceptable levels under low maintenance. A few recent studies have shown that fine fescues have the potential to perform well under wear in low-maintenance situations (Cortese et al., 2011; Horgan et al., 2007; Watkins et al., 2010). In addition, considerable genetic variability in wear tolerance (Bonos et al., 2001; Cross et al., 2013) or traffic tolerance (Chen et al., 2014) has been observed within the fine leaf fescues under medium maintenance management. However, no research has been conducted to characterize the genetic contribution of wear or traffic tolerance in any turfgrass species.
Understanding the genetic and environmental effects on the phenotypic expression of a trait is useful to develop a breeding strategy to improve the trait. Heritability determines the amount of variability in the phenotype that is due to genetic and environmental factors. Heritability calculations give a measure of the genetic component controlling the phenotype, so the larger the value of heritability, the more quickly and less intensively improvement of a trait can be made (Nyquist and Baker, 1991). Breeders can only manipulate genetic factors and, therefore, a large genetic component is desired over a large environmental component which cannot be influenced by selection. Because heritability estimates are not known for traffic or wear tolerance in any turfgrass species, the objective of this study was to estimate the variance components and broad-sense heritability of wear and traffic tolerance in three of the most widely used fine fescue species.
Materials and Methods
Plant propagation and field trial establishment.
Individual genotypes of Chewing’s fescue (157 total), hard fescue (155), and strong creeping red fescue (149) were selected from improved breeding material from the turfgrass breeding program at Rutgers University and the New Jersey Agricultural Experiment Station and from several commercial cultivars. Breeding material consisted of individual plants selected from several hundred half-sib progeny turf plots that exhibited superior performance in mowed turf plots; seed used to establish these turf plots originated from numerous isolated polycrosses. Commercial cultivars (four of each of the three fine fescue species) were represented by 12 individual genotypes. In total, one-third of the genotypes in this study originated from commercial cultivars and the remaining were from breeding material. Single tillers were propagated from each genotype and then transplanted to 6.4- by 6.4-cm cell flats filled with BX potting media (Pro-Mix HP; K.C. Shafer, York, PA). After these plants reached the multiple tiller stage (≈2 months), each individual plant (clone) was split evenly into two ramets. One ramet of each clone was separated equally into six vegetative replications and maintained under greenhouse conditions for 6 months. The other ramet was sent to the University of Minnesota where it was split into six vegetative replications as mentioned previously. This provided enough plant material to establish two field trials in randomized complete block designs with six replications at each location (described in the following paragraphs).
Wear tolerance trial.
The wear tolerance trial was conducted on a Nixon loam (fine-loamy, mixed, and mesic Typic Hapludults) at the Rutgers Turfgrass Research Facility at Horticultural Farm #2 in North Brunswick, NJ. The trial was seeded to Stellar GLR perennial ryegrass (Lolium perenne) maintained with 16–0–8 granular N–P–K fertilizer (2.44 g N/m2) in the fall of 2013. The plants were transplanted into the field within the established ryegrass stand in June 2014 on 38 cm spacing with a tubular turf plugger (Turf-Tec Intl., Tallahassee, FL). Supplemental watering was applied as needed to ensure establishment and avoid severe drought stress. Fungicides (cyazofamid and boscalid) were applied monthly from May to August to preventatively control diseases so that wear responses were not confounded by disease presence. The trial was maintained at 7.62-cm mowing height. Before wear applications, the ryegrass stand and fine fescues were treated with fluazifop herbicide (1000 g a.i./ha) every 6 weeks during the growing season to selectively retard the growth of the perennial ryegrass while at the same time not injuring the fine fescue clones. This allowed the fine fescue clones to grow to their full potential without competition from the perennial ryegrass groundcover because fine fescues are resistant to fluazifop herbicide effects. It also allowed full exposure of the fine fescues to wear/traffic forces. Wear was applied using the Rutgers Wear Simulator (Park et al., 2016), a 0.8-m-wide wear simulator constructed from a modified walk-behind power broom (Sweepster; LLC, Dexter, MI) as described by Bonos et al. (2001) (Fig. 1A). This machine applies wear without causing soil compaction. Treatments consisted of two passes of the wear simulator applied once a week for 6 weeks (12 passes in total) from mid-September through Oct. 2015 and 2016.
Comparisons of wear [New Jersey (A)] and traffic [Minnesota (B)] simulators used to evaluate fine fescue species for wear and traffic tolerance.
Citation: HortScience horts 53, 4; 10.21273/HORTSCI12450-17
Comparisons of wear [New Jersey (A)] and traffic [Minnesota (B)] simulators used to evaluate fine fescue species for wear and traffic tolerance.
Citation: HortScience horts 53, 4; 10.21273/HORTSCI12450-17
Comparisons of wear [New Jersey (A)] and traffic [Minnesota (B)] simulators used to evaluate fine fescue species for wear and traffic tolerance.
Citation: HortScience horts 53, 4; 10.21273/HORTSCI12450-17
Traffic tolerance trial.
The traffic tolerance trial was conducted on a Waukegan silt loam (fine-silty over sandy, mixed, and mesic Typic Hapludoll) at the Turfgrass Research, Outreach, and Education Center at the University of Minnesota in St. Paul, MN. The trial was planted into established “Champ GQ” perennial ryegrass, maintained with Sustane 15–3–9 granular N–P–K fertilizer (2.44 g N/m2), irrigated at establishment, and sprayed with clopyralid herbicide for control of broadleaf weeds. This trial was maintained at 7.62-cm mowing height and treated with fluazifop to retard the ryegrass before traffic treatment, similar to those methods described previously for the wear tolerance trial. Fine fescue clones were trafficked with a custom-built golf cart traffic simulator towed behind a turf utility vehicle which had been used successfully in previous studies to simulate traffic (Horgan et al., 2007; Watkins et al., 2010). The traffic simulator consisted of two 454-kg traffic units on an axle containing five golf cart tires. This simulator imparts both wear and soil compaction to the turf, thus simulating golf cart traffic of two golfers and equipment on pneumatic tires (Alderman, 2016) (Fig. 1B). Traffic was applied 3 d each week beginning mid-September through Oct. 2015 and 2016. Plots received two passes of traffic on each day for a total of six passes of traffic each week (36 passes total).
Wear/traffic assessment.
Assessment of wear/traffic quality was made during October/November of 2015 and 2016. Turf quality was based on a 1–10 scale with 10 = no effect and 1 = clone death. The turf quality rating contained elements of density, and bruising or discoloration of plant tissues. A visual guide of the quality rating was developed to allow raters at both locations to have a uniform rating scale. At the North Brunswick location, diameters (centimeters) of clones were taken before and after wear application to evaluate reduction in size of plants due to wear. Diameters were determined by measuring across the clone from edge to edge of the base of the plant using a ruler.
Statistical analysis.
Because of differences in the type of wear (New Jersey) or traffic (Minnesota) that was applied, data were analyzed and presented separately for wear and traffic. Data were subjected to analysis of variance (ANOVA). Wear and traffic quality mean separation was achieved by a paired t test (α = 0.05) with Bonferroni method for correction of multiple comparison. Broad-sense heritability for wear or traffic tolerance was determined by means of variance components calculated from expected means squares from the ANOVA. Data from each year were analyzed separately using the lme4 version 1.1–12 in R with all sources of variation considered as random effects. Wear (and traffic) performance was analyzed as a randomized complete block for 1 year or split plot in time for 2 years. Variance components were obtained by a model summary function in lme4 package. Estimates of heritability were determined and their se were determined using a simulation method by refitting the model 1000 times using parametric bootstrap samples by applying the simulate and refit functions of the lme4 package to estimate the distribution of heritability (Yousef et al., 2015).
where σ2g equals the variance of genotypes, σ2p equals the phenotypic variance, σ2dg equals the variance of dates × genotypes, σ2gr equals the variance of genotypes × replications, σ2e equals the error variance, D equals the number of dates, and R equals the number of replications (Yousef et al., 2015).
Results and Discussion
Species response to wear.
At North Brunswick, hard fescue received the highest average wear quality rating of (4.1 and 4.9, for 2015 and 2016, respectively), followed by Chewing’s fescue (4.0 and 4.6), and strong creeping red fescue (4.0 and 4.3) (Table 1). These results were similar to those found in other studies when full turf plots were worn (Cross et al., 2013; Smith et al., 2010), but contrasted with Bonos et al. (2001) who reported that strong creeping red fescues performed better than hard fescue under simulated wear. Cross et al. (2013) suggested that change in the ranking of species was due to increased breeding and selection work performed with hard and Chewing’s fescue during the early 2000s. In our trial, posttreatment quality ratings were higher in 2016 than 2015 and had a more uniform distribution (data not shown). In addition, there were no significant differences between species in 2015 but in 2016, hard fescue was greater than Chewing’s fescue which was greater than strong creeping red fescue. This would indicate that plants that were more mature and larger in size (Table 2) generated a greater resolution in wear quality within the species and suggesting that evaluation of fine fescues on mature plants is preferable. Indeed, studies have shown that different morphological states (Dowgiewicz, 2009) and physiological changes due to season of wear (Chen et al., 2016; Murphy and Ebdon, 2013; Park et al., 2010) can cause changes in wear tolerance of grasses. This study was conducted in the fall; the fall season was chosen for this study because Chen et al. (2016) showed that fine fescues subjected to traffic in the fall showed increased leaf bruising or discoloration of leaf tissue. The response of fine fescues to wear in different seasons could change evaluation parameters, species differences, and the effectiveness of selection.
Wear and traffic quality means of fine fescues in New Brunswick, NJ, and St. Paul, MN, in 2015 and 2016 post wear and application.
Diameters of fine fescues in New Brunswick, NJ, in 2015 and 2016 prior and post wear application with net change.
Species response to traffic.
In St. Paul, the average traffic quality ratings for 2015 and 2016 were as follows: hard fescue received the highest average rating (4.5, 4.7), followed by strong creeping red fescue (4.3, 4.6), and Chewing’s fescue (4.2, 4.8) (Table 1). Although, there was significance between the species for traffic tolerance in Minnesota, it was not consistent between years and in fact, Chewing’s fescue was significantly better than hard fescue in 2016, whereas strong creeping red fescue had the lowest traffic tolerance. Not surprisingly, we found very poor correlation for entry performance between the two sites (r-values = 0.24421; P = 0.001), indicating it may be difficult to identify clones with both wear and traffic tolerance. It is realized that growing environment may also play a role in the species and clone performance at the different locations.
Other researchers have found that cultivars performed differently for traffic tolerance based on location (Murphy and Ebdon, 2013; NTEP, 2009a, 2009b). The two machines used in our study applied traffic/wear to the turf in different ways. Brosnan et al. (2005) proposed that wear differences for an entry could be due to methods used to apply wear (i.e., simulator), duration of wear, and the intensity of wear. Greater traffic intensity has been shown to be required to change the ranking between species more so than between cultivars of the same species (Bourgoin and Mansat, 1981). This makes selection for traffic and wear tolerance more difficult as it is affected by a combination of methods used to impose wear, the evaluation procedure, and the wear intensity (Murphy and Ebdon, 2013). In the case of this study, as with all heritability studies, the heritability estimates can only be truly applied to the population and study the estimates were derived from. However, the estimates can give researchers an idea as how to implement the knowledge gained and methods that might be useful to improve selection for wear and traffic tolerance.
Broad-sense heritability.
Moderate to high broad-sense heritability estimates (0.69–0.82) for wear tolerance in fine fescues were calculated from the North Brunswick location (Table 3). Heritability estimates of wear tolerance on a clonal basis were 0.69 ± 0.04 for hard fescue, 0.73 ± 0.05 for Chewing’s fescue, and 0.82 ± 0.03 for strong creeping red fescue (Table 3). On a single-plant basis, the estimates were 0.35 for hard fescue, 0.31 for Chewing’s fescue, and 0.45 for strong creeping red fescue. The broad-sense heritability estimates for traffic tolerance in St. Paul were considerably lower (0.49–0.60) (Table 4). Heritability estimates for traffic tolerance on a clonal basis were 0.49 ± 0.09 for hard fescue, 0.57 ± 0.07 for Chewing’s fescue, and 0.60 ± 0.06 for strong creeping red fescue. On a single-plant basis, the estimates were 0.09 for hard fescue, 0.12 for Chewing’s fescue, and 0.11 for strong creeping red fescue.
Analysis of variance (ANOVA) and broad-sense heritability estimates (H) of wear quality of fine fescue entries evaluated in North Brunswick, NJ, in 2015 and 2016.
Analysis of variance (ANOVA) and broad-sense heritability estimates (H) of traffic quality of fine fescue entries evaluated in St. Paul, MN, in 2015 and 2016.
Heritability estimates for wear tolerance were higher and less variable than the heritability estimates for traffic tolerance (Table 5). Data for wear tolerance from the North Brunswick location followed a more standard bell curve than data from the traffic tolerance trial at St. Paul which was less evenly distributed. This could have been due to variability in the different machines used to impose wear and traffic as well as the soil differences throughout the field that may have affected the amount of soil compaction and related stresses that the traffic simulator may have caused.
Broad-sense heritability estimates (H) of wear (NJ) and traffic (MN) quality of all species and locations.
Genetic improvement through breeding has made an impact on fine fescue performance, but it seems to have less of an impact than in other turf species. This may be due to less breeding effort given to the fine fescues but more likely by the complexity of the genomes present in fine fescues: hard and Chewing’s fescue are hexaploids (2n = 6x = 42), whereas the strong creping red fescues are typically octoploids (2n = 8x = 56) (Huff and Palazzo, 1998).
This is the first report of heritability estimates for wear or traffic tolerance in any turfgrass species. The heritability estimates reported here suggest that selection for wear tolerance in fine fescues is possible as the variation observed was mainly due to genetic effects (Tables 3 and 4). This research supports the findings of Cross et al. (2013) who showed that wear tolerance had increased in a fine fescue breeding program after years of general quality selection. The low single-plant heritability we found suggests that selection for wear tolerance should be performed on replicated vegetative clones to account for the environmental variation associated with wear tolerance. For species such as fine fescues that can be vegetatively propagated, clonal replications are more simply obtained compared with species for which replicated progeny must be used, but breeders will still be limited by field space and time constraints to evaluate replications. This is even more important for selection for traffic tolerance. Heritability estimates were relatively low for traffic tolerance (0.49–0.60), indicating that the environment has a strong effect on the observed variation. There are more factors involved in traffic than in wear, so the added components (i.e., associated soil compaction) could be the cause of the lower heritability estimates observed. Some progress may occur, but the improvements may take longer and environmental effects should be controlled as much as possible to increase traffic tolerance among fine fescues. Interestingly, although regardless of whether wear or traffic was applied, the strong creeping red fescues exhibited the highest heritability estimates, indicating that selection would be most effective in this species. This is important because strong creeping red fescues were shown in both locations (Table 1) to have the lowest tolerance to both wear and traffic; in essence, selection would be most effective where progress is needed most.
For a trait as complex as wear or traffic, the heritability estimates are in a range similar to estimates found for disease resistance in other turfgrasses, although lower than estimates for dollar spot in creeping bentgrass (Agrostis stolonifera) (H = 0.90) (Bonos et al., 2003) and gray leaf spot (Magnaporthe grisea) in perennial ryegrass (H = 0.92) (Bonos et al., 2004) which are under strong genetic control. Nevertheless, given the complexity of wear and traffic tolerance, this research is promising to breeders in that improvements should be possible for wear and traffic tolerance in the fine fescues.
Conclusions
Although fine fescues presently make up a small percentage of the overall turfgrass seed industry (USDA, 2012), as environmental stewardship increases, and natural resources become scarcer, these low-input species will see an increasing role in sustainable turfgrass management. Through increased breeding efforts and the continued increase in knowledge of the inheritance of important traits in these grasses, the usefulness of these species in the industry will improve. Interestingly, our findings as shown by the variances obtained for “clone” (Tables 3 and 4) illustrate the presence of a significant amount of genetic variation among different fine fescue genotypes for wear tolerance (Table 3) and somewhat less for traffic tolerance (Table 4). Moderate to high wear heritability estimates indicate that a phenotypic recurrent selection program using replicated genotypes should be an effective tool in breeding for wear tolerance in fine fescue. Traffic tolerance showed lower heritability estimates and will have less response to breeding efforts. Traffic type and machinery used may influence selection, and environmental conditions will need to be closely examined to determine the proper techniques to develop cultivars that have more wear and traffic tolerance and can be used in a wider range of applications and environments. From the results presented in this study, the use of a wear simulator reduces variation involved with selection and may increase the improvement of the fine fescues as compared with a simulator which imparts both aspects of traffic.
Literature Cited
Alderman, J. 2016 The effect of management practices on buffalograss divot recovery and tolerance to golf cart traffic. Kansas State Univ., Manhattan, MS Diss
Beard, J. 1973 Cool season turfgrasses, p. 54–131. In: Turfgrass: science and culture. Prentice-Hall, Englewood Cliffs, NJ
Bertin, C., Senesac, A.F., Rossi, F.S., DiTommaso, A. & Weston, L.A. 2009 Evaluation of selected fine-leaf fescue cultivars for their turfgrass quality and weed suppressive ability in field settings HortTechnology 19 660 668
Bonos, S.A., Casler, M.D. & Meyer, W.A. 2003 Inheritance of dollar spot resistance in creeping bentgrass Crop Sci. 43 2189 2196
Bonos, S.A. & Huff, D.R. 2013 Cool-season grasses, p. 628–633. In: J.C. Stier, B.P. Horgan, and S.A. Bonos (eds.). Turfgrass: Biology, use, and management. Agron. Monogr. 56. ASA, CSSA, SSSA, Madison, WI
Bonos, S.A., Kubik, C., Clarke, B.B. & Meyer, W.A. 2004 Breeding perennial ryegrass for resistance to gray leaf spot Crop Sci. 44 575 580
Bonos, S.A., Watkins, E., Honig, J., Sosa, M., Molnar, T., Murphy, J. & Meyer, W. 2001 Breeding cool-season turfgrasses for wear tolerance using a wear simulator Intl. Turfgrass Soc. Res. J. 9 1 137 145
Bourgoin, B. & Mansat, P. 1981 Artificial trampling and players traffic on turfgrass cultivars. Proc. IV Intl. Turfgrass Res. Conf. Ontario Agr. College, Univ. Guelph Intl. Turfgrass Soc. 4:55–63
Brosnan, J.T., Ebdon, J. & Dest, W. 2005 Characteristics in diverse wear tolerant genotypes of Kentucky bluegrass Crop Sci. 45 5 1917 1926
Carroll, M.J. & Petrovic, A.M. 1991 Wear tolerance of Kentucky bluegrass and creeping bentgrass following nitrogen and potassium application HortScience 26 851 853
Chen, H., Park, B. & Murphy, J. 2014 Performance of fine fescues under two types of traffic. Proc. 2014 ASA Annu. Mtg. 289-7
Chen, H., Park, B.S. & Murphy, J.A. 2016 Performance of fine fescues under abrasive wear in different seasons. Proc. XXV Anniversary Rutgers Turfgrass Symp. 25:49–50
Cortese, L., Smith, D., Bara, R., Mohr, M., Weibel, N., Bonos, S.A. & Meyer, W. 2011 Performance of fine fescue cultivars and selections in New Jersey turf trials Rutgers Turfgrass Proc. 34 27 36
Cross, J., Koch, E., Smith, D., Mohr, M., Weibel, E., Bara, R., Bonos, S.A. & Meyer, W.A. 2013 Response of fine fescue turf species to simulated wear in New Jersey Intl. Turfgrass Soc. Res. J. 12 731 738
Dernoeden, P.H., Carroll, M.J. & Krouse, J.M. 1994 Mowing of three fescue species for low-maintenance turf sites Crop Sci. 34 6 1645 1649
Dowgiewicz, J.M. 2009 Inter-and intra-specific variation in wear mechanisms in Agrostis: I. Wear tolerance and recovery II. Anatomical, morphological and physiological characteristics. Univ. Mass., Amherst, MS Diss
Hamrick, K. Ecosystem Marketplace 2016 State of environmental investment in conservation 2016. Ecosystem Marketplace, Washington, D.C
Han, Y., Perdomo, P., Murphy, J.A., Meyer, W.A., Bonos, S.A., Dickson, W.K., Smith, D.A., Bara, R.F., Mohr, M. & Watkins, E. 2003 Performance of fine fescue cultivars and selections in New Jersey turf trials Rutgers Turfgrass Proc. 34 27 56
Horgan, B., Hollman, A., Koeritz, E. & Stier, J. 2007 Fine fescues and colonial bentgrasses for fairways Golf Course Mgt. 75 5 112 117
Huff, D.R. & Palazzo, A.J. 1998 Fine fescue species determination by laser flow cytometry Crop Sci. 38 2 445 450
Murphy, J.A. & Ebdon, J.S. 2013 Study and management of turfgrass traffic stress, p. 1029–1063. In: J.C. Stier, B.P. Horgan, and S.A. Bonos (eds.). Turfgrass: Biology, use, and management. Agron. Monogr. 56. ASA, CSSA, SSSA, Madison, WI
National Turfgrass Evaluation Program (NTEP) 2009a Mean turfgrass quality ratings of Kentucky bluegrasss cultivars grown under traffic stress at Madison, WI. National Turfgrass Evaluation Program, Beltslville, MD. 10 Mar. 2017. <http://www.ntep.org/data/>.
National Turfgrass Evaluation Program (NTEP) 2009b Mean turfgrass quality ratings of Kentucky bluegrasss cultivars grown under traffic stress at North Brunswick, NJ. National Turfgrass Evaluation Program, Beltslville, MD. 10 Mar. 2017. <http://www.ntep.org/data/>
Nyquist, W.E. & Baker, R. 1991 Estimation of heritability and prediction of selection response in plant populations Crit. Rev. Plant Sci. 10 3 235 322
Osmond, D.L. & Hardy, D.H. 2004 Characterization of turf practices in five North Carolina communities J. Environ. Qual. 33 2 565 575
Park, B.S., Chen, H. & Murphy, J.A. 2016 Comparing the Rutgers wear simulator, Cady traffic simulator, and Brinkman traffic simulator, p. 103–110. In: A. Gracie et al. (eds.). XXIX Intl. Hort. congress on Hort.: Sustaining lives, livelihoods and landscapes (IHC2014). Acta Hort. Press, Belgium
Park, B.S., Lawson, T.J., Samaranayake, H. & Murphy, J.A. 2010 Tolerance and recovery of Kentucky bluegrass subjected to seasonal wear Crop Sci. 50 4 1526 1536
Rummele, B.A., Wipff, J.K., Brilmann, L. & Hignight, K.W. 2003 Fine-leaved Festuca species, p. 129–164. In: M.D. Casler and R.R. Duncan (eds.) Turfgrass biology, genetics, and breeding. Wiley, Hoboken, NJ
Samaranayake, H., Lawson, T. & Murphy, J. 2008 Traffic stress effects on bentgrass putting green and fairway turf Crop Sci. 48 3 1193 1202
Shortell, R.R., Dickson, W.K., Smith, D.A., Bara, R.F., Wilson, M.M., Murphy, J.A., Bonos, S.A. & Meyer, W.A. 2005 Performance of fine fescue cultivars and selections in New Jersey turf trials Rutgers Turfgrass Proc. 37 35 37
Smith, D.A., Bara, R.F., Wilson, M.M., Weibel, E.N., Bonos, S.A. & Meyer, W.A. 2010 Performance of fine fescue cultivars and selections in New Jersey turf trials Rutgers Turfgrass Proc. 41 29 58
United States Department of Agriculture (USDA) 2012 National agricultural statistics survey. USDA, Washington, D.C. 13 Mar. 2017. <http://www.nass.usda.gov/>
Vanini, J.T., Henderson, J.J., Sorochan, J.C. & Rogers, J.N. 2007 Evaluating traffic stress by the Brinkman traffic simulator and Cady traffic simulator on a Kentucky bluegrass stand Crop Sci. 47 2 782 786
Watkins, E., Hollman, A.B. & Horgan, B.P. 2010 Evaluation of alternative turfgrass species for low-input golf course fairways HortScience 45 113 118
Yousef, E.A., Lampei, C. & Schmid, K.J. 2015 Evaluation of cauliflower genebank accessions under organic and conventional cultivation in Southern Germany Euphytica 201 3 389 400
Yue, C., Wang, J., Watkins, E., Bonos, S.A., Nelson, K.C., Murphy, J.A., Meyer, W.A. & Horgan, B.P. 2017 Heterogeneous consumer preferences for turfgrass attributes in the United States and Canada Can. J. Agr. Econ. 65 3 347 383
