Published online 22 January 2007
Published in Crop Sci 47:83-90 (2007)
© 2007 Crop Science Society of America
677 S. Segoe Rd., Madison, WI 53711 USA
TURFGRASS SCIENCE
Meadow Fescue and Tetraploid Perennial Ryegrass—Two New Species for Overseeding Dormant Bermudagrass Turf
M. D. Richardsona,*,
K. W. Hignightb,
R. H. Walkerc,
C. A. Rodgersd,
D. Rushb,
J. H. McCallaa and
D. E. Karchera
a Univ. of Arkansas, Fayetteville, AR 72701
b Advanta Seeds Pacific, Albany, OR 97322
c Auburn Univ., Auburn, AL 36849
d Seeds West Inc., Maricopa, AZ 85239
* Corresponding author (mricha{at}uark.edu)
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ABSTRACT
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Bermudagrass (Cynodon spp.) is often overseeded with a cool-season turfgrass to provide a green, actively growing surface for winter and early-spring sporting activities. Two grass species that have not been tested for overseeding include tetraploid (2n = 4x = 28) perennial ryegrass (Lolium perenne L.) and meadow fescue (Festuca pratensis Huds.). The objectives of this study were to test these two species in comparison to three standard overseeding species [diploid perennial ryegrass, intermediate ryegrass (L. perenne x L. multiflorum Lam.), and Poa trivialis L.] in three environments; Maricopa, AZ (arid), Fayetteville, AR (transition zone), and Auburn, AL (humid, subtropical). At all locations, overseeding grasses were seeded into dormant bermudagrass turf and managed according to standard overseeding practices. The tetraploid ryegrass had equal or superior turfgrass quality to all other overseeding species except the diploid ryegrass. Meadow fescue produced similar turfgrass quality to intermediate ryegrass and tetraploid ryegrass at Arkansas and Alabama, but had lower turf quality scores in Arizona. The meadow fescue and tetraploid ryegrass transitioned more quickly back to bermudagrass compared to the diploid ryegrass, intermediate ryegrass, and P. trivialis, which would be very favorable aspects of these new overseeding grasses. These trials clearly demonstrate the potential of two new species, meadow fescue and tetraploid ryegrass, for overseeding dormant bermudagrass turf.
Abbreviations: DGCI, dark green color index • HSB, hue angle, saturation, and brightness
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INTRODUCTION
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BERMUDAGRASS CONTINUES to be the predominate turfgrass species used for golf courses and sports fields in tropical and transition zone areas of the world. Although bermudagrass has many positive attributes, such as good wear tolerance and recuperative potential, excellent heat and drought stress tolerance, and broad pest resistance, the species experiences a long winter dormancy period in many use areas. Because of this extended dormancy period, bermudagrass is often overseeded with a cool-season turfgrass to provide an actively growing green surface for winter and early-spring sporting activities (Dudeck and Peacock, 1980; Schmidt and Shoulders, 1977).
Successful overseeding programs are affected by a number of management decisions, such as propagation techniques, fertilizer and water management, mowing practices, and pest management (Horgan and Yelverton, 2001; Johnson, 1976; Kneebone and Major, 1969; Mazur and Wagner, 1987; Mazur and Rice, 1999). However, one of the most important decisions in an overseeding program is the selection of an appropriate cool-season species for a specific application. A wide range of grasses has been successfully used for overseeding, including annual (Italian) ryegrass (L. multiflorum), perennial ryegrass, intermediate ryegrass, creeping bentgrass (Agrostis stolonifera L.), rough bluegrass (P. trivialis), and fine fescue (Festuca spp.) (Kneebone and Major, 1969; Ward et al., 1974; Schmidt and Shoulders, 1977; Richardson, 2004). Annual ryegrass was one of the first species used for overseeding (Kneebone and Major, 1969) due to its rapid germination and establishment, but this species generally has poor density and texture and requires frequent mowing due to a rapid growth rate (Richardson, 2004). Creeping bentgrass and rough bluegrass have been used for overseeding in niche areas such as closely mowed putting greens (Ward et al., 1974), but have not been well accepted for overseeding use on golf course fairways and tees and sports fields.
Perennial ryegrass is the most widely used species for overseeding dormant bermudagrass and is especially popular in higher-cut turf such as golf fairways and sports fields (Schmidt and Shoulders, 1977). However, increases in heat tolerance, drought tolerance, and disease resistance of improved cultivars have made perennial ryegrass a problematic weed following overseeding because it is very persistent and does not behave as an annual in southern climates (Horgan and Yelverton, 2001). The persistence of perennial ryegrass has increased the use of alternative species such as intermediate ryegrass (Schmitz, 1999; Richardson, 2004). Intermediate ryegrass is an interspecific hybrid between annual and perennial ryegrass and has been used as an overseeding species. Intermediate ryegrass cultivars have been documented to have better transition characteristics compared to perennial ryegrass (Richardson, 2004).
Although there are numerous cool-season grasses that have been tested for overseeding dormant turf, there is a continued need to develop new species and cultivars with applications to overseeding situations. In recent years, there have been efforts to improve turfgrass characteristics of both meadow fescue and tetraploid ryegrass, species that have been used in various forage systems around the world but have received minimal interest from the turfgrass industry.
Meadow fescue was first introduced into North America in early colonial times (Kennedy, 1900), but its use as a forage grass was minimal compared to related grasses such as tall fescue [F. arundinaceae (L.) Schreb.], orchardgrass (Dactylis glomerata L.), and perennial ryegrass. However, meadow fescue has been used extensively as a germplasm source in the development of interspecific hybrids with both perennial and annual ryegrass (Thomas and Humphreys, 1991). There has also been recent interest in using this species in intensively managed grazing systems and breeding efforts might enhance its use as a forage grass (Casler and van Santen, 2001). Meadow fescue has not been tested extensively as an amenity grass, although early trials at Aberystwyth, Wales, suggested that meadow fescue had limited potential as a turfgrass, producing a thin, open sward that competed poorly with weedy grasses such as P. annua (Handoll, 1966; Fisher, 1951).
Perennial ryegrass is one of the most widely used species for overseeding dormant bermudagrass and all major turfgrass cultivars are natural diploids (2n = 2x = 14). This species has been dramatically improved through traditional breeding techniques for characteristics such as color, density, mowing quality, and disease resistance. In forage breeding programs, chromosome doubling techniques have been widely employed to create tetraploid lines of perennial ryegrass (2n = 4x = 28) with improved vigor, enhanced biomass production, and improved forage quality (Warnock et al., 2005; Sanderson and Elwinger, 2004; Jensen et al., 2003; Smith et al., 2001). However, we are not aware of tetraploid cultivars being tested in turfgrass systems to date.
Recent efforts to improve turfgrass quality characteristics of both meadow fescue and tetraploid ryegrass have resulted in new germplasm of both species that may have potential in turfgrass systems. The objective of this study was to investigate the use of a meadow fescue and tetraploid ryegrass in an overseeding system in three diverse environments, including the southeastern United States, the transition zone, and the desert Southwest.
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MATERIALS AND METHODS
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Plant Material and Seeding Rates
Five overseeding treatments were tested at each of three locations, including Maricopa, AZ (33°26' N, 112°1' W), Auburn, AL (32°36' N, 85°30' W), and Fayetteville, AR (36°0' N, 94°10' W). The entries included diploid perennial ryegrass (cv. Integra, Pennington Seed, Madison, GA), tetraploid perennial ryegrass (Expt. T3, Advanta Seeds Pacific, Albany, OR, patent pending), intermediate ryegrass (50% Transist and 50% Transeze, Pickseed West, Albany, OR), meadow fescue (Expt. MF29, Advanta Seeds Pacific, Albany, OR, patent pending), rough bluegrass (cv. PT-109, Pennington Seed), and a nonseeded control. Seed counts and germination tests were conducted on all species and all seeding rates were adjusted to deliver 2.37 pure live seeds cm–2. Overseeding entries were established in an existing bermudagrass sward maintained under simulated fairway conditions, with mowing at a height of 1.9 cm. The bermudagrass cultivars used at each site included Tifsport (C. dactylon x C. transvaalensis Burtt Davy) at Alabama, Princess-77 [C. dactylon (L.) Pers. var. dactylon] at Arizona, and Riviera [C. dactylon (L.) Pers. var. dactylon] at Arkansas. Plot size was 1.8 by 4.6 m and each overseeding entry was replicated four times at each location in a randomized complete block design.
Management Practices
Although seeding methods were identical at each location, each site adopted management practices that were typical in their region for overseeding turf. At each location, irrigation was applied two to three times per day during the germination period to maintain adequate soil moisture for seed germination. After establishment of the plots, irrigation was applied three times per week in the absence of natural rainfall. Specific management factors at each site were as follows.
Maricopa, Arizona
This study was located at the Seeds West Inc. research facility in Pinal County, Arizona. The soil type was a Casa Grande clay loam (fine-loamy, mixed, superactive, hyperthermic Typic Natrargid) with an average pH of 7.8. Before seeding plots on 8 Oct. 2004, the bermudagrass was dethatched in two directions with a vertical mower and scalped to a height of 1.2 cm and the soil was amended with 220 kg S ha–1 and 44 kg P ha–1. Following establishment, plots were mowed three times per week with a reel mower set to a height of 1.2 cm with clippings removed. Once mowing began, plots were fertilized with urea (46–0–0) at a rate of 49.0 kg N ha–1 per growing month.
Auburn, Alabama
This study was located at the Auburn University Turfgrass Research Unit in Lee County, Alabama. The soil type was a Marvyn loamy sand (fine, mixed mesic Typic Paleudult) with an average pH of 6.0. Before seeding plots on 25 Oct. 2004, the bermudagrass was dethatched in two directions with a vertical mower and scalped to a height of 1.2 cm. Following establishment, plots were mowed three times per week with a reel mower set to a height of 1.9 cm with clippings returned. Once mowing began, plots were fertilized with 41–0–0 (Polyon, Pursell Technologies Inc., Sylacauga, AL) at a rate of 74.0 kg N ha–1 in both November and January and with urea (46–0–0) at a rate of 49.0 kg N ha–1 per month in March and April. In addition, iprodione [3-(3,5-dichlorophenyl)-N-isopropyl-2,4-dioxoimidazolidine-1-carboxamide] was applied at 0.48 kg a.i. ha–1 in January 2005.
Fayetteville, Arkansas
This study was located at the University of Arkansas Research and Extension Center in Washington County, Arkansas. The soil type was a Captina silt loam (fine-silty, siliceous, active, mesic Typic Fragiudult) with an average pH of 6.2. Before seeding plots on 7 Oct. 2004, the bermudagrass was dethatched in two directions with a vertical mower and scalped to a height of 1.2 cm and the soil was amended with 44 kg P ha–1. Following establishment, plots were mowed three times per week with a reel mower set to a height of 1.2 cm with clippings returned. Once mowing began, plots were fertilized with urea (46–0–0) at a rate of 49.0 kg N ha–1 per growing month.
Data Collection
Establishment of overseeded grasses was measured as either seedling vigor (1–9 scale, with 1 = no germination and 9 = full germination) at 14 d after planting or visual estimates of percent stand of the overseeded grass at 6 wk after planting. Turfgrass performance was visually assessed each month during the overseeding season (November–June) as turfgrass color (1–9 with 9 = dark green color) and turfgrass quality (1–9 with 9 = optimal turfgrass quality). For both turfgrass color and quality, data were pooled across rating dates to yield seasonal performance measures. For turfgrass color, ratings taken in December, January, or February were considered winter color ratings and combined in a single average, while data collected in March, April, and May were combined to give a spring color average. Turfgrass quality data was also averaged across rating dates to yield an average turfgrass quality for winter (November, December, and January), early spring (February, March, and April), and late spring (May and June). In addition, a turfgrass quality average was computed for each entry over the entire experimental period.
Turfgrass color was also measured quantitatively at the Arkansas site using digital image analysis procedures (Karcher and Richardson, 2003). Digital images were collected from the plots using a uniform light source (Ikemura, 2003) and analyzed using commercially available software (SigmaScan Pro version 5.0, SPSS, Chicago, IL). Average red, green, and blue levels were determined for each image and then converted into hue angle, saturation, and brightness (HSB). The HSB values were used to generate a measure of turfgrass color, described as the dark green color index (DGCI) (Karcher and Richardson, 2003).
Transition of overseeded cool-season grass back to bermudagrass was visually rated biweekly beginning at the initiation of spring green-up in the nonseeded control and was recorded as percentage bermudagrass in the plot. Several rating dates were pooled at each site for transition estimates to yield an early-, mid-, and late-transition period estimate at each location. Transition back to bermudagrass was not aided with chemical or cultural practices.
At two sites (Alabama and Arkansas), clipping yields were determined three times during the spring, when the overseeded grasses were at a peak growth rate. Two passes were made down the length of each plot with a walking greens mower set to a bench height of either 1.2 cm (Arkansas) or 1.9 cm (Alabama) and the clippings collected. Clippings were dried in a forced-air oven at 70°C for 48 h and the dry weight of clippings determined.
At the Arkansas and Alabama site, a significant amount of the overseeded, cool-season grass persisted through the summer period and was present in the plots the following autumn and winter. Persistence was evaluated at the Arkansas site using digital image analysis (Richardson et al., 2001) to measure cool-season grass (%) in the plot following dormancy of the bermudagrass in the autumn of 2005. Three digital images were collected from each plot and the amount of green overseeded turf was measured using image analysis and the three subsamples were averaged for each plot. At the Alabama site, persistence was measured as a visual estimate of percentage of cool-season grass in plots following dormancy of the bermudagrass.
All data were analyzed using analysis of variance procedures, testing the main effects of location and entry and their interaction. A significant location x entry interaction was observed for all data collected, so data could not be pooled across locations for analysis. Means were separated using Fisher's protected least significant difference (LSD, 
= 0.05).
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RESULTS AND DISCUSSION
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Successful overseeding depends on many factors, including rate of establishment, turfgrass performance, management issues, and the spring transition from overseeded cool-season grass back to bermudagrass. All species tested in this trial germinated within 7 d of sowing at all locations (data not shown), but the ryegrass entries generally had the greatest seedling vigor (Table 1). There were no significant differences in seedling vigor between diploid, tetraploid, or intermediate ryegrass at any location (Table 1). Earlier work on germination and seedling vigor of tetraploid ryegrasses has been inconclusive, with some studies showing improved vigor of tetraploids due to increased seed size (Norrington-Davies and Harries, 1977). However, recent studies by Sanderson and Elwinger, 2004, found no relationship between increased seed size in tetraploid and increased seedling vigor, which concurs with the present study (Table 1).
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Table 1. Establishment vigor of various overseeding grasses as measured by germination vigor at 14 d after planting (DAP) and percentage of overseeding grass cover at 6 wk after planting (WAP).
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Seedling vigor for meadow fescue was intermediate between the ryegrasses and P. trivialis at both Arizona and Arkansas but was equal to the ryegrasses at Alabama (Table 1). This is the first comparative report on seedling vigor and establishment between meadow fescue and perennial ryegrass and the species appears to establish at a satisfactory rate compared to the other species tested. The P. trivialis had the weakest seedling vigor at all locations (Table 1). Stand establishment followed a similar trend to seedling vigor, with the ryegrass entries producing the greatest stand at 6 wk after planting and P. trivialis producing the least cover (Table 1). The intermediate ryegrass was the only species that consistently produced the highest turfgrass coverage at all three locations (Table 1), similar to earlier results which compared intermediate cultivars to diploid perennial ryegrass cultivars (Richardson, 2004).
For overseeding grasses, turfgrass quality is primarily a function of turfgrass density, uniformity, mowing quality, texture, and color (Schmidt and Shoulders, 1977). When averaged across the entire growing season, the diploid perennial ryegrass produced the highest turfgrass quality at all locations but was not statistically different from the intermediate or tetraploid ryegrass at Alabama (Table 2). The tetraploid ryegrass also performed favorably and was equal or superior to all other overseeding species except the diploid ryegrass at all locations (Table 2, Fig. 1
). This is a significant observation, since this is the first known report of a tetraploid ryegrass being used to overseed a dormant bermudagrass turf and this species produced good turfgrass quality compared to both perennial ryegrass and intermediate ryegrass.
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Table 2. Turfgrass quality of various overseeding grasses at three locations. Data were compiled from multiple month ratings to yield a composite score for winter (November, December, and January), early spring (February, March, and April), late spring (May and June), and a seasonal average (November–June).
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Fig. 1. General turfgrass quality and color of four overseeding grasses at Fayetteville, AR, including (A) diploid perennial ryegrass, (B) tetraploid perennial ryegrass, (C) intermediate ryegrass, and (D) meadow fescue. Photos were taken on 11 May 2005 with natural lighting.
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Under the management conditions of these trials, P. trivialis produced the lowest seasonal turfgrass quality at all three locations but was not statistically different from the meadow fescue at Arizona and Alabama. Poa trivialis is primarily used to overseed closely mown turf such as bermudagrass putting greens and its performance at the higher mowing heights used in this study was inferior to the ryegrasses. In a recent, multisite overseeding trial on golf course fairways, P. trivialis was inferior to perennial ryegrass entries at all but two sites and was not considered the optimum turfgrass species for fairway overseeding (Morris, 2004).
Meadow fescue produced similar turfgrass quality to intermediate ryegrass and tetraploid ryegrass in Arkansas, but had lower turf quality scores in Alabama and Arizona (Table 2, Fig. 1). Meadow fescue did not perform as well as other overseeded species in AZ due to coarser leaf texture (data not shown) and a lighter green color (Table 3). However, the turfgrass quality observed in this trial suggests that the species has potential as an overseeding grass and further research is warranted. When analyzed by season (winter, early spring, and late spring), similar trends in turfgrass quality were observed at all locations, with the diploid ryegrass generally producing the highest turfgrass quality and the meadow fescue and P. trivialis producing the least favorable turfgrass quality (Table 2).
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Table 3. Turfgrass color of various overseeding grasses at three locations. Data were compiled from multiple month ratings to yield a composite score for winter (December, January, and February) and spring (March, April, and May).
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A major component of the turfgrass quality ratings were differences in turfgrass color. Across all three locations, the diploid and tetraploid ryegrasses produced the highest turfgrass color in both the winter and spring seasons (Table 3). The meadow fescue, intermediate ryegrass, and P. trivialis produced similar color ratings at all locations in both seasons (Table 3). Digital image analysis was used to more accurately quantify the color of the various overseeding species at the Arkansas site. Significant differences between overseeding species were observed for HSB and DGCI (Table 4). Interestingly, all overseeding species except the intermediate ryegrass had similar hue angle values (Table 4), even though there were significant differences in visual turfgrass color ratings (Table 3) and DGCI (Table 4). The overseeding grasses that exhibited the darkest subjective color ratings (Table 3) also had the highest DGCI (Table 4). However, these grasses had the lowest saturation and brightness values compared to other species.
Clipping yields were collected at two locations in this trial to assess the growth characteristics of these new grasses relative to standard grasses such as diploid perennial ryegrass and intermediate ryegrass. Earlier research demonstrated that intermediate ryegrass and annual ryegrass had accelerated growth characteristics compared to perennial ryegrass, a factor that could add to the maintenance cost of these species (Richardson, 2004). At Arkansas, the meadow fescue had the highest clipping production across the three sampling dates and the diploid perennial ryegrass and P. trivialis had the lowest (Table 5). However, at Alabama, the only species that had statistically different clipping yields were the tetraploid ryegrass and intermediate ryegrass, with the tetraploid having lower clipping yields than the intermediate. These data suggest that tetraploid ryegrass will not have significantly higher mowing requirements than other overseeding species.
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Table 5. Clipping yields of various overseeding grasses as determined on three dates at two locations. Clippings are reported on a dry matter basis.
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The spring transition of an overseeded grass back to the base bermudagrass can be one of the more challenging aspects of overseeding management, especially since new cultivars of perennial ryegrass generally have good heat, drought, and disease resistance and tend to persist much longer into the summer (Mazur and Wagner, 1987). At each location, there were significant differences in transition due to the overseeded species (Table 6). At Arizona, the meadow fescue began to transition sooner than other species during the early and mid-transition period, but was not different from P. trivialis by the late evaluation period (Table 6). The diploid perennial ryegrass was the slowest to transition at this site. The tetraploid ryegrass was intermediate to other species at all rating dates and was similar to the intermediate ryegrass at the early and late transition dates (Table 6). At the Arkansas site, intermediate ryegrass, tetraploid ryegrass, and meadow fescue all had better transition back to bermudagrass than diploid perennial ryegrass and P. trivialis (Table 6). Similar to Arizona, the diploid perennial ryegrass was the slowest to transition back to the base bermudagrass. At the Alabama site, P. trivialis was the slowest to transition back to bermudagrass and the other species produced similar transition responses (Table 6).
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Table 6. Emergence of bermudagrass in overseeded plots during the spring transition period. Data from a minimum of two rating periods were combined to give the composite score.
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A final component of transition is the persistence of the overseeding grass the autumn following the summer transition period, which can lead to significant weed problems if overseeding is not continued the next season. As a measure of summer survival, plots at Alabama and Arkansas were monitored for overseeding recovery the following autumn after the bermudagrass had gone into dormancy. At the Arkansas site, which is an upper transition zone location, significant survival was observed with all species, but the P. trivialis had greater survival compared to the meadow fescue and the tetraploid ryegrass (Fig. 2
. The tetraploid ryegrass had the lowest survival of all species tested, indicating the most complete transition back to the bermudagrass (Fig. 3
). At the Alabama location, there was minimal survival of the P. trivialis and meadow fescue and these were not statistically different from the diploid ryegrass and the tetraploid ryegrass. The intermediate ryegrass had higher survival than the P. trivialis at this location. It is interesting that P. trivialis was one of the poorest performing overseeding grasses relative to transition at all locations, as this grass is typically described as having less heat tolerance and better transition characteristics than perennial ryegrass (Morris, 2004).
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Fig. 2. Survival of overseeded, cool-season grasses as measured in the second winter following seeding. Data was collected after bermudagrass went into winter dormancy. Within each location, means sharing either an uppercase (Arkansas) or lowercase (Alabama) letter are not statistically different according to Fisher's protected LSD ( = 0.05).
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Fig. 3. Survival of overseeded, cool-season grasses at Fayetteville, AR, in the second winter following seeding. Photos were taken on 15 Dec. 2005 under natural lighting and include (A) diploid perennial ryegrass, (B) tetraploid perennial ryegrass, (C) intermediate ryegrass, and (D) meadow fescue.
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In summary, these trials clearly demonstrate the potential of two new species, meadow fescue and tetraploid ryegrass, for overseeding dormant bermudagrass turf. As these are the first experimental lines developed for this purpose, it is assumed that further advances can be made by breeders to enhance desirable characteristics in these species. At present, the most notable characteristics displayed by these species include good germination and seedling vigor, good turfgrass color and quality, and improved transition characteristics compared to diploid perennial ryegrass. Future studies should focus on the specific management requirements for these species such as optimal seeding rates, fertility requirements, mowing requirements, and pest management issues.
Received for publication April 5, 2006.
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REFERENCES
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ABSTRACT
INTRODUCTION
