Crop Science 40:1339-1343 (2000)
© 2000 Crop Science Society of America
TURFGRASS SCIENCE
Low-Mowing Tolerance in Buffalograss
P.G. Johnsona,c,
T.P. Riordanb and
J. Johnson-Cicalesec
a Dep. of Plants, Soils, and Biometeorology, 4820 Old Main Hill, Logan, UT 84322-4820 USA
b Dep. of Horticulture, 377 Plant Sciences, Univ. of Nebraska, Lincoln, NE 68583-0724 USA
c Plant Science, Rutgers University, 76 Lipman Drive, New Brunswick, NJ 08901 USA
pjohnson{at}mendel.usu.edu
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ABSTRACT
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Drought-tolerant turfgrasses that can tolerate low mowing heights need to be identified in order to obtain reduction in water use required of turfgrass in many locations. We have begun evaluation and selection of buffalograss [Buchloë dactyloides (Nutt.) Engelm.] at typical golf course fairway mowing heights. A large number of accessions originating from throughout the Great Plains of North America, with the majority from the northern Plains, are being maintained at 1.6-cm mowing heights. Seedlings from a polycross of six females and four males provided six half-sib families to observe under similar conditions. Turfgrass quality and genetic color differed significantly among entries in the trials. Several vegetatively propagated genotypes yielded high-quality turf and exhibited vigorous and competitive growth under low mowing. When data were analyzed by gender, female genotypes performed better than male or monecious types. Genotypes marginally hardy in Nebraska were not hardy when maintained at low mowing heights. Seeded varieties performed well for fall color, probably because of greater genetic diversity. Preliminary selection may be accomplished at higher mowing heights prior to the more costly and time-consuming low-mowing evaluations. Results indicate that low-mowing tolerance may be heritable in buffalograss.
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INTRODUCTION
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AS WATER DEMANDS increase throughout the world, turfgrass breeders have responded by initiating a number of breeding programs to develop low-maintenance, drought-tolerant turfgrasses. Buffalograss has been the subject of substantial breeding work in the past 15 yr, primarily because of its tolerance of heat and drought stress and potential for good turfgrass quality (Riordan et al., 1993). Buffalograss is native to the harsh conditions of the western Great Plains of North America from Mexico to southern Canada (Beetle, 1950). Numerous varieties have been developed with improved turfgrass characteristics; however, the use of buffalograss has been limited by the perceived need for high mowing heights and lack of fine turfgrass quality. Because buffalograss is considered a low-maintenance grass, turf managers have not used the species extensively, except in so-called no-mow areas, ornamental plantings, and low-maintenance lawns. To obtain the kind of water-use reduction required in many locations, buffalograss may need to be used in a greater proportion of the landscape, including golf courses.
One stress to overcome on the golf course is tolerance to lower mowing heights, specifically those required by golf course managers for use on golf course fairways. Fairways are mowed at <3 cm, much lower than the 
8 cm usually considered optimum for buffalograss. Low mowing heights stress the turfgrass plant, primarily because of the reduction of photosynthetic area. Buffalograss exhibits a prostrate growth habit with vigorous stolons similar to the low-mowing tolerant species creeping bentgrass (Agrostis palustris Huds.) and bermudagrass (Cynodon dactylon L.).
This study demonstrates the use of buffalograss in closely mowed turf, variation in buffalograss germplasm for tolerance to low-mowing, and potential for selection of tolerance to low mowing heights.
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Materials and methods
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Data presented here are from three field plantings and one crossing block. All plantings were located at the John Seaton Anderson Turfgrass and Ornamental Research Facility, on the Agricultural Research and Development Center, located near Mead, NE. The soil is a Sharpsburg silty clay loam (fine, smectitic, mesic Typic Argiudoll).
Area 1
Area 1 was established during summer of 1990 and included 97 vegetatively established entries and one seed-established entry. Each plot was 1.5 by 1.5 m, replicated three times in a randomized complete block design. Seeded plots were established using 146 kg ha-1 of burs. Vegetatively planted plots were established with 12 plugs, each 7.6 cm in diameter, spaced on 
38-cm centers. The accessions in Area 1 were a collection from throughout the North American Great Plains region, with the majority from Kansas, Nebraska, and Colorado. Supplemental irrigation was supplied only during the establishment phase (1990). The trial area was mowed at 7.6 cm twice monthly during 1990 to 1991. Mowing height was gradually lowered in 1992, over two months, to 1.6 cm and maintained at that height through 1995. Mowing frequency at the low height was one time per week in late spring and late summer and twice per week during summer. Pesticide applications included yearly treatments near the end of April with pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzeneamine] and occasional spot treatments with glyphosate [N-(phosphonomethyl) glycine], when the buffalograss was dormant (October–March). Area 1 was fertilized with 146 kg ha-1 N yr-1 applied as Milorganite (6-2-0; Milwaukee Metropolitan Sewerage District, Milwaukee, WI). Applications were split among June, July, and August. Turfgrass quality, color, and density ratings, based on a 1 to 9 scale where 1 is dead and 9 is ideal, were taken monthly during the growing season. Color ratings in late September to mid October determined fall color or earliness of dormancy.
Area 2
Area 2 included 21 seeded and 53 vegetative entries established in 1993. Area 2 was mowed at 7.6 cm until 1995. During 1996, the height was gradually lowered over 2 mo to 1.6 cm. All other plot design, accession origin, maintenance, and establishment parameters were similar to Area 1. For seeded plots, the burs were pretreated to break seed dormancy by soaking in 0.1% (w/w) KNO3 for 48 h, draining off free solution, then storing at 4°C for 4 wk. Burs were then air-dried and prepared for planting.
Crossing Block
A crossing block was established with genotypes from Area 1 for genetic recombination. Six females and four males were selected because of superior performance under low-mowing conditions. These were planted in a randomized block design with four replications. Plots were 1.8 by 1.8 m and established in 1994 with 20 vegetative plugs per plot. Burs were harvested in summer of 1995 from each female parent.
Area 3
Area 3 was established in 1996 with progeny of the crossing block. Caryopses were removed from the burs using a barley pearler (model 17810, Strong & Scott, Chicago, IL) and planted in conetainers (25 cm deep and 6.4 cm in diameter, with a volume of 656 mL; Stuewe & Sons, Corvallis, OR) in the greenhouse in January 1996. The soil mix was 33% peat, 33% perlite, and 33% silt loam soil. The temperature was maintained at 26°C days and 18°C nights with an 18-h photoperiod. The plants were fertilized by drenching pots every 2 wk with 200 mg L-1 N solution using a 20-10-20 fertilizer. Seedlings were transplanted to the field in May 1996. The plot area consisted of six half-sib families with 10 plants per row. Rows were 91 cm apart in a randomized complete block design with four replications of each family. Low mowing began in late July and plot maintenance thereafter was similar to Areas 1 and 2. Quality ratings and morphological measurements of plant width (diameter of plant at tips of stolons), length of second internode, and number of leaves on second internode were made during 1997. An adjacent area included seed-established plots with bulked seed from each maternal parent. These plots were broadcast seeded in May 1996, then managed the same as the individual plant populations.
Statistical Analysis
All analyses were done using SAS for Windows 6.12. We used PROC GLM for all analysis of variance tests and Fischer's protected LSD for mean separation at the 0.05 level. When missing data were present, least squares means and t tests were used for individual comparisons (LSMEANS and TDIFF option). To test for significant variation between families in Area 3, we subjected the absolute value of residuals from analysis of variance of turfgrass quality measurements to analysis of variance themselves. PROC CORR was used for correlation analysis. The variance component method was used to estimate heritability of traits on an entry-mean basis.
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Results and discussion
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Area 1
Turfgrass quality and genetic color differed significantly among entries in Area 1. Several vegetatively propagated genotypes yielded high-quality turf and exhibited vigorous and competitive growth under low-mowing, especially 86-61, 86-120, and 84-315 (Table 1)
. These genotypes, especially 86-61, encroached upon lesser-adapted genotypes and spread into an area greater than twice the size of the original plot. The higher density of vegetatively propagated, or clonal, cultivars was important in this improved turfgrass quality (Riordan et al., 1993).
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Table 1 Area 1 mean turfgrass quality, mean color ratings, and gender of a subset of buffalograss genotypes under low-mowing conditions, from 1992 to 1995
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The seeded plot, `Texoka', did not tolerate low-mowing conditions (Table 1). This cultivar is a forage type and not adapted to turfgrass conditions at such low mowing heights. Many plots had low ratings due to substantial low-temperature injury. In evaluations at higher mowing heights, many of these same genotypes (i.e., 84-609) recovered from winter damage (data not presented) and did not die out completely. The stress of low mowing heights plus low temperatures is too severe for these genotypes in the northern regions. Low-mowing evaluations in southern regions would be a better test of these southern-adapted genotypes.
The average performance of all plots in this trial was quite high in overall plot appearance and indicated generally good low-mowing tolerance in a broad range of buffalograss accessions. Genetic color ratings were correlated with turfgrass quality (Fig. 1)
. Density and turfgrass quality showed a very similar association (
; P < 0.0001).
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Fig. 1 Scatter plot of average turf quality in 1992 to 1995 vs. genetic color averages in 1992 to 1995. Data are from Area 1
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When Area 1 data were analyzed by gender, mean turfgrass quality for female genotypes was 5.3 (on a 1–9 scale), which was significantly better (P < 0.05) than males or monecious types, both of which exhibited a 5.0 mean turfgrass quality. Female buffalograss genotypes often exhibit better turfgrass quality than males because their flowers are hidden within the canopy and are the same color as the leaves. Male flowers are produced above the leaf canopy with anther colors ranging from yellow to purple. Otherwise, males and females are morphologically identical.
Area 2
In Area 2, several genotypes had high turfgrass quality ratings, especially 92-135 (Table 2)
. Area 2 included 21 seed-established populations derived from male and female genotypes specifically selected for improved turfgrass quality (Klingenberg, 1992). Significant improvements are evident compared with the forage varieties Texoka and Sharps Improved (Table 2).
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Table 2 Area 2 mean turfgrass quality and mean fall color ratings for a subset of buffalograss genotypes at two mowing heights
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No overall gender differences were observed for turfgrass quality. The performance of male plants showed the opportunity for additional selection of male parents for use in seeded varieties. However, female genotypes dominated among the top performers (Table 2). Only one male and two seeded varieties appeared in the top ten for turfgrass quality. The unbalanced data set (unequal numbers of males and females) and variation within genders may explain why overall means were not significant.
Fall color performance yielded opposite rankings compared with summer turfgrass quality, as indicated by a negative Spearman rank correlation (-0.15; P < 0.05). Most top-performing entries for quality (during summer) had poor fall color (Table 2). Genotypes in Area 2 are northern types (adapted to the northern Great Plains) and go dormant early in fall for maximum winter hardiness. Southern-adapted genotypes like 84-609 and 91-118 have excellent fall color, but reduced quality ratings because of winter injury. Genotype 91-118 provided excellent turf quality in Nebraska and was not affected by winter temperatures in most years when mowed at 8+ cm (Riordan et al., 2000). However, under low-mowing conditions, there was significant winterkill in this genotype.
If buffalograss is to be mowed below 2.5 cm in the northern United States and Canada, genotypes must be well adapted to that environment. Genotype 91-118 would be expected to tolerate low mowing south of Nebraska, or in areas with even slightly warmer winters. Tests of 91-118 mowed at 2.5 cm in Logan, UT, showed no winter injury effects (Kevin Frank, 1998, personal communication). Seeded varieties performed well for fall color (Table 2), even those adapted to northern regions, probably because of their greater genetic diversity.
In most cases, top-ranking genotypes in Area 2 also excelled when mowed at higher heights. Genotypes 86-120, 86-61, and 315 had been selected for cultivar development prior to low-mowing evaluations (Riordan et al., 1995; Johnson et al., 2000; Johnson-Cicalese et al., 2000). In addition, 92-135 in Area 2 exhibited high ratings prior to low-mowing evaluation (Table 2). Therefore, preliminary selection may be made at higher mowing heights prior to the more costly and time-consuming low-mowing evaluations.
Area 3
Low-mowing tolerance appears to be inherited in buffalograss. In general, maternal parents that exhibited exceptional turfgrass quality at low mowing heights, produced exceptional performing progeny. Genotype 86-61, the highest quality genotype in Area 1 (Table 1) and other tests (Johnson et al., 2000), yielded progeny that gave the highest mean for turfgrass quality (Table 3) . Genotype 85-648 is an exception. Although having a lower turfgrass quality average than other maternal parents in this evaluation (Table 1), 85-648 produced progeny with a quality mean equal to 86-61 (Table 3). Bulk-seeded plots from each female parent yielded no significant differences. The estimate of heritability for turfgrass quality, based on the one year's data available, is 0.89. Turfgrass quality has been shown to be heritable in buffalograss (Klingenberg, 1992; Browning et al., 1994), but additional experiments must be performed to obtain accurate estimates for low-mowing characteristics.
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Table 3 Area 3 population means of turfgrass quality and morphological data for progeny from polycross of buffalograss parents selected for low-mowing tolerance
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Morphological data on plants in Area 3 were recorded in an attempt to quantify characteristics that are correlated with low-mowing tolerance. Plant width, or spread, was significantly correlated with turfgrass quality under low mowing (
; P < 0.0001). Density was associated with low-mowing tolerance, as observed in Areas 1 and 2, but density apparently was not influenced by node spacing on the spreading stolons. Internode length showed no relationships
. Neither was leaf number per node correlated with turfgrass quality
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In addition to differences in turfgrass quality, families differed significantly in variation among progeny (Table 4)
. Parent genotypes 84-443 and 86-23 (Fig. 2)
were the most variable, while 86-120 and 85-648 (Fig. 2) were least variable. This variation among progenies of the maternal parents did not significantly affect analysis of variance for means. Therefore, turfgrass quality data were not transformed. Within-family variation is important in two ways. First, within-family variation is helpful in developing seeded varieties tolerant to low-mowing because parent genotypes that produce less variable progeny are most desirable. Second, variation in some families indicates additional potential for selection and is a good indication of complex genetics governing the low-mowing tolerance trait.
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Fig. 2 Histograms of turfgrass quality ratings under low-mowing for progenies of six half-sib families evaluated in Area 3 in 1997
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These evaluations indicate significant genetic potential for developing buffalograss cultivars to be used as a fairway turf in semiarid and arid regions, especially where water supplies are limiting or irrigation is cost prohibitive. While turfgrass quality is not equal to irrigated creeping bentgrass, perennial ryegrass (Lolium perenne L.), and Kentucky bluegrass (Poa pratensis L.), quality is acceptable considering the lack of irrigation inputs. An important trait needed if buffalograss is to be successfully used in low-mowing turfgrass situations is recuperative ability following traffic. Preliminary tests of traffic simulation and divoting of buffalograss mowed at 1.6 cm have indicated good recovery potential (data not presented). Environmental and management conditions, especially nutrition and water status of the turf, will be important to enhance traffic tolerance or recovery.
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NOTES
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Research was partially funded by the United States Golf Association. Utah Agricultural Experiment Station, Utah State University. Approved as Publication no. 7190.
Received for publication August 16, 1999.
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REFERENCES
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- Beetle, A.A. 1950. Buffalograss—Native of the short grass plains. Univ. of Wyo. Agric. Exp. Stn. Bull. 293. Laramie, WY.
- Browning S.J., Riordan T.P., Johnson R.K., Johnson-Cicalese J. Heritability estimates of turf-type characteristics in buffalograss. HortScience 1994;29:204-205.[Abstract/Free Full Text]
- Johnson P.G., Riordan T.P., Gaussoin R.E., Shearman R.C., Johnson-Cicalese J., Baxendale F.B., Klucas R.V. Registration of `61' buffalograss. Crop Sci. 2000;40:569-570.
- Johnson-Cicalese J., Johnson P.G., Riordan T.P., Gaussoin R.E., Baxendale F.B., Watkins J., Klucas R.V. Registration of `120' buffalograss. Crop Sci. 2000;40:571-572.
- Klingenberg, J.P. 1992. Evaluation, genetic variation, and selection for improvement of a seeded, turf-type buffalograss population (Buchloe dactyloides [Nutt.] Engelm). Dep. of Horticulture, Univ. of Nebraska, Lincoln.
- Riordan T.P., de Shazer S.A., Johnson-Cicalese J.M., Baxendale F.P., Engleke M.C., Gaussoin R.E., Horst G.L., Shearman R.C. Registration of `315' buffalograss. Crop Sci. 1995;35:1206.[Free Full Text]
- Riordan T.P., deShazer S.A., Johnson-Cicalese J.M., Shearman R.C. An overview of breeding and development of buffalograss. Int. Turfgrass Soc. Res. J. 1993;7:816-822.
- Riordan T.P., Gaussoin R.E., Shearman R.C., Johnson P.G., Johnson-Cicalese J., Baxendale F.B., Klucas R.V. Registration of `118' buffalograss. Crop Sci. 2000;40:570-571.
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ABSTRACT
INTRODUCTION
