Golf greens and fairways planted to creeping bentgrass (Agrostis stolonifera), colonial bentgrass (A. capillaris), and velvet bentgrass (A. canina) require overseeding to reestablishment areas damaged from winter injuries. Cold soil temperatures (≈10 °C) typical of early spring plantings in the northern United States reduce seed germination and establishment vigor of cool-season grasses when compared with more favorable soil temperatures of 20 to 30 °C (He et al., 2013; Liu et al., 2001; McGinnies, 1960; Wright et al., 1978). Delayed growth shortens the growing period of seedling grasses and results in lower plant numbers in turf stands (Larsen et al., 2004), which are more susceptible to competition for moisture and summer drought (Young and Evans, 1982) and to competition from weeds during the establishment phase (Murphy et al., 2005).
Seed germination is the initial step in establishment, and rapid establishment can mitigate costs and revenue loss when golf courses openings are delayed. High-quality seed and seedling vigor is characterized by high viability (more germinating seeds). Emergence is the point that the primary leaf emerges from the soil surface followed by growth and development of roots, stolons, and rhizomes to form a dense turf. Seedling emergence, seedling vigor, and mature plant growth are distinct but related stages. Numerous studies have investigated laboratory seed germination characteristics such as final germination percentage and mean germination times that are conducted under controlled temperatures and moisture. It has been suggested the rate of growth after emergence is determined largely by the genotype and environment and not by the rate of seed germination (Argerich et al., 1990; Scott and Jones, 1985; Yamamoto et al., 1997a). For example, Yamamoto et al. (1997b) found the rate of emergence of the second and third leaves in kentucky bluegrass (Poa pratensis) to be under genetic control.
Unlike controlled environments, seeds are exposed to variable and unfavorable temperature and soil moisture in the field that delay and postpone germination, thereby affecting establishment (Happ et al., 1993). Germination of rough bluegrass (Poa trivialis) in the growth chamber at 10 °C provided two to three times the germination rate observed in the field when rough bluegrass was over-seeded into hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) putting greens (Liu et al., 2001). Emergence of perennial ryegrass (Lolium perenne) seeded on compacted soil cores was only 40% to 69% of that observed under optimal germination when assayed on moist paper (Snapp et al., 2008). Total emergence and emergence rates in the field have been shown to be lower than emergence responses in the laboratory for cool-season range grasses (Hardegree and Van Vactor, 2000). These same authors reported greater germination in laboratory tests than measured in the field during early spring planting dates. Laycock and Shildrick (1979), however, found some positive correlation between perennial ryegrass laboratory germination and initial establishment measured in the field during the time between the sowing date (seed germination and emergence phase) and before the first mowing (maturity).
Soil temperature, water potential, and oxygen levels are important environmental factors affecting seed germination and influencing the seedlings to emerge from the soil (Burris, 1976; Pollock, 1972; Powell, 1988). Beard (1979) found the base temperatures (Tb), below which no germination is observed, to be ≈7 °C for perennial ryegrass and 11 °C for creeping bentgrass. Trudgill et al. (2000) reported colonial bentgrass Tb of 8 °C, and perennial ryegrass exhibited a Tb of 5 °C. The final stage of establishment involves mature roots, shoots, and lateral stems to form, which is a distinctly different phase from seed germination and emergence (Beard, 1973). As such, constant temperature and moisture regimes typical of germination laboratory tests are not necessarily predictive of field performance (Steiner et al., 1989; Trawatha et al., 1990).
Seed requires an accumulation of time and temperature (“thermal-time”) above Tb to germinate (Larsen and Bibby, 2005; Larsen et al., 2004) and in turn, to establish. Nonlinear regression thermal-time models have been used for seed germination and emergence (Larsen and Bibby, 2005; Larsen et al., 2004; Zhang et al., 2013). Monitoring soil temperatures after seedling emergence in the field until a mature stand is formed (i.e., requiring frequent mowing) has not been investigated in bentgrass species (Agrostis sp.) and cultivars. Growing degree day (GDD) models have been computed using soil or air temperatures collected daily. Base temperature varies with the crop with GDD for warm-season turfgrass establishment calculated using Tb close to 5 °C (Frank et al., 1998; Patton et al., 2004; Shahba and Qian, 2008; Unruh et al., 1996), while for cool-season lawn grass species, values of Tb for seed germination ranged from 1.6 to 3.6 °C (Larsen and Bibby, 2005), with bentgrass species exhibiting Tb closer to 10 °C (Heineck et al., 2018; Trudgill et al., 2000).
Identifying bentgrass species and cultivars with the potential to establish under low soil temperatures would be beneficial toward achieving more mature stands earlier in the spring. Simulated field-temperature studies have been conducted in cool-season range grasses (Hardegree and Van Vactor, 1999), cool-season lawn grasses (Larsen and Bibby, 2005), and in cool-season turfgrass for golf use such as bentgrass species and cultivars (Heineck et al., 2018). However, these responses were not validated in the field. Subsequently, Hardegree and Van Vactor (2000) reevaluated their previous findings and found simulated soil temperature models predicted greater germination than measured in the field, and they reported total emergence in the field to be more variable. While bentgrass species and cultivars have been tested in laboratory settings, there is a need to study cold temperature germination of these grasses in the field. Our research objective was to identify bentgrass species and cultivars with the capacity to establish to maturity in the shortest time and under cooler soil temperatures during an early spring planting date.
Argerich, C.A., Bradford, K.J. & Ashton, F.M. 1990 Influence of seed vigor and preplant herbicides on emergence, growth, and yield of tomato HortScience 25 288 291 doi: 10.21273/HORTSCI.25.3.288
Beard, J.B. 1973 Turfgrass science and culture. Prentice Hall, Englewood Cliffs, NJ
Beard, J.B. 1979 Minimum temperature requirements for seed germination of turfgrasses. Proc. Texas Turfgrass Conf. College Station, 3–5 Dec. 1979. p. 82–86
Brown, K.R. 1977 Parent seed weight, plant growth, and seeding in ‘Grassland Tama’ westerwolds ryegrass N. Z. J. Exp. Agr. 5 143 146 doi: 10.1080/03015521.1977.10425953
Christians, N.E., Wilkinson, J.F. & Martin, D.P. 1979 Variations in the number of seeds per unit weight among turfgrass cultivars Agron. J. 71 415 419 doi: 10.2134/agronj1979.00021962007100030008x
Egli, D.B. & TeKrony, D.M. 1996 Seedbed conditions and prediction of field emergence of soybean seed J. Prod. Agr. 9 365 370 doi: 10.2134/jpa1996.0365
Frank, K.W., Gaussoin, R.E., Riordan, T.P. & Miltner, E.D. 1998 Date of planting effects on seeded turf-type buffalograss Crop Sci. 38 1210 1213 doi: 10.2135/cropsci1998.0011183X003800050016x
Happ, K., McDonald, M.B. & Danneberger, T.K. 1993 Vigor testing in perennial ryegrass (Lolium perenne L.) seeds Seed Sci. Technol. 21 375 381
Hardegree, S.P. & Van Vactor, S. 1999 Predicting germination response of four cool-season range grasses to field-variable temperature regimes Environ. Exp. Bot. 41 209 217 doi: 10.1016/S0098-8472(99)00004-0
Hardegree, S.P. & Van Vactor, S. 2000 Germination and emergence of primed seeds under field and simulated-field temperature regimes Ann. Bot. 85 379 390 doi: 10.1006/anbo.1999.1076
He, J.Y., Wang, J.T., Bai, X.M., Dong, Q. & Lu, Y.W. 2013 Effects of temperature on seed germination characteristics of eight wild Poa germplasm Pratacult. Sci. 30 383 389
Hegarty, T.W. 1973 Temperature relations of germination in the field, p. 411–432. In: W. Heydecker (ed.). Seed ecology. Butterworths, London, UK
Heineck, G.C., Bauer, S.J., Cavanaugh, M., Hollman, A., Watkins, E. & Horgan, B.P. 2018 Variability in creeping bentgrass cultivar germinability as influenced by cold temperatures Crop Forage Turfgrass Mgt. 5 1 7 doi: 10.2134/cftm2018.07.0054
Jiang, Y. 2008 Identification of turfgrass stress utilizing spectral reflectance, p. 547–556. In: M. Pessarakli (ed.). Handbook of turfgrass management and physiology. CRC Press, Boca Raton, FL. doi: 10.1201/9781420006483.ch32
Johnsen, A.R., Horgan, B.P., Hulke, B.S. & Cline, V. 2009 Evaluation of remote sensing to measure plant stress in creeping bentgrass (Agrostis stolonifera L.) fairways Crop Sci. 49 2261 2274 doi: 10.2135/cropsci2008.09.0544
Larsen, S.U. & Andreasen, C. 2004 Light and heavy turfgrass seeds differ in germination percentage and mean germination thermal time Crop Sci. 44 1710 1720 doi: 10.2135/cropsci2004.1710
Larsen, S.U. & Bibby, B.M. 2004 Use of germination curves to describe variation in germination characteristics in three turfgrass species Crop Sci. 44 891 899 doi: 10.2135/cropsci2004.8910
Larsen, S.U. & Bibby, B.M. 2005 Differences in thermal time requirement for germination of three turfgrass species Crop Sci. 45 2030 2037 doi: 10.2135/cropsci2004.0731
Larsen, S.U., Andreasen, C. & Kristoffersen, P. 2004 Differential sowing time of turfgrass species affects the establishment of mixtures Crop Sci. 44 1315 1322 doi: 10.2135/cropsci2004.1315
Laycock, R.W. & Shildrick, J.P. 1979 Multi-centre trials of turfgrass cultivars in the U.K. No. 1. Lolium perenne (perennial ryegrass), (1974-8) J. Sports Turf Res. Inst. 55 7 35
Lee, H., Bremer, D.J., Su, K. & Keeley, S.J. 2011 Relationships between normalized difference vegetation index and visual quality in turfgrasses: Effects of mowing height Crop Sci. 51 323 332 doi: 10.2135/cropsci2010.05.0296
Liu, C., Camberato, J.J., Martin, S.B. & Turner, A.V. 2001 Rough bluegrass germination varies with temperature and cultivar/seed lot HortScience 36 153 156 doi: 10.21273/HORTSCI.36.1.153
McGinnies, W.J. 1960 Effects of moisture stress and temperature on germination of six range grasses Agron. J. 52 159 162 doi: 10.2134/agronj1960.00021962005200030012x
Moot, D.L., Scott, W.R., Roy, A.M. & Nicholls, A.C. 2000 Base temperature and thermal time requirements for germination and emergence of temperate pasture species N. Z. J. Agr. Res. 43 15 25 doi: 10.1080/00288233.2000.9513404
Murphy, J.A., Samaranayake, H., Lawson, T.J., Honig, J.A. & Hart, S. 2005 Seeding date and cultivars impact on establishment of bentgrass in soil containing annual bluegrass seed Intl. Turfgrass Soc. Res. J. 10 410 415
Patton, A.J., Hardebeck, G.A., Williams, D.W. & Reicher, Z.J. 2004 Establishment of bermudagrass and zoysiagrass by seed Crop Sci. 44 2160 2167 doi: 10.2135/cropsci2004.2160
Pollock, B.M. 1972 Effects of environment after sowing on viability, p. 150–171. In: E.H. Roberts (ed.). Viability of seeds. Syracuse Univ. Press, Syracuse, NY. doi: 10.1007/978-94-009-5685-8_6
Scott, S.J. & Jones, R.A. 1985 Cold tolerance in tomato. I. Seed germination and early seedling growth of Lycopersicon esculentum Physiol. Plant. 65 487 492 doi: 10.1111/j.1399-3054.1985.tb08678.x
Shahba, M.A. & Qian, Y.L. 2008 Effect of seeding date, seeding rate, and seed treatments on saltgrass seed germination and establishment Crop Sci. 48 2453 2458 doi: 10.2135/cropsci2008.02.0076
Snapp, S., Price, R. & Morton, M. 2008 Seed priming of winter annual cover crops improves germination and emergence Agron. J. 100 1506 1510 doi: 10.2134/agronj2008.0045N
Steiner, J.J., Grabe, D.F. & Tulo, M. 1989 Single and multiple vigor tests for predicting seedling emergence of wheat Crop Sci. 29 782 786 doi: 10.2135/cropsci1989.0011183X002900030049x
Trawatha, S.E., Steiner, J.J. & Bradford, K.J. 1990 Laboratory vigor tests used to predict pepper seedling field emergence performance Crop Sci. 30 713 717 doi: 10.2135/cropsci1990.0011183X003000030048x
Trudgill, D.L., Squire, G.R. & Thompson, K. 2000 A thermal time basis for comparing the germination requirements of some British herbaceous plants New Phytol. 145 107 114 doi: 10.1046/j.14698137.2000.00554.x
Unruh, J.B., Gaussoin, R.E. & Weist, S.C. 1996 Basal growth temperatures and growth rate constants of warm-season turfgrass species Crop Sci. 36 997 999 doi: 10.2135/cropsci1996.0011183X0036000400030x
Veronesi, F., Damiani, F., Grando, S. & Falcinelli, M. 1983 The influence of seed weight on establishment and productivity in the first year in Lolium perenne L Genet. Agrar. 37 391 402
Weaich, K., Bristow, K.L. & Cass, K.L. 1996 Simulating maize emergence using soil and climatic data Agron. J. 88 667 674 doi: 10.2134/agronj1996.00021962008800040028x
Wright, D.L., Blazer, R.E. & Woodruff, J.M. 1978 Seedling emergence as related to temperature and moisture tension Agron. J. 70 709 712 doi: 10.2134/agronj1978.00021962007000050001x
Yamamoto, I., Turgeon, A.J. & Duich, J.M. 1997a Field emergence of solid matrix primed turfgrasses Crop Sci. 37 220 225 doi: 10.2135/cropsci1997.0011183X003700010038x
Yamamoto, I., Turgeon, A.J. & Duich, J.M. 1997b Seedling emergence and growth of solid matrix primed kentucky bluegrass seed Crop Sci. 37 225 229 doi: 10.2135/cropsci1997.0011183X003700010039x
Young, J.A. & Evans, R.A. 1982 Temperature profiles of cool season grasses. U.S. Dept. Agr., Agr. Res. Serv., Western Reg. ARR-W-27
Zhang, H., McGill, C.R., Irving, L.J., Kemp, P.D. & Zhou, D. 2013 A modified thermal time model to predict germination rate of ryegrass and tall fescue at constant temperatures Crop Sci. 53 240 249 doi: 10.2135/cropsci2012.02.0085