PDF version
for printing

Impact
Statement

© 2007 Plant Management Network.
Accepted for publication 15 August 2007. Published 12 September 2007.

Moderate Salinity Does Not Affect Germination of Several Cool- and Warm-Season Turfgrasses

Casey J. Johnson and Bernd Leinauer, Department of Extension Plant Sciences, and April L. Ulery, Department of Plant and Environmental Sciences, New Mexico State University, Las Cruces 88003; Douglas E. Karcher, Department of Horticulture, University of Arkansas, Fayetteville 72701; and Ryan M. Goss, Department of Plant and Environmental Sciences, New Mexico State University, Las Cruces 88003

Corresponding author: Bernd Leinauer. leinauer@nmsu.edu

Johnson, C. J., Leinauer, B., Ulery, A. L., Karcher, D. E., and Goss, R. M. 2007. Moderate salinity does not affect germination of several cool- and warm-season turfgrasses. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-0912-01-RS.

Abstract

Germination of warm- and cool-season turfgrasses was assessed at salinity levels commonly found in recycled irrigation water. Cool-season grass seeds included in the study were Thermal Blue hybrid bluegrass [Poa arachnifera (Torr.) × pratensis (L.)]; Barlexas II, Southeast, and Tar Heel II tall fescue [Festuca arundinacea (Schreb.)]; Brightstar SLT and Catalina perennial ryegrass [Lolium perenne (L.)]; Salty and Fults alkaligrass [Puccinellia distans (Jacq.)]; and Dawson red fescue [Festuca rubra trichophylla (L.)]. Warm-season grass seeds used in the study were bermudagrass Numex Sahara, Princess 77, and Transcontinental [Cynodon dactylon (L.)]; Companion zoysiagrass [Zoysia japonica (Steud)]; and Seaspray seashore paspalum [Paspalum vaginatum (Swartz)]. Each grass was incubated at salinity levels from 0.6 to 3.0 dS/m. Germination was considered successful upon radicle emergence and the first leaf growing past the coleoptile. Despite species and cultivar variation in germination success, germination was not inhibited in any of the tested cultivars at the salinity levels used in this study, suggesting that germination may not be the most salt-sensitive stage in turfgrass development.

Introduction

Turfgrass is a major crop worldwide and one of the most important components of the tourism industry in the southwestern United States. In New Mexico alone, the turfgrass and golf sector contributed a total of $975,000,000 in revenues to the state’s economy during the fiscal year of 2004-2005 (5). However, population growth and diminishing available water supplies in the Southwest and other arid regions of the world call for innovative ways to reduce potable water consumption for irrigation. These include using recycled, reclaimed, effluent, or reused water, all terms referring to water which has been treated for reuse purposes after undergoing at least one cycle of human use (8). A large supply of groundwater in New Mexico is saline (28) and non-potable, like recycled water (12), and could also potentially be used for turfgrass irrigation. In arid environments with limited potable water, such as New Mexico, turfgrass research focusing on salinity tolerance is critical to ensuring the continued economic contribution of the turfgrass industry to the state.

Past studies have investigated the effects of salinity on physiological and biochemical processes in plants (17,21), salt disruption of metabolic processes and decreased water potential in the soil leading to decreased water uptake by roots (10), and on salinity levels in both plant tissue and soil (4,16,18). In these studies, researchers used salinity levels ranging from 0.7 to 30 dS/m. The high end of this range is probably of little or no value to turf managers, as these salinity levels are much greater than those occurring in reclaimed waters, which are increasingly used for turfgrass irrigation (3).

Germination sensitivity to salt stress has been used as a predictor of a plant’s ability to reach maturity (6) and numerous studies have examined sensitivity of turfgrass seeds to salinity. However, results of these studies vary among species and in some cases give conflicting information about the same species. Some grass species appear to tolerate high salinity levels without any deleterious effects. Zhang et al. (30) found no significant effects on the germination of tall wheatgrass [Thinopyrum ponticum (Podp.)] at NaCl concentrations as high as 153.8 mmol (13.8 dS/m). Horst and Dunning (11) tested 48 perennial ryegrasses [Lolium perenne (L.)] and found that salt levels as high as 23.4 dS/m had no significant effect on germination.

In contrast, other studies have reported reduced germination under similar salinity levels. For example, Wu and Lin (29) observed a significant reduction in buffalograss [Buchloe dactyloides (Nutt)] germination at NaCl concentrations of 50 mmol (4.5 dS/m). Camberato and Martin (2) reported a 3% reduction in germination of rough bluegrass [Poa trivialis (L.)] when salinity was increased to 5 dS/m. Harivandi et al. (9) reported that germination in ‘Pennfine’ perennial ryegrass, ‘Seaside’ creeping bentgrass [Agrostis palustris (Huds.)], ‘Dawson’ creeping red fescue [Festuca rubra trichophylla (L.)], and ‘Fults’ weeping alkaligrass [Puccinellia distans (Jacq.)] was reduced by 20, 22, 26, and 48%, respectively, in soils with an EC of 3.3 dS/m when compared to seed placed in straight sand and watered with tap water. Even within the same species, tolerance to saline conditions can vary. For example, Hanslin and Eggen (7) reported no effects on germination of creeping bentgrass cvs. Providence and Kromi and colonial bentgrass [Agrostis capillaris (L.)] cv. Vivaldi at salinity levels as high as 22 dS/m. In contrast, McCarty and Dudeck (19) reported that salinity levels between 11,800 mg/liter (≈18.4 dS/m) and 14,700 mg/liter (≈23 dS/m) reduced germination of colonial bentgrasses cvs. Colonial and Highland and creeping bentgrasses cvs. Pennlinks, Penncross, and Penneagle by 50%.

Some of the differences observed in past salinity tolerance studies may be explained by their use of different end points to express successful germination of grass plants. Some studies focused on determining thresholds that inhibited radicle emergence during germination (14,24). Others required a radicle to emerge and a leaf to have visibly grown through the coleoptile before germination was considered successful (2,7,15). Using the presence of radicles as the sole measure of successful germination has its limitations. Radicle emergence during germination can be accompanied by a primary leaf that is lodged in the coleoptile, a leaf that is shredded and unable to completely develop, or no leaf at all, all scenarios resulting in the death of the plant. Photosynthetic tissue must be present in combination with root growth for seedlings to successfully transition to high quality turf. During early germination stages, the plant is able to survive heterotrophically on carbohydrates from the endosperm; young seedlings not developed to the point of self-sufficiency upon consumption of the endosperm cannot survive. Therefore, turfgrass selection decisions regarding saline irrigation should not be made using radicle emergence data alone, unless accompanied by seedling and establishment data.

The objective of this study was to assess germination success of several warm- and cool-season grasses irrigated with water at salinity levels that were representative of those commonly found in reclaimed irrigation water. To do so, we compared germination success at salinity levels of 0.6, 2.0, and 3.0 dS/m. Germination was defined in our study as the point when both radicle emerged and a leaf had visibly grown through the coleoptile.

Project Design

Four separate germination incubator experiments with seeds from warm- and cool-season grasses were conducted at the New Mexico Department of Agriculture Seed Testing Lab between January 2005 and May 2006. Experiments included either nine cool-season or four warm-season grass cultivars and was repeated once for each group of grasses. Seashore paspalum [Paspalum vaginatum (Swartz)] cv. Seaspray was included only in the second experiment of the warm season. For all other grasses new seed from separate seed lots were used for the second run of each experiment. Cool-season grass seeds included in the study were hybrid bluegrass [Poa arachnifera (Torr.) × pratensis (L.)] cv. Thermal Blue; tall fescue [Festuca arundinacea (Schreb.)] cvs. Barlexas II, Southeast, and Tar Heel II; perennial ryegrass [Lolium perenne (L.)] cvs. Brightstar SLT and Catalina; alkaligrass cvs. Salty and Fults; and red fescue cv. Dawson. Warm-season grass seeds used in the study were bermudagrass [Cynodon dactylon (L.)] cvs. Numex Sahara, Princess 77, and Transcontinental; zoysiagrass [Zoysia japonica (Steud)] cv. Companion; and seashore paspalum [Paspalum vaginatum (Swartz)] cv. Seaspray. Fifty seeds of each cultivar were placed onto blotter paper in a germination tray measuring 11.75 cm in width, 11.75 cm in length, and 2.85 cm in height. The germination tray was subsequently placed into a germination incubator and water of the assigned salinity treatment level was added to provide adequate moisture. Saline water of the assigned salinity treatment level was also used to re-moisten the trays when necessary and to maintain adequate moisture levels throughout the experimental period, which ended 28 days after seeding (DAS). Climate conditions for the cool-season grasses were kept at 15°C for 16 h in the dark and at 25°C for 8 h under light. Warm-season conditions were set at 20°C for 16 h (dark) and 35°C for 8 h (light). Study parameters were set based on seed testing guidelines (13). Salt solutions were prepared using dilutions of saline ground water. Exact chemical composition of the treatment waters are listed in Table 1. Unlike many past studies in which extremely high levels of salinity were often used to test tolerances in turf, the salinity levels we tested were comparatively low and ranked non-saline (0.6 dS/m), slightly saline (2.0 dS/m), and moderately saline (3.0 dS/m) (25). Standards set by the US Salinity Laboratory (27) rated our salinity levels medium (0.6 dS/m), high (2.0 dS/m), and very high (3.0 dS/m). Our aim was to use environmentally realistic salinity values that were typical of those found in reclaimed water commonly used for turfgrass irrigation (12). The lowest salinity treatment (0.6 dS/m) was used as the control. No fertilizer was applied to seeds, eliminating any additional source of salt to the treatments. Germination trays were checked every other day to maintain adequate moisture. Blotter papers in the trays were kept moist to maintain a humid atmosphere without visible pooling of water to prevent poor germinating conditions. Germinated seeds were counted twice weekly beginning at 7 days after seeding. Seeds were only considered germinated with the presence of a leaf extended past the coleoptile and a visible radicle. After a seed was considered germinated, it was counted and the seedling was removed. Final germination was determined on a percentage basis at the completion based on the number of germinated seeds up to and including 28 days after seeding.

Table 1. Chemical analysis of non-saline, slightly saline, and moderately saline water used in the study.

The experimental design was a two-factor randomized complete block with cultivar and salinity level as the treatment factors. Each cultivar × salinity level combination was replicated three times within the incubator and blocked by incubator shelves. Each of the four germination experiments was analyzed separately. Data were subjected to analysis of variance using SAS Proc Mixed (SAS Institue Inc., Cary, NC) followed by multiple comparisons of means using Fisher's LSD test at the 0.05 probability level.

Salinity Effect on Germination

Our results indicated that salinity levels of 3.0 dS/m and lower had no negative affect on germination of any cultivars tested (Table 2). These results are contrary to findings of Harivandi et al. (9), who reported a significant reduction in germination of weeping alkaligrass cv. Fults, perennial ryegrass cv. Pennfine, and creeping red fescue cv. Dawson at a soil salinity level of 3.3 dS/m when compared to seed placed in straight sand and watered with tap water. However, comparisons between the two studies are difficult to make as very different methodologies were used. Our findings do, however, concur with those of Peacock and Dudeck (23), who also reported no reduction in germination of bermudagrass under salinity levels similar to those used in this study. We found no published studies on seedling salinity tolerance of recently introduced grasses such as hybrid bluegrass or Seashore paspalum. Our results indicate that germination of both of these species was unaffected by irrigation salinity levels of up to 3 dS/m.

Table 2. Analysis of variance, testing the main effects and interactions of turfgrasses (variety) and water quality (Salinity) on seedling germination in 2 experiments of warm- and cool-season turfgrasses (28 days after seeding).

  *  Significant F test at the 0.05 level of probability.

 ** Significant F test at the 0.001 level of probability.

  ‡  NS = Not significant at the 0.05 probability level.

Germination Difference Among Species

Differences in germination success were observed among both cool-season and warm-season grasses. For the cool-season grasses, overall germination success ranged from 74% for tall fescue Southeast to 95% for perennial ryegrass Brightstar SLT at 28 DAS (Table 3). Red fescue Dawson showed significantly lower germination in both experiments compared to all other cool-season grasses, with the exception of tall fescue Southeast in experiment 1 (Table 3). Palazzo and Brar (22) found similar lower germination success for Dawson when compared to other fescue grasses.

Table 3. Percent germination of several cool-season turfgrass species up to and including 28 days after seeding. Data are pooled over water source. Germination was conducted in moisture chambers at day/night cycles of 8/16 h at 15/25°C.

 * Values within columns followed by the same letter are not significantly different (Fischer’s protected LSD, α = 0.05).

We also observed differences in germination (for three species) between experiments. Southeast, Fults, and Thermal Blue had lower germination in the first experiment than in the second (Table 3). Different germination rates in the two experiments could be attributed to differences in seed lots. Camberato and Martin (3) also reported differences in germination between experiments and attributed them to different seed lots.

For the warm-season grasses, Princess 77, Sahara, and Transcontinental bermudagrasses had the highest germination success (Table 4). In experiment 1, Transcontinental germinated significantly more than Princess 77, and in experiment 2 it germinated significantly more than Princess 77 and Sahara. Germination differences between different varieties of bermudagrass have been reported in field trials (26). However, in the aforementioned study the differences in germination success changed between years. In the first year Princess 77 had significantly more germination than Riviera, while in the second year of the study the opposite was observed (26). We also observed differences in germination from one experiment to another (Table 4). These differences are probably also due to differences in seed lots, as noted by Camberato and Martin (2). Despite some differences in germination observed between experiments, overall tolerance to salinity did not change.

Table 4. Percent germination of warm-season turfgrass species 28 days after seeding. Data are pooled over 3 salinity levels. Germination was conducted in moisture chambers at day/night cycles of 8/16 h at 20/35°C.

 * Values within columns followed by the same letter are not significantly different from one another (Fischer’s protected LSD, α = 0.05).

Comparisons between the results we observed under controlled laboratory settings and those obtained from similar field studies are difficult because of the paucity of published studies that investigated the effects of moderate irrigation water salinity on seed germination in the field. In a cucumber greenhouse experiment using irrigation water of comparable salinities (1.54 and 3.1 dS/m) to those we used in our study, Blanco and Folegatti (1) found that soil salinity levels increased over 57 days after saline irrigation was initiated and corresponded to salinity levels in the irrigation water used. In an artichoke study conducted by Mauromicale and Licandro (20) soil salinity only increased from 0.5 to 2.3 dS/m in the top 5 cm of a loamy sand despite being irrigated for 15 days with highly saline irrigation water of -0.5 MPa (approximately 13.5 dS/m). These studies suggest that salt accumulation in soils over short term periods such as those we used in our germination study will not exceed levels found in recycled waters commonly used to irrigate turfgrass. Unlike the aforementioned studies where salinity levels were measured in the soils at the end of the trial period, we did not measure salinity on the blotter papers used to germinate the seeds because no studies have reported salinity levels on blotter paper or described methods to do so. However, given the fact that we used saline water of the corresponding salinity treatment to re-moisten the germination trays when necessary, we assumed that salt would accumulate on the blotter paper as it would in soils and that the final salinity of the blotter paper would be at least as high as the treatment water added.

Conclusions

Despite differences in germination success observed among species and between seed lots used, saline water of 3 dS/m and lower did not affect germination in any of the species and cultivars tested. Based on our results, salt levels found in reclaimed water and currently used for irrigation should not affect germination. However, the range of germination found in this study and the range of salinity affecting germination of turfgrasses in general reported in the literature highlights the importance of testing each species and cultivar of interest.

Acknowledgments

Financial support to conduct the study was provided by the Cooperative State Research, Education, and Extension Service, US Department of Agriculture under Agreement No. 2005-34461-15661 and 2005-45049-03209, New Mexico State Water Resources Resource Institute, and New Mexico State University’s Agricultural Experiment Station. We are grateful to Richard Kochevar and the New Mexico Department of Agriculture Seed Testing Laboratory for providing facilities and assistance with the study. The manuscript benefited greatly from comments and suggestions made by Rossana Sallenave.

Literature Cited

1. Blanco, F. F., and Folegatti, M. V. 2002. Salt accumulation and distribution in a greenhouse soil as affected by salinity of irrigation water and leaching management. Revista Brasiliera de Engenharia Agricola e Ambiental. 6:414-419.

2. Camberato, J. J., and Martin, S. B. 2004. Salinity slows germination of rough bluegrass. HortScience. 39:394-397.

3. Carrow, R. N., and Duncan, R. R. 1998. Salt-affected turfgrass sites. Ann Arbor Press, Chelsea, MI.

4. Dean-Knox, D. E., Devitt, D. A., Verchick, L. S., and Morris, R. L. 1998. Physiological response of two turfgrass species to varying ratios of soil matric and osmotic potentials. Crop Sci. 38:175-181.

5. Diemer, J. 2006. Economic Impact: Golf and Turfgrass in New Mexico 2004-2005. Dept. of Agric. Econ. & Agric. Business, New Mexico State Univ., Las Cruces, NM.

6. Dewey, D. R. 1962. Germination of crested wheatgrass in salinized soil. Agron. J. 54:353-355.

7. Hanslin, H. M., and Eggen, T. 2005. Salinity tolerance during germination of seashore halophytes and salt-tolerant grass cultivars. Seed Sci. Res. 15:43-50.

8. Harivandi, M. A. 2004. A review of sports turf irrigation with municipal recycled water. Acta Hortic. 661:131-136.

9. Harivandi, M. A., Butler, J. D., and Soltanpour, P. M. 1982. Salt influence on germination and seedling survival of six cool season turfgrass species. Commun. Soil Sci. Plant Anal. 13:519-529.

10. Hasegawa, P. M., Bressan, R. A., Zhu, J. K., and Bohnert H. J. 2000. Plant cellular and molecular responses to high salinity. Ann. Rev. of Plnt. Phys. and Plnt. Mol. Bio. 51:463-499.

11. Horst, G. L., and Dunning, N. B. 1989. Germination and seedling growth of perennial ryegrasses in soluble salts. J. Amer. Soc. Hort. Sci. 114:338-342.

12. Huck, M., Carrow, R. N., and Duncan, R. R. 2000. Effluent water: Nightmare or dream come true? USGA Green Sec. Rec. 38:15-29.

13. ISTA. 1999. International Rules for Seed Testing. Seed Sci. Tech 27:1-333.

14. Larsen, S. U., and Bibby, B. M. 2004. Use of germination curves to describe variation in germination characteristics in three turfgrass species. Crop Sci. 44:891-899.

15. Marcar, N. E. 1987. Salt tolerance in the genus lolium (ryegrass) during germination and growth. Austr. J. Agric.Res. 38:297-307.

16. Marcum, K. B. 1999. Salinity tolerance mechanisms of grasses in the subfamily chloridoidae. Crop Sci. 39:1153-1160.

17. Marcum, K. B., Anderson, S. J., and Engelke, M. C. 1998. Salt gland ion secretion: A salinity tolerance mechanism among five zoysiagrass species. Crop Sci. 38:806-810.

18. Marcum, K. B., and Murdoch, C. L. 1990. Growth responses, ion relations, and osmotic adaptations of eleven C₄ turfgrasses to salinity. Agron. J. 82:892-896.

19. McCarty, I. B., and Dudeck A. E. 1993. Salinity effects on bentgrass germination. HortScience 28:15-17.

20. Mauromicale, G., and Licandro, P. 2002. Salinity and temperature effects on germination, emergence, and seedling growth of globe artichoke. Agronomie 22:443-450.

21. Nabati, D. A., Schmidt, R. E., and Parrish, D. J. 1994. Alleviation of salinity stress in Kentucky bluegrass by plant growth regulators and iron. Crop Sci. 34:198-202.

22. Palazzo, A. J., and Brar, G. S. 1997. The effects of temperature on germination of eleven Festuca cultivars. US Army Corp of Eng. Spec. Rep. 97-19.

23. Peacock, C. H., and Dudeck, A. E. 1989. Influence of salinity on warm season turfgrass germination. Int. Turfgrass Soc. Res. J. 6:229-231.

24. Qian, Y. L., and Suplick, M. R. 2001. Interactive effects of salinity and temperature on Kentucky bluegrass and tall fescue seed germination. Intl. Turfgrass Soc. 9:334-339

25. Rhoades, J. D., Kandidah, A., Mashali, A. M. 1992. The use of saline waters for crop production. Irrigation and Drainage Paper No. 48. Food and Agric. Organ. of the United Nations (FAO) Italy, Rome.

27. Shaver, B. R., Richardson, M. D., McCalla, J. H., Karcher, D. E., and Berger, P. J. 2006. Dormant seeding bermudagrass cultivars in a transition zone environment. Crop Sci. 46:1787-1792.

28. US Salinity Laboratory. 1954. Diagnosis and improvement of saline and alkaline soils. Agric. Handbook 60., USDA, Washington, DC.

29. Witcher, J. C., and Cunniff, R. A. 2002. Geothermal energy at New Mexico State University in Las Cruces. GHC Bull. 12:30-36.

30. Wu, L., and Lin, H. 1993. Salt concentration effects on buffalograss germplasm seed germination and seedling establishment. Int. Turfgrass Soc. Res. J. 7:823-828.

31. Zhang, B., Jacobs, B. C., O’Donnell, M., and Guo, J. 2005. Comparative studies on salt tolerance of seedlings for one cultivar of puccinellia (Puccinellia ciliata) and two cultivars of tall wheatgrass (Thinopyrum ponticum). Austr. J. Exp. Agric. 45:391-399.