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| Web URL(s): | http://archive.lib.msu.edu/tic/rpr/1986/9246, Texas A&M, Beard.PDF
Last checked: 03/28/2013
Requires: PDF Reader |
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| Publication Type:
| Report |
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| Material Type: | Manuscript |
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| Monographic Author(s): | Beard, James B. |
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| Author Affiliation: | Turfgrass Physiologist, Texas A&M University |
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| Monograph Title: | Third Year Progress Report Concerning Physiological Investigations in Developing Water Conserving, Minimal Maintenance Turfgrasses and Cultural Systems: Volume III, 1986. |
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| Publishing Information: | [College Station, Texas]: Texas A&M University |
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| # of Pages: | 21 |
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| Collation: | i, 20 pp. |
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| Abstract/Contents: | "The research accomplishments of the first two years were summarized in the Executive Summary contained in the Progress Report, Volume II, October, 1985. The following listing contains those research conclusion drawn during the third year of USGA funding. 1. Visual assessment via the high canopy resistance - low leaf area concept offers a rapid, economical approach for screening large numbers of mowed bermudagrass or mowed zoysiagrass clonal plantings under field conditions for low water use rates. 2. Observer training and enhanced experience with this technique will ensure the best possible accuracy. 3. Visual assessment via the high canopy resistance - low leaf area concept offers a rapid, economical approach for screening large numbers of unmowed bermudagrass clonal plantings for low evapotranspiration rates under field conditions. 4. A procedure for incorporating radioactive 14CO2 into turfs and then assaying shoot and root sections for radioactivity has been successfully developed and tested for use in rooting studies. 5. A system for growing turf, enabling the harvest of the entire root system with undamaged root hairs has been successfully developed and tested. 6. Substantial differences in terms of root hair distribution and length are evident among 13 warm-season turfgrass species. 7. The eleven major warm-season turfgrass species and cultivars vary substantially in drought resistance. 8. The mechanism of drought resistance varies among the warm-season turfgrass species. 9. Of the species studied, zoysiagrass, centipedegrass, and bermudagrass are more drought resistant than St. Augustinegrass and seashore paspalum. 10. A high leaf water potential, extensive root system, and high wax cover over the stomata contribute a high level of drought avoidance in bermudagrass and centipedegrass. This was confirmed by the higher leaf firing in the polyethylene glycol solution. 11. Since zoysiagrass possessed a shallow root system and low leaf water potential, a high drought tolerance is probably the major mechanism contributing to drought resistance. Low leaf firing in the polyethylene glycol solution supports this conclusion. 12. Early stomatal closure, degree of wax accmulation [accumulation], rooting potential, and leaf firing contribute significantly to the avoidance dimension of drought resistance in warm-season turfgrasses. 13. Zoysiagrasses possess especially strong drought resistance due primarily to internal drought tolerance mechanisms. 14. Root extension length did not appear to be the controlling factor in drought resistance or the avoidance dimension. Tifway bermudagrass and St. Augustinegrass had long extensions, but poor drought resistance. Conversely, Texturf 10 and Tifgreen bermudagrasses had long extension and good resistance. Total root dry weight and root shoot ratio were similarly split, and no firm conclusion can be made. 15. With the exception of the St. Augustinegrass, it appears that the total number of roots in the soil profile is what influences which species are the most drought resistance. 16. These tentative conclusions need to be further investigated by examining more cultivars in each species and by concluding the drought phase for these eleven turfgrass now in the root column facility. 17. Significant drought avoidance and resistance differentials were found among the cultivars of bermudagrass and St. Augustinegrass. 18. The centipedegrass and zoysiagrass cultivars showed very good drought avoidance and resistance. 19. Most warm-season species having good drought avoidance and/or resistance had showed closed stomata or stomata blocked by wax layers. 20. The drought susceptible warm-season turfgrass species maintained open stomata and/or less wax accumulation across the stomata. 21. An early rate of stomatal closure after the onset of an internal water stress and the ability to form extensive wax layers across the stomata during water stress are two contributing mechanisms to drought avoidance which prevent water loss via transpiration. 22. Genetic diversity in terms of minimal maintenance adaptation to low nitrogen fertility regimes exists among bermudagrass cultivars and can be observed differentially as morphological, anatomical, and physiological plant parameters that can be statistically evaluated. 23. Leaf extension rate, internode length, visual quality when the nitrogen fertility rate is known, and tissue nitrogen content are useful parameters in identifying bermudagrass cultivars possessing low nitrogen stress tolerance. 24. An internal plant mechanism, such as a hormone, may be involved in partitioning available nitrogen between roots and shoots toe equally sustain survival until the available nitrogen is depleted. 25. Root mass relative to the shoot mass to be supported may be more important than root length in terms of survival under low nitrogen stress. 26. No final conclusions can be made at this time. However, considering the shoot proline level found during water stress and the shoot recovery of each plant, it appears that proline may contribute to the survival of plants during severe water stress. 27. The shoot proline content may be an indicator of proneness to drought stress injury. Those turfgrass species that are prone to drought injury usually exhibited more rapid proline accumulation than other species that are relatively less susceptible to drought injury. This can be partially explained by the relationship between the degree of leaf firing and the ratio between the shoot proline level before and after water stress. 28. When considering the closing of stomata relative to the ABA content, it appears that the rate of ABA synthesis may contribute to stomata closure in these turfgrasses. Additional studies are needed for final confirmation." |
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| Language: | English |
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| References: | 0 |
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| See Also: | See also related item, "Turfgrass water use rates" Grounds Maintenance, 21(1) January 1986, p. 60, 62, R=8054. R=8054
See also related item, "Spring root decline of warm season grasses" Grounds Maintenance, 21(1) January 1986, p. 92, 94, 138+, R=8055. R=8055
See also related item, "Comparative Rooting of Warm Season Turfgrasses" Grounds Maintenance, 21(9) September 1986, p. 64, R=13423. R=13423
See also related summary article, "Plant stress mechanisms", Annual Turfgrass Research Report [USGA/GCSAA], 1986, pp. 16-18, R=9246. R=9246 |
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| Note: | "Jointly Sponsored By: United States Golf Association and Texas Agricultural Experiment Station"
"October 31, 1986"
Appendices include full copies of 3 other abstracts or items
Pictures, b/w
Figures
Tables |
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http://archive.lib.msu.edu/tic/rpr/1986/9246, Texas A&M, Beard.PDF
Last checked: 03/28/2013
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MSU catalog number: b5288203 |
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