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| Web URL(s): | http://archive.lib.msu.edu/tic/rpr/2000/72116,%20U%20RI,%20Hull.PDF
Last checked: 02/06/2013
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| Publication Type:
| Report |
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| Material Type: | Manuscript |
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| Monographic Author(s): | Hull, Richard J.; Jiang, Zhongchun; Ruemmele, Bridget; Bushoven, John T. |
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| Author Affiliation: | Hull: Principal Investigator, Professor of Plant Physiology; Jiang: Postdoctoral Research Associate; and Ruemmele: Associate Professor, Turfgrass Improvement |
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| Monograph Title: | Increasing the Nitrogen Use Efficiency of Cool-Season Turfgrasses by Regulating Nitrate Metabolism: [Annual USGA Report], 2000. |
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| Publishing Information: | [Kingston, Rhode Island]: University of Rhode Island |
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| # of Pages: | 13 |
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| Collation: | [13] pp. |
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| Abstract/Contents: | "Among the objectives of the USGA's research grants program is the development of turfgrasses and a strategy for managing them that will significantly reduce the amount of fertilizer required to maintain high quality turf under golf course conditions. The achievement of this objective will lower the cost of turf management and futher reduce the already minimal contricutions golf courses make to ground and surface water contamination. This project has concentrated on increasing our understanding of the metabolic basis for efficient nitrogen use by the perennial cool-season turfgrasses creeping bentgrass and perennial ryegrass. We have attempted to understand the factors contributing to nitrogen use efficiency in turfgrasses and manipulate these factors in such a way that the need of turf for nitrogen fertilizers will be reduced. We have concentrated on the physiology of biomass partitioning btween roots and shoots. A turfgrass that can allocate more of its photosynthetic resources toward root growth will have a larger root system that will be better able to absorb nutrients and water from a larger soil volume. Such turfgrasses will be better able to tolerate drought conditions and derive a larger portion of their nitrogen requirements from that provided by organic matter cycling within the soil. Nitrogen is available to turfgrass roots primarily in the form of nitrate (NO3-). Nitrate is produced in the soil when organic matter is metabolized by microbes, releasing its nitrogen as the ammonium (NH4+) that in turn is oxidized by other microbes to NO3-. Thus, regardless of the nitrogen source applied, that nitrogen will be available to the turf as nitrate. This NO3- is highly mobile and can leach with rainwater out of the soil and potentially contaminate ground water. The best protection of ground water quality is a dense root system that will absorb NO3- to supply the needs of the grass for nitrogen and sustain those roots throughout the year for continued NO3- uptake. We are examining the capacity of nine cultivars each of perennial ryegrass and creeping bentgrass to absorb NO3- and metabolize it within the grass plant in order to test our hypothesis that quality turf is more likely to occur when turfgrasses metabolize NO3- primarily in their roots with relatively little NO3- transported to and metabolized in the shoots. Our research has shown that cultivars of perennial ryegrass and creeping bentgrass allocate most of their photosynthetic resources to shoot growth and little to roots. These same grasses also metabolize most of the NO3- they absorb from the soil in their shoots which may explain their priority of shoot growth over root production. Generally, creeping bentgrass metabolizes more NO3- in its roots and also partitions a greater portion of its total biomass to root growth than does perennial ryegrasses. We have also observed that perennial ryegrass absorbs nitrate more rapidly from the soil than does creeping bentgrass but much of this nitrate is transported to and metbolized in leaves. This alone could explain why perennial ryegrass produces more shoot growth and less root growth. In perennial ryegrass, we have also observed a positive and significant relationship between NO3- metabolism in roots and the amount of roots produced. This may explain how bentgrasses, that absorb nitrate more slowly and metabolize more of it in the roots thereby promoting greater root growth, can sustain themselves when maintained as a very closely mowed turf. These findings have supported our theory linking root-centered NO3- metabolism and greater root growth with less shoot production. Research proposed for the future of this project will concentrate on further testing our hypothesis and formulating turf management strategies that can use these findings to make present turfgrasses more efficient in their use of soil nitrogen." |
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| Language: | English |
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| References: | 0 |
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| See Also: | See also related summary article, "Increasing the nitrogen efficiency of cool-season turfgrasses by regulating nitrate metabolism", 2000 Turfgrass and Environmental Research Summary [USGA], 2000, p. 15, R=72116. R=72116 |
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| Note: | Also appears as pp. 767-779 in the USGA Turfgrass Research Committee Reporting Binders for 2000
"November 2000"
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