Golf Course Management

JUN 2019

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06.19 GOLF COURSE MANAGEMENT 73 erally had similar drought performance, with water content and membrane stability being good indicators of drought performance. In comparison to paspalums, bermudagrasses generally were better able to regulate energy metabolism and used osmotic adjustment to greater degrees, potentially indicating species-specific drought responses. Osmotic adjustment occurs when solutes accumulate within the cells, which helps the plant keep water in the cells and protect against drought. Tif Tuf consistently used osmotic adjustment mechanisms in response to drought. Conclusions Variations in drought tolerance were found among a collection of bermudagrass and seashore paspalum cultivars. Tif Tuf ber- mudagrass was the top performer across both years, and it is likely that the exceptional lev- els of drought tolerance seen in Tif Tuf are the result of several stress tolerance mecha- nisms working together. However, osmotic adjustment is likely to be an essential com- ponent of the observed drought tolerance. Solutes that accumulate during drought as a part of osmotic adjustment, including sugars and amino acids, protect the cell by helping maintain cellular water content. Although the most tolerant grass was a bermudagrass and the least tolerant was a seashore paspalum cultivar, the top-perform- ing seashore paspalum cultivar, UGA 1743, had drought tolerance levels on par with some bermudagrasses, demonstrating that a range of drought tolerance exists in both species. Mechanisms responsible for drought tolerance will continue to be explored as more improved cultivars with high levels of stress tolerance are developed. Funding …is research was supported by funding from the USDA National Institute of Food and Agriculture Specialty Crop Research Ini- tiative and Georgia Agricultural Experiment Stations. Acknowledgments …is research was previously published as "Drought performance and physiological responses of bermudagrass and seashore pas- palum" by David Jespersen, Monique Leclerc, Gengsheng Zhang and Paul Raymer in Crop Science 59:778-786 (2019). doi:10.2135/crop- sci2018.07.0434 David Jespersen (djesper@uga.edu) is an assistant pro- fessor, Monique Leclerc is Regents professor, and Paul Raymer is a professor in the Department of Crop and Soil Sciences, College of Agriculture and Environmental Sci- ences Campus, University of Georgia, Griffin, Ga. Relationships of soil analysis, turf quality and shoot analysis of Kentucky bluegrass under effluent water irrigation on golf courses Yaling Qian, Ph.D. Yuhung Lin Golf courses in the western United States are increasingly being irrigated with effluent water. Limited research information is avail- able regarding the degree of accumulation of different minerals or salts in turfgrass shoots when effluent water is used for irrigation. More research is needed to determine the rela- tionships among soil salinity parameters, turf quality and shoot mineral concentrations. Research was conducted on eight golf courses in the semiarid front range of Col- orado, including three courses with effluent water irrigation for 10 years, three courses with effluent water irrigation for 18 to 26 years, and two courses with surface water for irrigation for 15 and 18 years. Turf quality of Kentucky bluegrass (Poa pratensis), the most widely used turfgrass species in the United States, was evaluated on 25 roughs from the above-mentioned golf courses. Concurrently, Kentucky bluegrass shoot samples and soil samples were collected from these sites. Shoots of Kentucky bluegrass were analyzed for mineral concentrations of sodium (Na), calcium (Ca), magnesium (Mg), potassium (K), chloride/chlorine (Cl), boron (B), sulfur (S), phosphorus (P), man - ganese (Mn), iron (Fe) and zinc (Zn). Elec- trical conductivity (EC) and sodium absorp- This research was funded in part by the United States Golf Association. tion ratio (SAR) of soil saturated paste were determined. Kentucky bluegrass at the surface-water irrigation sites and the 10-year effluent water irrigation sites had similar turf quality rat- ings. …e average turf quality of Kentucky bluegrass irrigated with effluent water for 18 to 26 years was lower than that of the sur- face-water irrigation group and of the 10- year effluent water irrigation group (Table 1). Sodium accumulation in the shoots was found in all courses irrigated with effluent water. Mean sodium ion (Na+) concentration in Kentucky bluegrass shoots in milligrams/ kilogram was 329 for the surface-water ir- rigation group; 1,427 for the 10-year efflu- ent water irrigation group; and 3,256 for the 18+-year effluent water irrigation group. Ef- fluent water irrigation increased clipping sodium by 4.3 times in the 10-year group This image shows the difference between Tifway (left) and TifTuf (right) bermudagrass during the 2016 drought trial. TifTuf was the best performer throughout the trial. Photo by David Jespersen

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