Golf Course Management

MAR 2015

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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96 GOLF COURSE MANAGEMENT 03.15 Improved understanding and testing for salinity tolerance in cool-season turfgrasses Paul G. Johnson, Ph.D. B. Shaun Bushman, Ph.D. Water is a critical issue for sustainability of agriculture and urban areas in the North American West. Golf course superinten - dents are frequently asked, or forced, to use less irrigation water and/or to use water from lower-quality sources. Yet at the same time, rapid population growth requires these turf - grass areas to do more and be used by more people. Turfgrass with high quality, greater salt tolerance and greater drought tolerance is essential. Our research has focused on four questions: • Which plant measurements are most ef - fcient to select for salt tolerance? • What variation is present for salt toler - ance in perennial ryegrass (L olium pe- renne), Kentucky bluegrass (Poa pra- tensis) and alkaligrass (Puccinellia)? • Can alkaligrass be improved for turf - grass quality characteristics? • What genes can be used to differenti - ate between salt-tolerant and suscepti- ble grasses? It has been diffcult to fnd consistent salt tolerance in grasses due to interactions of climatic factors and variability in soil salin - ity. Our project is evaluating materials under controlled but representative conditions to gain a better understanding of the mecha - nisms of salt tolerance. In 2014 we focused on two parts of the (Report) project: (1) a repeat of a feld salinity experi- ment combining visual, physiological and mo- lecular evaluations of bluegrass and ryegrass entries; and (2) continued study of Puccinel - lia (alkaligrass) germplasm for turfgrass qual- ity traits. In 2014 we repeated feld salinity experi - ments that were also conducted in 2013. The salt treatments were applied overhead as irri - gation and were started mid-June with a salt concentration of 3 decisiemens/meter, in - creased to 6 decisiemens/meter in mid-July, then increased again to 9 decisiemens/meter in mid- August. This created soil salinity lev - els at 0.3 decisiemens/meter in control plots up to 12 decisiemens/meter in the salt-treated plots in August. As expected, salt treatments reduced turf - grass quality, but quality reductions were lower in 2014 than in 2013, likely because of generally cooler temperatures. Plant growth was impacted in 2014, ranging from 0% to greater than 50% reduction in growth due to salt stress. Studies of gene expression in salt- stressed plants compared to control plants is currently under way. In short, few data were obtained in 2014 on the alkaligrasses evaluated for turfgrass quality, since most did not survive the high temperatures in 2013. This gives us little con - fdence that these grasses will provide useful traits in the semi-arid western United States. Initial evaluation of Puccinellia showed some potential in turfgrass quality in cool condi - tions, but high temperatures in summer ap- pear most limiting to the species. However, we did observe consistent salt- tolerance trends in key Kentucky bluegrass lines. Gene sequences (alleles or paralogs) in - volved in cellular sodium and calcium chan- neling have been previously identifed and will be explored with root and shoot collec - tions in 2015. Paul G. Johnson (paul.johnson@usu.edu) is a professor in the department of plants, soils and climate at Utah State University, Logan, and B. Shaun Bushman is a research geneticist at the USDA-ARS Forage & Range Research Lab in Logan. Overall plot photograph on July 9, 2014. Visual symptoms of salt stress were mild at this midsummer date but growth was signifcantly inhibited. Photo by Paul G. Johnson

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