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Lisa L. Baxter and Brian M. Schwartz

The Beginning of a Legacy In 1946, Glen Burton and the USDA-ARS initiated a turfgrass breeding program in Tifton, GA to develop better bermudagrasses to replace sand putting greens or seeded varieties ( Burton, 1991 ). Researchers scouted golf

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Chengyan Yue, Jingjing Wang, Eric Watkins, Stacy A. Bonos, Kristen C. Nelson, James A. Murphy, William A. Meyer, and Brian P. Horgan

There has been a long history for turfgrass breeding programs to evaluate, develop, and introduce turfgrass cultivars with superior traits for use on lawns, sports fields, parks, roadsides, and other landscapes. Turfgrass breeding, like any other

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Hrvoje Rukavina, Harrison Hughes, and Randy Johnson

Development of a new turfgrass cultivar requires an evaluation of numerous traits as well as an understanding of environmental factors influencing those traits. Growth or ability to fill in gaps and time of fall dormancy (fall color retention) that indicates cold hardiness are important traits for turfgrasses. This study was initiated to characterize variation in saltgrass [Distichlis spicata L. (Greene)] growth and time of fall dormancy related to climatic and geographical factors at the source location (geographical location of clone origin). Growth traits and time of fall dormancy were measured on 52 saltgrass clones collected from 41 locations and established at one location (common garden) in Fort Collins, CO. Principal component analysis on the morphological traits extracted the first principal component that explained 78% of the variability. The first principal component and time of fall dormancy were related to climatic and geographical factors at the source locations. Variation in growth traits was related to seasonal climatic variables of summer drying and fall cooling that explained ≈50% of variability in morphological traits. Variation in time of fall dormancy was related to longitude of clone origin and minimum winter temperature. These two variables explained ≈60% of the total variability in time of fall dormancy. Information obtained in this study may help breeders identify the best environments for specific traits and suggests that cold tolerance could be a problem for some clones from western sources if established too far east.

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Eric Watkins and William A. Meyer

Recently, turfgrass breeders have developed many improved turf-type tall fescue (Festuca arundinacea Schreb.) cultivars. Due to the large number of cultivars currently available to turfgrass managers and researchers, we have classified turf-type tall fescue cultivars into six groups based primarily on several morphological measurements. This type of classification is important for turfgrass breeders because many breeding decisions are made based on observations in a spaced-plant nursery. The major objective of this study was to classify tall fescue cultivars and selections based on spaced-plant measurements and to then compare those results with turf performance. A spaced-plant nursery consisting of 36 cultivars and selections was established in September 1998 at Adelphia, N.J. Plant height, panicle length, flag leaf width and length, subtending leaf width and length, and subtending internode length were measured 10 days after anthesis in 1999 and 2000. Additionally, a turf trial was established at North Brunswick, N.J., that included the same 36 cultivars and selections. The turf plots were evaluated for several traits including overall turfgrass quality, density, and susceptibility to brown patch disease. Based on principal component analysis of morphological measurements, along with turf trial data, all cultivars and selections were assigned to one of six groups: forage, early-standard, standard, early semi-dwarf, semi-dwarf, and dwarf. In turf plots, the semi-dwarf, early-semi dwarf, and dwarf groups were the top-performing types in terms of overall turfgrass quality, and the forage and early-standard cultivars had the lowest overall quality ratings. The dwarf types did not perform well under summer stress, especially in terms of brown patch disease incidence. The results of this study suggest that when developing cultivars for higher maintenance situations, turf-type tall fescue breeders should focus on the development of semi-dwarf cultivars.

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Eric Watkins, Bingru Huang, and William A. Meyer

Tufted hairgrass [Deschampsia cespitosa (L.) Beauv.] is receiving increasing attention as a low-maintenance turfgrass for use in areas with reduced fertility or reduced sunlight. The objectives of this study were to examine physiological responses of tufted hairgrass to heat and drought stress and to distinguish whether better summer performance was related to better heat or drought tolerance. Four germplasm lines were chosen based on summer performance in field plots (two lines resistant to summer stress and two lines susceptible to summer stress) and were grown in growth chambers [14-hour photoperiod, 20/15 °C (day/night)]. Plants were exposed to either drought stress or heat stress (35/30 °C, day/night) for up to 49 days. Control plants maintained under normal conditions (20/15 °C, day/night, well watered) were included for both treatments. During the course of the study, single-leaf photosynthetic rate, photochemical efficiency, and relative water content were measured, and turf quality was visually rated. All parameters for all tufted hairgrass lines decreased under drought stress and heat stress, and the decline was more severe for summer stress-susceptible lines than for resistant lines. Lines that were previously considered resistant to summer stress exhibited superior photochemical efficiency under heat stress compared with the susceptible lines. When subjected to drought stress, the lines exhibited little or no differences in the measured parameters. These results suggest that observed variation in field summer performance among various tufted hairgrass germplasm lines may be mainly the result of their differences in heat tolerance. These results suggest that selecting for heat-tolerant germplasm could be important for further improvement in turf performance of tufted hairgrass during the summer.

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Brian Schwartz, Jing Zhang, Jonathon Fox, and Jason Peake

Heavily shaded environments often limit the performance and persistence of hybrid bermudagrass (Cynodon dactylon × C. transvaalensis), therefore a field-based shade study was performed to determine whether different mowing heights (0.5 and 1.5 inch) or two trinexapac-ethyl (TE) growth regulator management treatments (control and 2 oz/acre) allow either ‘TifSport’ or ‘TifGrand’ hybrid bermudagrass to persist under 77% shade. Turfgrass quality (TQ), green cover, normalized difference vegetation index (NDVI), and dark-green color index (DGCI) were evaluated on the two cultivars under a shade structure in Tifton, GA, during 2010 and 2011. Neither of the cultivars maintained acceptable TQ throughout the entire year under 77% shade, although ‘TifGrand’ displayed adequate TQ at the higher mowing height (1.5 inch) and demonstrated more shade tolerance than ‘TifSport’, as indicated by TQ, green cover, and NDVI. The TE application did not enhance the turf performance of ‘TifSport’ under 77% shade when mowed at 0.5 inch, but it improved turf performance of ‘TifGrand’ at the same height. The effect of TE application was cultivar and mowing height dependent under this heavily shaded environment, which warrants future study to determine the best management practices of these cultivars as well as continued efforts to develop new, shade-tolerant bermudagrass hybrids.

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Wenjing Pang, John E. Luc, William T. Crow, Kevin E. Kenworthy, Robert McSorley, and Robin M. Giblin-Davis

. Accessions with larger root systems tend to be more tolerant, which might be potentially useful for turfgrass breeding and development for host tolerance against nematodes. This is the first report of sting nematode responses on African bermudagrass and

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Lisa A. Beirn, William A. Meyer, Bruce B. Clarke, and Jo Anne Crouch

became apparent that leaf spot–resistant cultivars such as Merion were highly susceptible to stem rust disease caused by the fungus P. graminis ( Ray, 1953 ). It is now common practice for turfgrass breeding programs to evaluate new sources of germplasm