Golf Course Management

NOV 2014

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

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80 GOLF COURSE MANAGEMENT 11.14 CUTTING EDGE Teresa Carson Heritability estimates for morphological variation and rust response of Zoysia The most commonly used species of zoy- siagrass are Zoysia matrella and Z. japonica, which have differing leaf textures, growth habits and seed head traits. Zoysia japonica has a medium-coarse leaf texture, upright growth and longer seed heads, while Z. matrella has a fner leaf texture, more compact growth habit and shorter seed heads. Hybrids between these species are viable and have been evaluated for improved tolerance to biotic and abiotic stress factors. Heritability values have been estimated in zoysiagrass for coverage, density, quality, genetic color, fall dormancy, seed head density, and limited disease and nematode re - sistance. Heritability and segregation of other traits have not been estimated for genetic pop - ulations of Z. matrella and Z. japonica. Large patch disease development was compared on 50 germplasm lines that were inoculated and incubated in a controlled walk-in chamber. Nineteen lines with different leaf textures and disease responses were used to develop a ge - netic population. The narrow-sense heritabil- ity of stem and leaf color, leaf texture, growth habit, raceme length and number, foret color and rust response were estimated in progeny from six families. Variation was observed for all traits. Heritability estimates were calcu - lated using ASReml software. High herita- bility was observed for leaf width, indicating that, in this population, leaf width is mainly infuenced by genetic effects. Moderate heri - tability estimates were obtained for stem color, fowering initiation and rust response. Rela - tively low heritability values were obtained for leaf color, growth habit, raceme length and foret color, indicating that these traits, in this population, are infuenced more by environ - mental factors. Overall, these results indicate that the traits are under genetic control and that improvements can be obtained through hybridization and selection of desirable in - dividuals. — Norma Cristina Flor; Kevin E. Ken- worthy, Ph.D.; Philip Harmon, Ph.D.; and Patricio Munoz, University of Florida, Gainesville, Fla. Shade tolerance evaluation of South African bermudagrass germplasm Bermudagrass (Cynodon species) is one of the most commonly grown turfgrass genera in the southern United States, having excellent drought tolerance but poor tolerance to shade. Developing cultivars tolerant to shade would allow bermudagrass to be used in areas where trees dominate the landscape. In this study, nine accessions collected from Pretoria, South Africa, were evaluated for their ability to grow under shade. These accessions and the culti - vars Celebration, Tifgrand and Tifway were evaluated under 0%, 63% and 80% shade during 2011-2012. For both years, signifcant differences among shade levels and genotypes, and the interaction of the two, were observed. As expected, the progression from 0% to 63% to 80% shade reduced normalized difference vegetation index (NDVI), percent turfgrass cover and turf quality readings for all acces - sions. Some genotypes, however, were able to maintain adequate quality and aggressive - ness under low-light conditions. Celebration, WIN10F and STIL03 performed better than all other entries under the selected shade treat - ments (63% and 80%) across both years of the study. Overall, our results indicate that there are promising genotypes among the bermu - dagrass materials collected from South Africa. These accessions represent additional sources of shade tolerance to be used in bermuda- grass breeding. — Jeffrey C. Dunne and Susana R. Milla-Lewis, Ph.D., North Carolina State University, Raleigh, N.C. Teresa Carson ( is GCM 's science editor. Photo by N.C. Flor Photo by S.R. Milla-Lewis

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