Genetic Variability of Traffic Tolerance and Surface Playability of Bermudagrass (Cynodon spp.) under Fall Simulated Traffic Stress

Bermudagrasses (Cynodon spp.) are the most preferred turfgrass species for athletic fields in the southern and transition zones of the United States. Developing and using bermudagrasses with superior traffic tolerance and surface playability under trafficked conditions benefits turfgrass managers, athletes, and sport organizations. A 2-year field study was conducted in Stillwater, OK, to quantify the genetic variability of traffic tolerance and surface playability from a population composed of two commercially available and 87 experimental interspecific hybrid bermudagrasses under fall simulated traffic stress. The experiment design was a randomized complete block design with three replications. Plots were subjected to 60 simulated cleat traffic events for 6 weeks in the fall of 2019 and 2020 using a Baldree traffic simulator. Bermudagrasses were evaluated for turfgrass quality (TQ), normalized difference vegetation index (NDVI), fall percent green cover (FPGC), shear strength (SS), and surface hardness (SH) after 3 and 6 weeks of traffic. Spring green-up percent green cover (SGPGC) was evaluated in the spring of 2020 and 2021. Except for SH, significant entry effects were found for all parameters and reliability estimates were moderate to high (i2 = 0.49 to 0.68) under simulated trafficked conditions. Experimental entries 17-4200-19X13, 17-4200-19X9, 17-4200-36X19, 17-5200-4X11, 18-7-2, 18-7-6, 18-8-2, 18-8-3, 18-8-7, 18-9-2, OSU1101, and OSU1664, and TifTuf® had excellent traffic tolerance. Entries 18-8-7, OSU1101, OSU1675, TifTuf®, and Tahoma 31® demonstrated high SS. There was a large group of entries that had consistent early spring green-up across both years, including Tilin#5, 18-9-8, OKC1221, OSU1257, OSU1318, OSU1337, OSU1406, OSU1439, OSU1651, OSU1675, Tahoma 31®, and TifTuf®. OSU1101 was the entry ranking in the top statistical grouping most often throughout the study. Findings illustrated the possibility of improving traffic tolerance and SS through breeding and using phenotypic selection could reliably select bermudagrass genotypes with improved traffic tolerance and SS in the transition zone.