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  • Author or Editor: Mingying Xiang x
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Turfgrass managers are using reclaimed water as an irrigation resource because of the decreasing availability and increasing cost of fresh water. Much attention, thereby, has been drawn to select salinity-tolerant turfgrass cultivars. An experiment was conducted to evaluate the relative salinity tolerance of 10 common bermudagrasses (Cynodon dactylon) under a controlled environment in a randomized complete block design with six replications. ‘SeaStar’ seashore paspalum (Paspalum vaginatum) was included in this study as a salinity-tolerant standard. All entries were tested under four salinity levels (1.5, 15, 30, and 45 dS·m−1) consecutively using subirrigation systems. The relative salinity tolerance among entries was determined by various parameters, including the normalized difference vegetation index (NDVI), percentage green cover determined by digital image analysis (DIA), leaf firing (LF), turf quality (TQ), shoot vertical growth (VG), and dark green color index (DGCI). Results indicated that salinity tolerance varied among entries. Except LF, all parameters decreased as the salinity levels of the irrigation water increased. ‘Princess 77’ and ‘Yukon’ provided the highest level of performance among the common bermudagrass entries at the 30 dS·m−1 salinity level. At 45 dS·m−1, the percent green cover as measured using DIA varied from 4.97% to 16.11% among common bermudagrasses, where ‘SeaStar’ with a DIA of 22.92% was higher than all the common bermudagrass entries. The parameters LF, TQ, NDVI, DGCI, VG, and DIA were all correlated with one another. Leaf firing had the highest correlation with other parameters, which defined its value as a relative salinity tolerance measurement for common bermudagrass development and selection.

Full access

There is a growing trend of cultivating hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy] on golf course putting greens in the transition zone because of its excellent quality in the summer months, coupled with less pesticide input than creeping bentgrass (Agrostis stolonifera L.). However, the long-term success of bermudagrass putting greens is hindered by low temperatures in winter months, particularly in the transition zone. To address this issue, in addition to genetic improvement for cold hardiness through the development of new cultivars, effective management approaches are necessary to enhance the winter survival of putting green–type bermudagrass. The objective of this study was to investigate the relative freeze tolerance of four bermudagrasses and the effects of raising mowing height on the freeze tolerance of putting green–type bermudagrasses. In this study, two experimental putting green–type bermudagrasses (11X2 and OKC0805) along with cultivars TifEagle and OKC3920 were tested at two mowing heights (3.2 vs. 6.4 mm) at freeze temperatures that ranged between –4 and –11 °C. The lethal temperature to kill 50% of the population (LT50) as well as regrowth vigor during recovery were evaluated. Variety ‘OKC3920’ demonstrated enhanced freeze tolerance compared with ‘TifEagle’ at both mowing heights. Increasing the mowing height from 3.2 mm to 6.4 mm improved freeze tolerance for most genotypes tested in this study. After exposing the grasses to –8 °C for 1 hour, genotypes such as 11X2 exhibited better regrowth vigor and demonstrated a faster recovery. This study suggests that golf course managers can enhance winter resilience of bermudagrass putting greens by selecting genotypes strategically with superior freeze tolerance and raising mowing heights in the fall acclimation process.

Open Access

Bermudagrass (Cynodon sp.) is a highly productive, warm-season, perennial grass that has been grown in the United States for turfgrass, forage, pasture, rangeland, and roadside use. At the same time, many bermudagrass production and reclamation sites across the United States are affected by soil salinity issues. Therefore, identifying bermudagrass with improved salinity tolerance is important for successfully producing bermudagrass and for reclaiming salt-affected sites with saline irrigated water. In this project, the relative salinity tolerance of seven clonal-type bermudagrass was determined, including industry standards and an Oklahoma State University (OSU) experimental line. The experiment was conducted under a controlled environment with six replications of each treatment. Seven bermudagrass entries were exposed to four salinity levels (1.5, 15, 30, and 45 dS·m−1) consecutively via subirrigation systems. The relative salinity tolerance among entries was determined by normalized difference vegetation index (NDVI), digital image analysis (DIA), leaf firing (LF), turf quality (TQ), shoot dry weight (SW), visual rating (VR), and dark green color index (DGCI). Results indicated that there were variable responses to salinity stress among the entries studied. As salinity levels of the irrigation water increased, all evaluation criterion decreased, except LF. All entries had acceptable TQ when exposed to 15 dS·m−1. When exposed to 30 dS·m−1, experimental entry OKC1302 had less LF than all other entries except ‘Tifway’, while ‘Midlawn’ showed more LF than all the entries. Leaf firing ranged from 1.0 to 2.7 at 45 dS·m−1, where ‘Tifway’ outperformed all other entries. At 45 dS·m−1, the live green cover as measured using DIA ranged from 3.07% to 24.72%. The parameters LF, TQ, NDVI, DGCI, SW, and DIA were all highly correlated with one another, indicating their usefulness as relative salinity tolerance measurements.

Free access

Traffic injury caused by foot- or athlete-surface interaction is one of the most critical problems athletic field managers face in maintaining the surface playability and aesthetic quality of athletic fields. Bermudagrass (Cynodon spp.) is the most widely used turfgrass species on athletic fields in the transitional climatic zone. A 2-year field study was conducted to evaluate nine bermudagrass cultivars for their persistence and surface playability under simulated fall cleat traffic. The experiment was conducted in Stillwater, OK, on a natural loam soil. Treatments were arranged as a split-block design with three replications. Traffic was applied for 6 weeks in Fall 2019 and 2020 using a Baldree traffic simulator, which generated 10 traffic events per week; each traffic event resulted in 678 cleat marks/m2. ‘Bimini’ was generally found to be the most persistent grass under traffic for aesthetic properties, and ‘Astro’ and ‘Tifway’ were the least persistent. Surface playability was affected by simulated traffic stress as shear strength (SS) declined and surface hardness (SH) increased, over time. ‘Bimini’ had greater SS than ‘Astro’ and ‘OKC1131’ (Tahoma 31®) by 1.9 and 1.4 N·m, respectively. SS of ‘DT-1’ (TifTuf®) and Tahoma 31 and SH of ‘OKC1134’ (NorthBridge®) were least affected by simulated traffic stress. Overall, surface playability characteristics of NorthBridge, ‘Bimini’, ‘OKC1119’ (Latitude 36®), TifTuf, Tahoma 31, and ‘Riley Riley’s Super Sport’ (Celebration®) were least affected by traffic. Findings illustrate bermudagrass cultivars can vary in visual persistence and surface playability.

Open Access

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 (i 2 = 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.

Open Access