Turf performance of seeded and clonal bermudagrasses under varying light environments

Abstract

Bermudagrass (Cynodon spp.) demonstrates several desirable attributes that contribute to its widespread popularity for use as a turfgrass. However, a significant limitation to more widespread usage is the poor shade tolerance of bermudagrass relative to other species (e.g., Zoysia spp.). Improvement of this trait through recurrent selection of seeded-type cultivars may contribute to increasing the adaptive range of this relatively important turfgrass. A three-year field study was conducted to evaluate the relative shade tolerance of ten commercially-available or experimental bermudagrass cultivars, including seeded-type and clonally-propagated genotypes, in Stillwater, OK. Plots were established in three blocks representing three light environments: full sun, moderate shade (40% of full sun), or severe shade (20% of full sun). Bermudagrass cultivars were evaluated for visual turf quality, normalized difference vegetation index (NDVI), visual spring green-up, and visual plant density. A turf performance index (TPI) was used to develop a relative ranking of shade tolerance among cultivars tested, and a minimum daily light integral (DLI) for each cultivar was calculated using visual turf density as the criterion. Results indicate ‘Celebration’ was the most shade tolerant cultivar requiring 13 mol m−2 d−1 photosynthetically active radiation (PAR) from June through September, while ‘Patriot’ was the least shade tolerant cultivar requiring 26 mol m−2 d-1 PAR. Other cultivars were intermediate in shade tolerance having a minimum DLI ranging from 17 to 21 mol m−2 d−1 PAR. Shade tolerance of experimental cultivars was similar to existing commercially-available cultivars suggesting further selection or breeding effort is required to improve this trait.