Shade Effects on Athletic Field Playing Characteristics of Overseeded and Non-Overseeded Bermudagrass.

In many athletic stadiums around the world, reduced light levels from the stadium structure can significantly reduce turfgrass quality and playing characteristics. In most warm-weather stadiums, the primary surface is bermudagrass which is commonly overseeded with perennial ryegrass to provide a winter and spring playing surface. The objective of this study was to examine the effects of four shade levels on turfgrass quality and playing characteristics of overseeded and non-overseeded bermudagrass (cv. Riviera). Shade levels included a non-shaded control and shade treatments which blocked 30%, 60%, and 90% of ambient light. These shade levels resulted in average daily PAR loads of 45.1, 29.6, 16.7, and 4.7 mol PAR / m2 / day, respectively.  Data collection included both quality and playability characteristics. The effects of shading became obvious as the study continued into early summer, with the 90% shade plots losing almost all cover and the 60% shade plots losing up to 40% of coverage through mid-summer. The 30% shade plots had a slight decline in turfgrass coverage, although, still retained close to 90% coverage. Based on these results, a minimum daily light load of approximately 30 mol PAR / m2 / day is needed to sustain Riviera bermudagrass at or near 100% coverage. In the overseeded plots, the only shade treatment that caused a significant reduction in turfgrass coverage was the 90% shade treatment (4.7 mol PAR / m2 / day). There was a significant decrease in the amount of bermudagrass present in the overseeded plots in mid-summer, suggesting that increased shading was causing a shift in population from the warm-season bermudagrass to the cool-season perennial ryegrass. In both overseeded and non-overseeded plots, rotational resistance (traction) decreased even with modest levels of shade , which is likely correlated to a decrease in turfgrass density.