Shade effects on overseeded bermudagrass athletic fields: I. Turfgrass coverage and growth rate

Shade from athletic stadium structures can be a significant deterrent to turfgrass performance. The objective of this study was to determine the daily light requirements of an overseeded or non-overseeded bermudagrass (Cynodon spp.) turf maintained to simulate an athletic field. An experiment was established in 2013 on a mature bermudagrass [Cynodon dactylon (L.) Pers. cv. Riviera] turf that was either overseeded with perennial ryegrass (Lolium perenne L.) or non-overseeded. Plots were re-seeded with ryegrass each fall, but ryegrass was allowed to transition without chemical removal. Shade structures were installed to create four light level treatments including a full-sun control (0% shade) and 30%, 60%, or 90% light-reducing shade cloth. Quantum light sensors were mounted under each shade treatment and photosynthetic photon flux density (PPFD) was continuously measured and a daily light integral (DLI) calculated (mol PPFD m–2 d–1). The 2-yr, average DLI values for shade treatments were 40.8 (0% shade), 26.2 (30% shade), 14.8 (60% shade) and 3.3 (90% shade) mol PPFD m–2 d–1. A range of growth and performance data were collected, including turfgrass coverage, clipping yields and leaf elongation rates. Overseeded and non-overseeded bermudagrass failed to persist when 90% shade (DLI = 3.0 mol m–2 d–1) was imposed. Non-overseeded bermudagrass required a higher DLI (26 mol m–2 d–1) to persist compared to overseeded bermudagrass (DLI = 21.8 mol m–2 d–1), primarily due to the enhanced shade tolerance of perennial ryegrass. However, the long-term effects of shade began to decrease the quality of the overseeded turf by the end of the second year of the study. These data provide sports field managers with threshold light requirements for both overseeded and non-overseeded bermudagrass turf.