Daily light integral requirements of warm‐season turfgrasses for golf course fairways and investigating in situ evaluation methodology

Abstract

AbstractDetermining daily light integral (DLI) requirements for turfgrass systems has been an effective method to quantify photosynthetically active radiation (PAR) necessary to maintain quality turfgrass in a research setting. However, there has been little research estimating DLI requirements of popular turfgrass cultivars of zoysiagrass [Zoysia matrella(L.) Merr. andZ. japonicaSteud.], hybrid bermudagrass [Cynodon dactylon(L.) Pers. ×C. transvaalensisBurtt Davy], and common bermudagrass [C. dactylon(L.) Pers.] used for teeing grounds and fairways on golf courses. The objective of this research was to (a) determine minimum DLI requirements of two zoysiagrasses, ‘Cavalier’ (Z. japonica) and ‘Meyer’ (Z. matrella), and two bermudagrasses, common bermudagrass (cultivar unknown) and ‘Astro‐DLM’ hybrid bermudagrass; and (b) investigate methodology in rapidly estimating DLI requirements in situ at area golf courses for the same cultivars. Cultivars were evaluated under 22, 40, 60, and 90% shade in a field research setting over two seasons from August through October 2016 and May through October 2017. Turfgrass quality continued to decline over the 2‐yr trial, emphasizing importance of multi‐year evaluations encompassing cumulative effects of shade on turfgrass. Estimated minimum DLI requirements for turf quality of Astro‐DLM hybrid bermudagrass, common bermudagrass, Cavalier zoysiagrass, and Meyer zoysiagrass were 20.4, 25.9, 15.0, and 21.1 mol m−2d−1, respectively. In situ evaluations at golf course sites accurately estimated DLI requirements for three of four cultivars in comparison to those obtained in field research setting. Established minimum DLI requirements determined for cultivars in this study provide a baseline for site specific turfgrass selection.