GROUND COVER RESPONSE TO MOWING HEIGHT OF TURFGRASS MONOCULTURES AND BINARY MIXTURES

The purpose of this study was to describe and quantify the effect of mowing on the ground cover of turfgrasses growing in pure stands and various binary mixtures. Three types of turfgrass were chosen: Perennial ryegrass (Lolium perenne L.), creeping bentgrass (Agrostis stolonifera L.) and Smooth-stalked meadow-grass (Poa pratensis L.). Three pure stands and nine binary mixtures were sown with the same total number of caryopsis (7000). The proportions of each species in mixtures were defined according to the de Wit model (25%/75%, 50%/50%, 75%/25%). Pure stands and mixtures were mowed at three heights (10, 25 and 40 mm). The Braun-Blanquet scale was used to estimate the cover of each turfgrass species. A spatial survey was carried out with a squared quadrat. These data were collected throughout two years. For all mixtures a better ground cover was observed with 10 mm mowing height for creeping bentgrass, 25 mm for Smooth meadow-grass and 40 mm for perennial ryegrass. Spatial dynamics of the cover was also a function of (i) the evolution of aggressiveness of one species towards the other and (ii) the growth form that explains the spatial tactics (phalanx, guerrilla) of each associated species. For example, Smooth-stalked meadow-grass was a very slow growing species at the early stages, thus it did not cover a large surface even in 75-25% mixtures. In contrast, perennial ryegrass was an aggressive species during the sward establishment compared to Smooth-stalked meadow-grass. For all the binary mixtures, creeping bentgrass was a very competitive partner compared to the other two species. These data should allow us to build a model of spatial dynamics in short habit communities such as a turf.