Auteur: McDonagh J., McEvoy M., Gilliland T.J. and O’Donovan M.
Jaar van uitgifte: 2015
Perennial ryegrass (Lolium perenne) is the most widely used ryegrass species for high-output pasture based dairy farms in Europe. Repeated selective breeding has enhanced dry matter (DM) productivity potential, elevated nutritive value and provided a large diversity of varieties adapted to variant growing conditions and farming practices. With renewed interest in white ryegrass-clover swards mixtures, there is a concern that sward interactions between perennial ryegrass varieties and white clover will have a significant effect on the dry matter yield performance of a recommended grass variety. The aim of this study was to establish if perennial ryegrass varieties re-rank in DM yield when sown with/without white clover at two nitrogen applications under intensive grazing. Eight perennial ryegrass varieties were sown with (+C) /without (-C) white clover. Swards received two levels of nitrogen 250 (HN) and 100 (LN) kg N ha‑1. Treatments were HN+C, HN-C, LN+C and LN-C. A significant nitrogen by clover interaction occurred because LN-C gave the lowest yield, but although high nitrogen increased both the with and without clover treatments, the highest yielding treatment was LN+C. Grass variety had a significant effect (P>0.001) on DM yield, but the ranking of the ryegrass varieties was unaffected by the imposed treatments and so represented a robust estimation of the relative DM production potential of each ryegrass variety. The inclusion of clover also did not affect the relative performance of the ryegrass varieties, indicating that any inter-species competitive interactions were not variety specific.