Comparison of Italian Ryegrass and Meadow Fescue with F2, F3, and F4 Hybrids of Both Grass Species

Summary In forage-grass breeding there is an increasing interest in hybrids of Italian ryegrass (Lolium multiflorum Lam.) and meadow fescue (Festuca pratensis Huds.). The objective of this study was to investigate some agronomic properties of such Festulolium hybrids with special reference to the question of whether these hybrids change from one generation to the next. In a pot experiment with four levels of nitrogen fertilization, Italian ryegrass and meadow fescue as well as F₂, F₃, and F₄ hybrids of the two grass species were examined for 2 years. In each year four cuts were taken. All the F₂, F₃, and F₄ hybrids were descendants of a single F₁ plant. Therefore, some inbreeding effects must be taken into account in spite of open pollination of the hybrids. The fertility of the hybrids increased from one generation to the next. In the first year, after the grasses were sown in spring, meadow fescue produced substantially lower yields than Italian ryegrass at the higher nitrogen doses and died off almost completely at the highest nitrogen level. The yields of the hybrids exceeded those of meadow fescue and, at lower nitrogen supply, even those of Italian ryegrass. Very high nitrogen doses were tolerated much better by the hybrids than by meadow fescue but not quite as well by the hybrids as by ryegrass. In the second year, after wintering, all grasses formed culms, with Italian ryegrass showing the most abundant culm development. The hybrids outyielded meadow fescue and ryegrass in the second year nearly without exception. In general, the yields of the hybrids were distributed more evenly among the various cuts than were those of Italian ryegrass. In both years, the hybrids mostly gave noticeably higher yields than either of the parent species. Within the different nitrogen levels, the crude-protein content was lower and the content of water-soluble carbohydrates usually was higher as the yield of dry matter increased. The crude-fiber content of the hybrids often proved to be somewhat higher than that of Italian ryegrass but not higher than that of meadow fescue. In regard to yield, quality, and response to nitrogen, no well-defined changes occurred with the succession of hybrid generations. There was no evidence that the hybrids reverted to one of the parent species. These results may encourage plant breeders to direct greater attention to such hybrids.