Herbage yield and composition of Kentucky bluegrass (Poa pratensis L.) cultivars under two harvest systems

Although Kentucky bluegrass (Poa pratensis L.) is a naturalized species commonly found in the permanent grasslands of eastern Canada, its contribution to sward output is not well defined. Six Kentucky bluegrass cultivars originating from Norway, Germany and North America, and a timothy (Phleum pratense L.) cultivar, were grown under two harvest systems at two locations to determine yield and herbage composition. All cultivars persisted over 3 production years. Dry matter yields of bluegrass cultivars were similar to those of timothy, ranging from 7.87 to 9.76 t ha(-1) in Charlottetown, Prince Edward Island, and from 3.64. to 4.79 t ha(-1) in Normandin, Quebec. Yields of broadleafed genotypes from Europe were superior in year 1. However, the warm and dry growing conditions of year 3 favoured the narrow-leafed genotypes. Mean tiller density of Kentucky bluegrass was 6440m(-2) ; timothy had a mean tiller density of 3040 m(-2). Forage quality attributes of Kentucky bluegrass were similar to those of timothy. Cultivar differences in fibre and mineral concentrations were consistent across years and locations and may provide selection criteria in breeding programs. Greater harvest frequency increased the total nitrogen concentration of herbage and tiller density but had no effect on yield. Kentucky bluegrass, is a persistent, valuable forage grass species with good potential for use in pasture and as conserved forage in eastern Canada.