Differential Sowing Time of Turfgrass Species Affects the Establishment of Mixtures

Abstract

Kentucky bluegrass (Poa pratensis L.) is often poorly established when sown in turfgrass seed mixtures with slender creeping red fescue (Festuca rubra L. ssp. litoralis Vasey) and perennial ryegrass (Lolium perenne L.), possibly because of its slow emergence and slow seedling growth. This study investigated the effect of sowing Kentucky bluegrass earlier than red fescue and perennial ryegrass on the botanical composition of the established turfgrass. In field experiments established during 2 yr, red fescue and perennial ryegrass were sown at weekly intervals from zero to 35 d [0–679 degree‐days (°days) with a base temperature of 0°C] after Kentucky bluegrass had been sown in the same plot. Nine or twelve months after establishment, the botanical composition was estimated. When the species were sown simultaneously, Kentucky bluegrass only constituted 3 to 30% of the tillers, although the species constituted 50 to 59% of the viable seeds of the seed mixture. Delayed sowing of red fescue and perennial ryegrass significantly improved the establishment of Kentucky bluegrass, i.e., the percentage of tillers could be increased by up to 0.08% for every °day Kentucky bluegrass was sown before red fescue and perennial ryegrass. There was a corresponding negative effect on the percentage tillers of red fescue and primarily perennial ryegrass. In certain cases, the relationship between percentage tillers and difference in sowing time was better described by a nonlinear function, indicating an increasing effect when difference in sowing time was large.