Effect of seeding rate on seed production of perennial ryegrass after establishment with a grain companion crop in the Peace River region of north-western Canada

A field study in the Peace River region of north-western Canada evaluated t he effect of seeding rate on the seed yield and quality of perennial ryegra ss (Lolium perenne L.) in the year after establishment with a grain compani on crop. Each of two sites was sown with 70 kg ha(-1) barley (Hordeum vulga re L.) and under-sown, in 30-cm rows, with three cultivars (All*Star, Barcl ay and Repell) of diploid perennial ryegrass at seeding rates of 150, 300, 600, 1200, 2400 and 4800 viable seeds m(-2). During the establishment year of the perennial ryegrass, the grain yield of the barley companion crop was comparable to commercial yields for the region. Time of seed maturity, see d yield and thousand-seed weight of perennial ryegrass were not significant ly (P less than or equal to 0.05) affected by the seeding rate, but were by cultivar. There was a significant (P less than or equal to 0.01) seeding r ate x cultivar interaction for fertile tiller density and specific seed wei ght. Seed dockage differed significantly (P less than or equal to 0.001) am ong cultivars (16.7-27.9%) and increased with seeding rate (19.8-24.2%), an d the germination capacity of the harvested seed was unaffected by seeding rate or cultivar. Grass seed yield was positively associated with fertile t iller density for each cultivar (r = 0.454***, n = 72 for All*Star; r = 0.3 64***, n = 72 for Repell; and r = 0.719***, n = 72 for Barclay). Compared w ith the other cultivars, Barclay matured 13-15 d later, had the lowest dens ity of fertile tillers (1330 m(-2)), the highest seed dockage (27.9%) and t he lowest seed yield (345 kg ha(-1)). All*Star had the highest seed yield ( 774 kg ha(-1)), the lowest seed dockage (16.7%), and the highest thousand-s eed weight (1.55 g). Repell was intermediate in seed yield (633 kg ha(-1)) but similar to All*Star, rather than Barclay, in other characteristics. The later maturity, creeping habit and prostrate stature of Barclay may have r educed its ability to produce fertile tillers and seed as efficiently as th e other two cultivars at this northern latitude. In the Peace River region, there is potential for under-seeding a spring grain crop with perennial ry egrass for the production of successive harvests of grain and grass seed, p rovided the cultivar of perennial ryegrass is adequately adapted for seed p roduction. The seeding rate for the perennial ryegrass is not particularly critical and 150-300 viable seeds m(-2) should be adequate for diploid pere nnial ryegrass grown in rows with a grain companion crop.