Impact of seeding rate on annual ryegrass performance

Annual ryegrass (Lolium multiflorum Lam.) is a primary forage resource for livestock producers throughout the south-eastern USA during the winter-growing season. It is important for livestock producers to begin grazing annual ryegrass as early as possible and any management practices maximizing early season production could be beneficial. To assess the impact of seeding rate on subsequent yield, yield distribution, quality, seedling density, and end-of-season plant and tiller density, a 2-year study was initiated at four locations in Louisiana. Three annual ryegrass cultivars, varying in seed size, were established at four seeding rates based on pure live seed (PLS) rates of 400, 800, 1200 and 1600 PLS m(-2). There was no advantage in total yield from increasing seeding rates beyond 800 PLS m(-2). However, first-harvest yields increased from 360 to 930 kg dry matter (DM) ha(-1) as seeding rate increased from 400 to 1600 PLS m(-2). Crude protein and neutral-detergent fibre concentrations, and in vitro DM digestibility, were not affected by seeding rate. Seedling density and end-of-season plant numbers increased as seeding rate increased. However, stems per plant decreased as seeding rate increased, indicating compensatory tillering for the reduced plant numbers observed at the lower seeding rates. These results indicate first-harvest yield can be increased by planting at higher seeding rates but total yields are not increased.