Effect of seeding rate and ryegrass type on sward tiller density and productivity under simulated grazing

摘要

The objective of this study was to establish the effect of ryegrass type and seeding rate on sward density and total dry matter (DM) yield under simulated grazing management. Swards with higher tiller densities of ryegrass tend to have greater DM production. Four perennial ryegrass varieties, AberChoice (diploid -D), AberGain (tetraploid - T), Glenveagh (D), Twymax (T) and two hybrid ryegrass varieties, Amalgam (T) and Ligunda (D) were sown in autumn 2013, each at 7.4, 14.8, 22.2,29.6 and 37 kg ha~(-1). The swards were simultaneously grazed for the remainder of 2013 (establishment year) with 2014 and 2015 taken as the harvest years. Under simulated grazing management plots were defoliated on nine occasions each year. Plots received nitrogen applications following each harvest totalling 250 kg N ha~(-1) yr . There was no seeding rate by variety interaction found on DM yield or tiller density. Seeding rate was found to have no effect on total DM yield but a significant effect on tiller density (/><0.0001). Grass variety had a significant effect on both total DM yield and tiller density (P<0.0001): AberChoice (13.4; 6,015), AberGain (14.2; 3,776), Glenveagh (12.6; 5,511), Twymax (13.3; 4,000), Amalgam (13.3; 3,376) and Ligunda (14.8; 3,336) (t DM ha~(-1), tillers m'2 respectively). These data show that tiller density docs not limit variety yield potential within the first 2 full production years.