Comparison of the yield, nitrogen and phosphorus content, and rust infection (Puccinia coronata) of irrigated ryegrass swards in south-eastern Queensland

Abstract

Thirteen ryegrass (Lolium spp.) cultivars and three mixtures of cultivars were evaluated in a series of experiments over four years at two sites in south-eastern Queensland. Stands were sown at 30 kg/ha of viable seed and fertilized with 50 kgN/ha at sowing and after each defoliation. After an establishment period of 6-8 weeks, stands were defoliated every 21 d. Lolium multiflorum cv. Midmar was the highest yielding or equally highest yielding cultivar in three of the four years. Its forage production was better distributed over the full growing season (April- December) and its foliage was less affected by leaf rust (Puccinia coronata Corda) than any other single cultivar. L. rigidum cv. Wimmera was the best cultivar for early season production (before June) and the perennial cultivars (L. perenne cv. Kangaroo Valley and [L. multiflorum x L. perenne] x L. perenne cv. Grasslands Ariki) and cv. Midmar were superior late in the season (September-December). There was little difference in the performance of the other annual (L. multiflorum) cultivars before September. Grasslands Tama gave poorest late season yields. The only mixture that yielded more than its individual components was the Grasslands Tama/Grasslands Ariki combination. Its yield and the distribution of that yield were equivalent to cv. Midmar. Midmar had slightly lower nitrogen levels in the foliage than the other cultivars, but differences were not substantial. The relative ranking of ryegrass cultivars for resistance to rust was Midmar > Kangaroo Valley and Grasslands Ariki > Richmond and Tetila > Grasslands Manawa and Grasslands Paroa > Grasslands Tama, Wimmera, Tetrone and Tetralite.