Ecology of annual ryegrass
Gurjeet S. Gill, Co-operative Research Centre for Weed Management Systems, Department of Agronomy and Farming Systems, The University of Adelaide, Roseworthy Campus, Roseworthy, South Australia 5371, Australia.
Annual ryegrass (Lolium rigidum Gaudin) is a major weed of cropping in southern Australia. It is a prolific seed producer and figures as high as 45 000 seeds m-2 have been reported. L. rigidum seeds have a short period (about two months) of innate dormancy. A proportion of the seed bank can have dark-dormancy which has been suggested as a factor contributing to short term persistence of buried seeds of L. rigidum in crop-pasture rotations. Seed by environment interactions allow a large proportion of the seed bank to survive until well after crops have been sown. Depending on its density and time of emergence, L. rigidum can be highly competitive with the crop and the competition can start as early as the two-leaf stage of the crop.
Plant Protection Quarterly (1996) 11 (Supplement 1) 195-198.