The effect of annual ryegrass (Lolium rigidum) interference on the growth of four common Australian crop species

摘要

Lolium rigidum (annual ryegrass) is a ubiquitous weed of southern Australia infesting the majority of winter crops. This paper considers the role of allelopathy in the interactions between L. rigidum and the associated crop species to improve the understanding of why L. rigidum is such a successful weed. Four crop species, i.e. lupin, barley, wheat and canola, were exposed to root exudates of L. rigidum to determine the extent of variation in growth responses. At high L. rigidum densities, root lengths of all crop species were inhibited. Increasing the duration of L. rigidum grovih in the agar medium before introduction of the crop species further reduced crop growth. However, growth responses differed between crop species. Canola was the most affected by L. rigidum interference (67% root inhibition) followed in declining order by wheat (56% root inhibition), barley (37%) root inhibition) and lupin (31%) root inhibition). Activated carbon and removal of L. rigidum plants prior to crop sowing wereused to verify the presence of putative inhibitory chemicals.