Abstract
A factorial experiment was conducted under outdoor conditions from September 1999 to June 2001 to assess the effects of winter wheat cropping systems on the demography of wild oat (Avena fatua L.), a problematic weed in winter cereals. The simulated cropping system, and in particular tillage, significantly affected the number of wild oat plants per pot. The number of wild oat plants increased under a summer till-autumn till system, whereas plant number decreased under a summer no-till system. When no-till in summer was followed with no-till in autumn, wild oat disappeared in certain plots by June 2001. The decrease in the number of wild oat plants under a summer and autumn no-till system was likely to be related to the advanced emergence induced by no-till leading to relatively reduced survival. Application of calcium cyanamide prior to seeding of wheat increased wheat ear number and wild oat panicle number. Under a summer no-till system, the number of wild oat plants increased with calcium cyanamide application, indicating stimulation of emergence. These results suggest that tillage regime can have a strong effect on wild oat demography in winter wheat fields, indicating that integrated control of wild oat should include no tillage throughout summer and autumn.
