Wild radish (Raphanus raphanistrum L.) development and seed production in response to time of emergence, crop-topping and sowing rate of wheat

M.J. WalshA and D.M. MinkeyB

A Western Australian Herbicide Resistance Initiative, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.

B Centre for Cropping Systems, Lot 12, York Road, Northam, Western Australia 6401, Australia.


To determine if increasing crop sowing rates suppresses the competition effects of wild radish, field trials were conducted in 2000 at Avondale and Goomalling, Western Australia. Higher wheat sowing rates, whilst increasing wheat biomass and grain yield, were found to have a limited impact on the biomass and plant density of wild radish. However, wild radish seed production was reduced by 35 and 33% at Avondale and Goomalling respectively when the conventional wheat sowing rate of 60 kg ha-1 was tripled to 180 kg ha-1. Similar reductions in wild radish seed production were achieved by removing the early wild radish cohort at Goomalling. When two wild radish cohorts were removed at Avondale there was a 77% reduction in seed production. These studies determined that the biggest impact on wild radish growth and development was due to early cohort removal whilst higher wheat sowing rates produced substantial reductions in wild radish seed production only.

Keywords: Sowing rates, crop competition, weed suppression.


Plant Protection Quarterly (2006) 21 (1) 25-29.