Three wild oats phenotypes were grown in wheat stands sown at different dates in greenhouse and field trials. Wild oats growth and seed output, and their effects on wheat biomass were not different among phenotypes when wild oats emerged 2 wk after the wheat. In experiments in which wild oats were planted in germinated wheat, one phenotype was shorter, weighed less, and produced fewer seed than the other phenotypes. Another phenotype reduced wheat biomass more than the other phenotypes. Vernalization increased vegetative growth and reduced spikelet production of one phenotype, but had no effect on its competitiveness with wheat.
