Oat Caryopsis Size and Genotype Effects on Wild Oat–Oat Competition

Abstract

The inherent similarity between wild oat (Avena fatua L.) and oat (A. sativa L.) precludes selective herbicide control of wild oat. Previous studies have reported improved crop yield and competitiveness with the use of large seed. Therefore, a greenhouse experiment was conducted in 2002 and 2003 to examine the effect of caryopsis (dehulled kernel) size and genotype on wild oat–oat competition. Seeds of three oat cultivars (AC Assiniboia, CDC Boyer, CDC Orrin) were classified into three size classes based on caryopsis size (large, ≈35 mg; medium, ≈25 mg; and small, ≈15 mg). Whole oat seeds of each genotype and caryopsis size treatment were grown either in monoculture or in mixture with wild oat (250 plants m−2). Neither genotype nor caryopsis size significantly influenced (P < 0.05) oat emergence. Nonetheless, oat plants established from large caryopses produced 17% more biomass (P < 0.001) and 15% more panicles m−2 (P < 0.001) than plants established from small caryopses. Wild oat produced 23% less biomass (P = 0.004) and fewer panicles m−2 when grown with oat plants established from large caryopses. Genotype only influenced oat panicle production (P = 0.05) and did not affect oat (P = 0.09) or wild oat (P = 0.34) aboveground shoot biomass production. These results suggest that oat plants derived from large‐seeded caryopses may be better able to tolerate wild oat interference. However, further investigation is needed to examine the response of oat–wild oat competition to oat caryopsis size and genotype under field conditions.