Are two cultivars better than one? Performance of leafed and semi-leafless pea mixtures under weedy conditions

Non-Peer ReviewedThere is a need for improved tools to minimize yield losses due to weeds for organic field pea production. Cultivar mixtures may improve the ability of organic pulse crops to suppress weeds and maintain yields in the presence of weeds. While semi-leafless peas are known for their lodging resistance and high yield potential in the absence of weeds, leafed (wild-type) peas may provide better weed suppression and yield stability in the presence of weeds. A replicated field experiment was conducted on organic land over five site-years to test the hypothesis that mixtures of leafed and semi-leafless field pea cultivars would improve weed suppression and yields relative to monocultures of the same cultivars. The experiment tested factorial combinations of five ratios of semi-leafless (cv. CDC Patrick or CDC Dakota), and leafed pea (cv. CDC Sonata) (0:100, 25:75, 50:50, 75:25, and 100:0, respectively), and two target seeding rates (88 and 132 plants m-2). Plots were monitored for crop and weed emergence, biomass, and yields. Mixtures differed from their component monocultures in both weed control and yields. Levels of weed control in mixtures were intermediate to the component cultivars, and no weed control benefits were seen. While CDC Patrick mixtures did not out-yield CDC Patrick monocultures, mixtures of 75% CDC Dakota and 25% CDC Sonata out-yielded both respective monocultures by 12-196%. Results indicate that mixtures of leafed and semi-leafless cultivars may be used to improve organic pea yields in the presence of weeds. However, specific combinations of cultivars and mixing ratios should be evaluated on a case-by-case basis