Mitigating Reduced Yields of Corn Following a Winter Rye Cover Crop

Title:  Mitigating reduced yields of corn following a winter rye cover crop: what role does allelopathy play?

Location:  Iowa State Campus

Time Period:  2019 -2020

Research Team:  Alison Robertson

Project Description:  Environmental benefits associated with growing cover crops (CC) are well documented. In Iowa, winter rye is the most extensively used CC. In some years and fields, however, corn yield decreases have been reported following winter rye CCs, consequently, many corn producers are hesitant to try CCs. Potential causes of this yield decline include allelopathy and planting issues. We demonstrated winter rye serves as a green bridge for soil-borne pathogens of corn and seedling disease may also play a role in yield decline. However, seedling disease cannot solely be blamed. We hypothesize that allelopathy may also play a role in yield decreases of corn in the winter rye-corn production system. Winter rye produces numerous allelopathic compounds that may affect corn growth and development, and the soil microbial community, including plant pathogens. The persistence, availability and activity of allelochemicals is influenced by a range of biotic and abiotic factors. We are curious if allelopathy could explain why corn yield decreases occur in some fields but not others. The central hypothesis of our proposed project is when corn is planted into rye residue, corn growth is stunted and seedling roots more rotted because rye allelochemicals enhance seedling disease caused by Pythium spp. This proof of concept study will provide (i) data regarding the interaction of allelopathic compounds and corn seedling pathogens in a lab-based assay. If an interaction is detected, the data will inform further research in this area.

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Funders:  Iowa Nutrient Research Center