Potential ecological implications of extensive cereal rye cover cropping in the United States

Cereal rye (Secale cereale L.) is the most widely grown small grain cover crops in the United States. The rapid and intensive expansion of cereal rye as a cover crop for soil conservation and weed suppression may raise the concern of its invasiveness with ecological implications in a few years. Cereal rye has greater chances of developing weediness as compared to other small grain cover crops such as winter wheat and barley. This is partially due to multiple cycles of unintentional or ill-defined human selection and stringent domestication efforts during the process of its evolution, which has reduced the genetic diversity in cereal rye but helped retain traces of weedy traits. Furthermore, unrestricted gene flow due to natural hybridization and incomplete speciation because of weak domestication bottleneck have led to incomplete lineage sorting among the Secale species. This has increased the risks of introgression of weedy characters like delayed flowering and shattering seedhead from wild ancestors and feral rye into cereal rye. The introgression and naturalization of weedy alleles may enable cereal rye to overcome all the barriers of plant invasion, making it an aggressive competitor for resources like nutrient and water as compared to most field crops. Therefore, while the entire northern American agriculture is undergoing extensive adoption of cereal rye cover cropping, it is critically important to assess its invasive potential and implement effective management strategies for its containment, ensuring sustainable agricultural practices and preventing ecological disruptions.