Laura Marx and Oscar H. Will III
Kenyon Biology Department
Allelopathic plants release chemicals from their roots and/or leaves that inhibit the growth and germination of other plants around them. Sorghum (Sorghum bicolor) and sudangrass (Sorghum sudanense) are two annual grasses that are known to be allelopathic. These plots at the BFEC are part of a project investigating the effects of sorghum and sudangrass on common Ohio weed species. In May 1998, each plot was planted with corn, sorghum, or sudangrass, or was left open as a control. Our hope is that in a few years, the plots that contain sorghum and sudangrass will have considerably fewer weeds than the corn and control plots. Six of the plots were planted with irradiated sorghum or sudangrass. These grasses, when exposed to low levels of gamma irradiation as seeds, produce more allelopathic chemicals than normal. Lab studies are underway to test both irradiated and normal plants to see if irradiated sorghum and sudangrass are more toxic to some of the weed species growing in these plots (such as the foxtail that has taken over some plots, broadleaf dock, and Canada thistle).
One of several study plots containing sorghum
Sorghum and sudangrass can potentially be used as natural herbicides. Previous experiments done using green mulches (chopping up the grasses and allowing them to decay on top of the soil they were grown in) of sorghum have found that sorghum can kill off up to 75% of the weeds that surface in a field at the beginning of a growing season. To find out more about sorghum and sudangrass allelopathy, or if you're interested in working on this project next year, please email marxL@kenyon.edu.