Studies on desmodium species for the allelochemicals involved in striga suppression

Abstract

The fodder legumes Desmodium uncinatum and D. intortum suppress the growth of Striga hermonthica (witch-weed) via an allelopathic mechanism that involves Striga germination stimulants and post-germination growth inhibitors. In this study, the root extracts (dichloromethane, acetone and methanol) from the two Desmodium species were investigated for Striga germination stimulation and post-germination radicle growth inhibition activities. The less polar extract (dichloromethane) showed Striga germination stimulation activity of over 40% at 10 ppm, but did not show any post-germination radicle growth inhibition at the same concentration. On the other hand, the polar extracts (acetone and methanol) were found to exhibit post-germination radicle growth inhibition activities of over 45% at 10 ppm.