Plant growth inhibition by Imperata

What is it about?

Imperata cylindrica is a perennial rhizomatous grass widely distributed in tropical, subtropical and temperate regions over the world. The grass is strongly invasive and is suggested to have allelopathic potential. The extracts of cogongrass rhizomes inhibited the root and shoot growth of barnyard grass, ryegrass, timothy, cress, lettuce and alfalfa. After bioassay-guided separations of the extracts, four growth inhibitory substances, 5-methoxyflavone, 5,20-dimethoxyflavone, methyl caffeate and abscisic acid, were isolated. 5-Methoxyflavone, 5,20-dimethoxyflavone and methyl caffeate significantly inhibited the root and shoot growth of cress at concentrations of ≥0.03–0.3 m mol L−1 and their concentrations required for 50% growth inhibition were 0.079–0.24, 0.23–1.1 and 0.59–0.88 m mol L−1, respectively. The other isolated substance, abscisic acid, has been reported to have strong growth inhibitory activity. Its concentrations required for 50% growth inhibition on cress were 0.31–0.61 μ mol L−1.

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Why is it important?

The present study suggests that cogongrass rhizomes might have allelopathic potential and that those four substances might contribute to that potential.