Allelopathic effects of ethanol extract of three medicinal plants from rubiaceae family on seed germination and seedling growth of Raphanus sativus L.

The allelopathic effects of ethanol extract of Paederia scandens(Lour.) Merr., Hedyotis caudatifolia Merr. et Metcalf and Mussaenda pubescens L. on Raphanus sativus L. were compared by determining germination, chlorophyll content, free proline content of leaves and root activities of the acceptor. Results showed that different concentration of ethanol extract from donors had certain allelopathic effect on R. sativus, and the allelopathic effects enhanced with the increase of concentration. Ethanol extract from donors significantly reduced germination percentage, germination rate index.And H. caudatifolia in the inhibition of these two indexes was significantly higher than the other two donors. The three donors all significantly inhibited the seedling growth of radish, with the strongest inhibition of germ and radical growth caused by P. scandens and M. pubescens, respectively. P. scandens also caused more significant inhibition of root activity of R. sativus than M. pubescens, while H. caudatifolia remarkably improved it. Ethanol extract from donors significantly increased the free proline content of acceptor's leaves, and resulted in 69.47%-87.00% reduction of the chlorophyll content of acceptor, while chlorophyll A / chlorophyll B decreased as the increase of ethanol extract concentration.