Inhibitory Effects of Paeonia suffruticosa Leaves and the Extracts by Different Solvents on Seedling Growth of Lactuca sativa and Some Other Plants

In order to further understand the allelopathic activities of Paeonia suffruticosa leaves,indoor test was carried out via agar mixed powder(PPA) method to detect effects of Paeonia suffruticosa leaf powder under different concentrations on seedling growth of 7 receptor plants including Lactuca sativa L.var.ramosa Hort.,Triticum aestivum L.,Cucumis sativus L.,Echinochloa crusgalli L.,Lagopsis supine(Steph.) Ik.-Gal.ex Knorr.,Descuminia Sophia L.and Lepidium apetalum Willd.Results showed that influence of Paeonia suffruticosa leaf powder at low concentration on seedling growth of each receptor plant was quite different,but relatively high inhibition effects could be were observed at high concentration,and particularly inhibition effects on radicles(or seminal roots) were significantly higher than that of hypocotyls or coleoptiles.The EC50 an effective dose for half lethal value corresponding to radicles(or seminal roots),and hypocotyls(or coleoptiles) respectively for each receptor plant,calculated as follows.L.sativa 0.93-5.25 g/L,T.aestivum 1.20-4.65 g/L,C.sativus 3.58-10.0 g/L,E.crusgalli 0.64-3.36 g/L,L.supine 1.09-5.27 g/L,D.Sophia 1.02-9.65 g/L,L.apetalum 0.79-6.84 g/L.Among them,E.crusgalli and C.sativus presented the highest and the lowest susceptibility to peony leaves respectively.Meanwhile,effect of peony leaves extract derived from different solvent(ethanol,methanol and distilled water) on seedling growth of L.sativa was tested respectively with a result that ethanol extract presented the highest inhibition activity on receptor plant seedling growth,and the optimum ethanol concentration for extraction was 80%(V/V).