Allelopathy of Eucalyptus urophylla on Eight Native Tree Species

Aqueous leaf leachate and leaf volatile of Eucalyptus urophylla were used to test their effects on seed germination and seedling growth of eight native tree species,including Schefflera octophylla,Acmena acuminatissima,Cleistocalyx operculatus,Ilex triflora,Schima superba,Cyclobalanopsis myrsinaefolia,Hovenia dulcis,Michelia maclurei.The results showed that aqueous leaf leachate had no suppression on the seed germination of all receptors.Aqueous leaf leachate had inhibition on the seedling growth of Schefflera octophylla,Acmena acuminatissima and Ilex triflora,while it had a promotion on that of Cyclobalanopsis myrsinaefolia and Hovenia dulcis at higher concentration.Leaf volatile had inhibitory effect on the seed germination of Acmena acuminatissima and Schima superba at higher concentration of 350 g leaf weight per desiccator,and Schima superba at 250 g leaf weight.However,it had no suppression on them under 150 g leaf weight treatment.On the other hand,leaf volatile had a significant suppressive effect on the seedling growth of Acmena acuminatissima,Ilex triflora,Schima superba,Hovenia dulcis and Michelia maclurei at all concentrations.Leaf volatile also effectively decreased the seedling growths of Schefflera octophylla and Cleistocalyx operculatus at 250 g and 350 g leaf weight.It did not inhibit the growth of Cyclobalanopsis myrsinaefolia utill at the concentration of 350 g leaf weight.With these results,we can conclude that Eucalyptus urophylla has allelopathy and the allelochemical effects of the donor varies with the dose.It seems that allelopathy of leaf volatile is more intense than that of aqueous leaf leachate.Nevertheless,seedling growth is more easily suppressed than seed germination.