Studies On The Allelopathy Of Ent-kaurane Terpenoids From Isodon Excisoides(Sunex C.H.Hu)

The fought extracts and three compounds of ent-kaurane Terpenoids from Isodon excisoides[(Sunex C.H.Hu)C.Y.Wu et H.W.Li]is selected to study its effect on seed germination,seedling growth,leaves photosynthetic pigments content,membrane permeability,MDA content of different test plant(Wheat,Radish,Chinese gabbage, Barnyard grass,Lecture)and callus cell of Pinellia ternate Breit.Its rule and effect on seed germination,seedling growth of test plant in allelopathy is discussed and the type of allelochemicals in Isodon excisoides was selected and compared in the paper.The main results are as follows.1.The different restrainability of the rought extracts and three compounds of ent-kaurane Terpenoids on seed germination of different test plants is found in test.But the promotion of growth on seed germination is not found.The seed germination and restrainability on seedling growth and development of test plants and the allelopathic character of"low-promotion and high-restrainability" is found in the experiment.The feeble promotion on seedling growth was exhibited under low treating concentration.But promotion of seed germination was not discovered.Its restrainability on seedling growth increases with increasing of its treating concentration and there is evident linear relation depend upon concentration exhibited.The RWC of seedling and wastage of cultural solution minish with increasing of its treating concentration under three pure compounds. Otherwise,The form of leaves,root and root hair of test plants is also affected and damnified in some extent.Its effect and damnifation on form of seedling and root top increase with increasing of treating concentration.2.The sensitivity of different test plant and different part of same test plant on the rought extracts and three compounds is different.The restrainability exihibits selectivity on species.And the sensitivity of different test plant on fought extracts is lecture＞Barnyard grass＞Wheat in turn and the sensitivity of different test plant on three pure compounds is lecture＞Barnyard grass＞Chinese gabbage and Radish in turn.The restrainability of root elongation is notablest in all tested index under three compounds.The restrainabilc intensity of fought extracts and three compounds on seedling growth and development of test plants is DH-5＞C-21＞DB-3in turn.EC₅₀of fought extracts is between 425.95 and 704.15μg/ml and EC₅₀of three compounds is between 6.46 and 69.35μM.There is positive relativity between EC₅₀of restrainability of rought extracts and three compounds on test plants and its weight per hundred seeds.3.The depressed extent on photosynthetic pigments content of leaves of different test plants increase with increasing of its treating concentration under the rought extracts and three compounds and there is evident linear relation exhibited depending upon concentration. The extent of depression on different photosynthetic pigments is different.The chlorphyl(a) is fall in greatest extent.These result indicate that the rought extracts and three compounds could weaken photosynthesis of test plants by depressing photosynthetic pigments content and this result exhibited on seedling growth finally.4.The membrane permeability and MDA content of leaves of test plants increased with increasing of its treating concentration under the rought extracts and three compounds.The result indicates that cell membrane of test plants appear to lipid peroxidation and different-extent darnnification.5.The Pinellia ternate Breit.callus cell growth also appears the allelopathic character of "low-promotion and high-restrainability" under treatment of rought extracts in 15～150μg/ml.The Pinellia ternate Breit.callus cell has not evident growth under the rought extracts.The report on allelopathic mechabism is refered.First,the rought extracts and three compounds could weaken photosynthesis of test plants by depressing photosynthetic pigments content and increase lipid peroxidation and damnification on cell membrane by increase membrane permeability and MDA content of seedling.Second,the absording function root is depressed by damnification of root and seedling.The two results exhibited effect on seedling growth finally.Isodon excisoides[(Sunex C.H.Hu)C.Y.Wu et H.W.Li] belong to delifoliate plant,this conld speculate that the rought extracts and three compounds could put in living entironment by delifoliation and erode of rainwater,and bring effect on growth of plant.The rule incarnates natural regulation of community in natural selection,ts further mechanism of the allelophics will is study further in future.