Studies On Community Characteristics And Propagation Technique Of The Endangered Plant Parakmeria Omeiensis Cheng

Parakmeria omeiensis Cheng is the rare plant endemic to Emei mountain in China, which was listed as the first level protected paints of China.The total number of the Parakmeria omeiensis Cheng in wild is only more than 20.This article studied the community characteristics,tissue culture,grafting,PPO activity and total phenols content. The main results were as follows:1.The community characteristics of Parakmeria omeiensis Cheng.There were some scattered Parakmeria omeiensis Cheng in evergreen broad-leaved forest of Biandanyan in Emei Mountain.The community contained 50 plant species,belonging to 37 families and 48 genera,among them the dicotyledon had comparative advantage, accounting for 80%of the total community.Magnoliaceae,Fagaceae,Lauraceae and Rosaceae accounted for 10.8%of the total families in community,which contained more than 3 genera be regarded as the superiority.The distributions of the plants in this community were mostly in the tropic and subtropic area,which could be divided into 9 types,the ratio of the plants which was to be tropic was higher than temperate zone,and the universal tropical plant was dominated.In this community,the phanerophytes accounted for 74%,mesophanerophyta and nanophanerophyta accounted for 64%, chamaephytes,hemicryptophytes,geophytes and therophytes accounted for 4%,6%,8% and 8%.The coverage of the arbor layer was 70%,Theaceae,Podocarpaceae,Fagaceae and Magnoliaceae was dominated with high importance value,then the Aceraceae and Lauraceae.Parakmeria omeiensis Cheng were scattered in this community,the average height was 20m,the height of clearance was about 13.8m,the diameter reached 31cm and the average crown width was about 6m.The number of the Podocarpus neriifolius D.don, Neolitsea wushanica(Chun)Merr and Taxus chinenwsis var.mairei Cheng et L.K was ralativly much more in regeneration layer,and the Neolitsea wushanica(Chun)Merr was dominated,but the seedling of Parakmeria omeiensis Cheng was not found in this layer. The average coverage of the shrub layer was 72%,Y.confusa(McClure)Z.P.Wang et G.H.Ye was dominated,then the Myrisne semiserrata and Smilax bockii Warb.The plant species in herb layer was single,the coverage was 5%～30%,the Carex leucochlora Gge.was dominated.The biodiversity of the arbor layer was the highest,Simpson index of which was 0.8610, Shannon-Weiner index was 2.3062,the evenness was the highest,0.8508,the ecological dominance was the lowest,0.1390,then the regeneration layer,0.1823,the ecological dominance of the shrub layer was the highest,0.8521,the evenness was the lowest,0.1578.2.The tissue culture of Parakmeria omeiensis Cheng.The period from April to May was the optimal time for explants collection in cause of the pollution rate nearly 20%, Continuously sterilize twice(7+8) min was the suitable sterilizing condition for stem segment,the pollution rate was the lowest and the axillary buds induction was 74.3%.Medium supplemented with 10mg/L VC and 1g/L PVP could control browning efficiently,and the former was better,the browning rate was about 1/2 of the control,the induction of apical buds was 77.8%.The stems of Parakmeria omeiensis Cheng were taken as explants,the optional culture medium for the initiation was B5+6-BA1.5 mg/L+IBA0.1 mg/L,the startup rate was 92.9%.The optional culture medium for the elongation growth was MS+6-BA1.0+IBA0.1+NAA0.1或B5+6-BA1.5 mg/L+IBA0.1 mg/L.The optional culture medium for the induction of apical buds was MS+BA 0.5 mg/L +IBA 0.05 mg/L. B5+6-BA1.5 mg/L+NAA0.5mg/L was the optimal culture medium for callus induction of the stem segment of Parakmeria omeiensis Cheng,the explants were palced in darkness. April was the optimal time for explants collection to induct callus.MS(B5) +6-BA 0.2mg/L+ZT 0.2mg/L+NAA0.1mg/L was the optimal culture medium for bud multiplication.3.The grafting of Parakmeria omeiensis Cheng.The comparison of survival among different rootstocks and in different season,Magnolia liliflora Desr(Henan)＞Magnolia denudate＞Magnolia liliflora Desr(Jiangyou),Spring＞Autumn.4.The measuremen of the PPO activity and total phenols content of Parakmeria omeiensis Cheng.Studied on the best test condition and property of the PPO activity with fresh stem segment of Parakmeria omeiensis Cheng,provided the reliable testing method on browning mechanism in tissue culture for further exploring.The results showed that the best test condition on PPO activity of Parakmeria omeiensis Cheng was PH 7.0, 25℃,the temperature be too high or too below would inhibit the PPO activity,the optimal concentration of o-dihydroxybenzene was 0.14mol/L,among VC,Citric Acid and Na₂SO₄, VC was the best to control browning.PPO activity and total phenols content of Parakmeria omeiensis Cheng had close relationship with phenophase,PPO activity in growing season was higher than dormancy season,the total phenols content in growing season and dormancy season was higher than stooling stage.Studied on the dynamic change of PPO activity and total phenols content of stem segment explants in initial cultivation,the results showed that,in inoculation two weeks,PPO activity was rising trend,then decreased two weeks later,the dynamic change of total phenols content was rising,decreasing,and then rising.