Studies On Elite Clone Selection Of Tripterygium Wilfordii Hook.f.

Based on the wild habitats and plantations of Tripterygium wilfordii(TW) in Taining County(TNC),the studies focused on both autoecology research and clone selection so as to provide either the basic scientific data for TW's domestication and the theoretic knowledge for the improvement of canes and medical plants.The overall survey of TW resources was carried out according to the data of TNC agriculture subdivision and soil survey and the phenological observation was implemented in the 2 spots which located on Luxia and Jiangkeng of TNC.The natural generated population of TW in Luxia was applied to explore the variation within the species,while the plantation in Yuxi for the study of TW autoecology and elite individual selection.In Fujina Forestry Academy,the clonalization of the selected plants was achieved using root cuttings,furtherly the growth and photosynthetic physiologic characters of clonal plantlets were tested using CI-301 CO₂ Analyzer,which made in USA.The content of endogenous growth regulators and triptolide in TW seedlings were measured by ELISA and high efficiency liquidphase chromatography(HELC) respectively.Also the clonal propagation by cuttings was experimented using date,cutting, medium and growth regulators as the elements.The following was the achievements.The natural prospects of TW main distribution region were as the following:â‘ Climate:The annual accumulation of temperature higher than 10℃,rainfall and relative humidity is 5000～5500℃,1700～1800 mm and 80～86%respectively;â‘¡Altitude:The high hilly area with altitude 300 to 500m is the adequate distribution zone for TW,and the valley at altitude 200 to 300m and mountains with 500 to 800m as the general zone.The mountainous area with altitude 800 to 1700m is TW's boundary zone.â‘¢Topography:In the elevation between 300 and 500m, TW grows better in light and southwide lope than in tiff and northwide. On the same slope,it grows best in the foot.Regarding on the micro-topography,it grows better in the concave than in the convex and platform.â‘£Soil:The soil category of TW natural distribution allocated in the red soil 90%,yellow soil 5%and purple soil 5%.The average PH is about 6,varying from 5 to 6.5 and suggests TW prefers light acid soil.⑤Vegetation:In the TW community there are 135 plant species belong to 111 genus of 60 families,of which 11 fern species of 11 genera in 8 families,4 gymnosperm species of 4 genera in 4 failies,120 angiospermous species of 96 genera in 48 families(98 dicotyledonous species of 77 genera in 41 families and 22 amphibrya species of 19 genera in 7 families).In a year-round,TW has 2 shoot growing periods which is in the spring and autumn respectively.The spring one lasts about 120d,of which growing peak longests 100d and the growth in the foot part of slope is more than that in the up.The autumn one is about 70d,of which growing peak lasts 50d.Generally the growth of spring shoot is bigger than that of autumn one.TW develops flower buds on middle April,starts flowering on early or middle May,fruits ripen on middle or late September.TW bears flower and fruit once a year and the fruit crop presents the rythum of plenty and poor alternativelyGreat inner-species variance were observed for TW and the variance index of crown width(CW),branch number(BN),ground diameter(GD) and main cane length(MCL) was 55.73%,59.52%,38.27%and 53.2% respectively.The growth traits were closely correlated with each other and very obvious correlation happened between CW and GD,CW and MCL,GD and MCL,while visible between CW and BN.The distribution of TW root system in different slope position decreases along the increment of soil depth.The slope position effect is obviously presented in TW root growth,which more roots in the bottom and mille than that in the up.The water content in TW root increases gradually from the bottom to the top of slope with an average at 43.88% and the distribution of roots at different diameter grades was simillar in different position on slope,i.e the roots with big diameter is more than that mediate and small and the big ones accounts for 62.18%of the total. The biomass of TW root,stem and leaf accounts for 52.75%,37.67%and 9.58%respectively.The correlation between biomass and GD,average cane diameter and BN is visible or very visible and a model for estimation of biomass was successfully formatted using BN,GD,ACD and ACL as the self elements by best formula.The reasonable select ratio for plus tree selection in TW plantation is 16.For BN as selection objective the reasonable select ratio is 1.5 times of the standard.And that for GD,ACL,and ACD is 1.45,1.45 and 1.85 respectively.In the end 23 elite trees were selected by exponant from 36 candidate trees at select ratio of 1.05%,of which the growth is 1.47 to 1.8 times of the stand average.The average survival rate of the cuttings from the 23 plus trees was 94.4%and no disease or insect damage was found.The TW cuttings grow rhythm is typical as "rapid- slow-speed -stop".The variance of BN,GD, ACL at 1.5-years-old plantlets is visible and the generalized heritibility of BN,GD is 0.3612,0.4664.The growth of the 23 clones is better than the checked and the 23 clones can be classified into 4 groups by hierachical cluster analysis,ie.the trong,stretch,mdiate and normal.A general correlation was found among the 3 growth traits in the seedling stage,of which GD is the central trait correlated with the others.Using GD and BN as the select criteria,10 elite clones were selected with rapid growth at nursery stage and their average growth gain of BN and GD was 10.17%and 22.75%respectively,compared to the average of the 23 clones.The daily variance of net photosynthetic rate in TW plantlets tends to be a two-peak curve with a pause at noon.Also the leaves in the down part were found to present the daily variance trend of net photosynthesis more precisely than that of both the up and middle and the results suggested TW is a mediate shade-resistant plant as its general or poor adaptability to sunlight with a photo compensation point at 17u mol.m^-2.s^-1 and saturation at 600u mol.m^-2.s^-1.The net photosynthesis rate was found correlated positively with air temperature,leaf temperature,efficient radiation of photosynthesis and vapouring rate,negatively with air relative humidity,leaf water content,concentration of CO₂ inner cell or between cell and invisibly with air CO₂ concentration and.The growth of TW main cane was influenced obviously by net photosynthesis rate and vaporescence rate but non-obviously by BN,GD growth and plant photosynthesis.Finally the photosynthesis variance among the TW clones was significant,of which clone 17,13,16,10,11,4 and 6 had higher net photosynthesis rate.Significant variance of endogenous hormone content was found among the TW clones regarding on IAA,GA,ABA and ZR and obvious correlation was found among the 4 endogenous hormones,of which very positive among IAA,GA and ZR.It suggested the content of 3 hormones is closely correlated with each other and the variance trend similar among different clones.By the way the ABA content is independent with the others.The hormones should play influential effect on the growth and development of TW plantlets by interaction or.The content of triptolide in the root xylem of TW clone plantlets was 1.29 times as that in the phloem and its variance between the 2 parts was visible,which was 2.09 and 3.1 times as those of the checked respectively. The triptolide contents of root xylem and phloem were correlated with each other very obviously,but the correlation was invisible between the triptolide contents of root and growth traits,photosynthesis factors and content of endogenous hormones.Fatherly 2 elite clones with high triptolide content were selected by index screening,of which one with double advantages,i.e.rapid growth and high triptolide content.Although seasoning was not very restricted for TW cutting propagation,the high temperature in the summer did affect the cutting survival rate.As a result,the best season for cutting is on February to March or in the 'little spring' of September.No root promotor needed on February to March.Otherwise ABT2 or ABT3 was suitable for root cutting and ABT1 for branch.The plantlets from root cuttings seemed to grow more branches,better roots and growth than that from stems.Of the branch cuttings the highest survival rate was achieved using cuttings form meddle section,which followed by the bottom and the poorest from the upper.The most suitable section length for root cutting was 6 cm to 8 cm and that of branch 12 cm to 15 cm.More substrates could be used for root cutting than that for branch cutting and the sandy soil was the best economically.Based on the studies concerned with development environment survey,phonological observation,inner-species variance,root distribution, plant biomass allocation pattern and biomass model,the research covered an area including autoecology,plus tree selection,growth characters, photosynthesis traits and contents of endogenous hormone and triptolide at nursery stage.As a result,10 elite clones with rapid growth at nursery stage,2 clones with high content of triptolide and 1 clone with both rapid growth and high triptolide content were selected and the TW cutting propagation procedures and breeding policy were successfully developed. The results could provide the material base and technical assurance for TW breeding,improved varity deployment and industry development and filled the gap of research concerned in the domestic and abroad.