| Codonopsis pilosula is the root of C.pilosula(Franch.)Nannf.or C.pilosula Nannf.var.modesta(Nannf.)L.T.Shen or C.tangshen Oliv.It is widely used as a common Chinese herbal medicine compatibility with other herbs,as soup,tea and other food seasoning.Located in the arid and semi-arid regions of northwestern China,Gansu’s Longnan,Dingxi,and Longxi are the main planting areas of C.pilosula.Therefore,it is of great significance to explore the effects on the growth and component accumulation of C.pilosula under different soil moisture.In this paper,it revealed that the effects of three kinds of soil moisture on C.pilosula by measuring physiological characteristics,growth and development,active ingredients and accumulation of trace elements and heavy metals,which could provide theoretical basis for C.pilosula cultivation of high yield,stable yield,high quality.The main findings are as follows:1.The photosynthetic characteristics effects of C.pilosula under different soil moisture were as follow: The photosynthetic rate(A),transpiration rate(E),intercellular CO2 concentration(Ci),and stomatal conductance(Gs)of C.pilosula plants showed the trend of suitable moisture treatment> mild drought> severe drought treatment,but its change trend is slightly different.The photosynthetic rate showed a downward trend under mild and severe drought treatments;under suitable moisture treatment,it decreased firstly,and the latter its changes was not obvious.Under the three soil moisture treatment,transpiration rate(E)showed increased firstly and then decreased;the changes of intercellular CO2 concentration was W-type and showed a maximum at the 60 th day of treatment;The change of stomatal conductance(Gs)increased firstly and then decreased under the suitable moisture treatment,while it showed the tendency of fall-rise-fall under mild and severe drought.Compared with suitable moisture treatment,the photosynthetic rate(A)of C.pilosula continued to decrease within 100 days of drought stress.Combined with these changes of intercellular CO2 solubility(Ci),water vapor stomatal conductance(Gs)and chlorophyll content analysis,the cricial factor affecting the decrease of photosynthetic rate was stomatal factor in the first 80 days,after mainly non-stomatal factor.In addition,C.pilosula adapt to this continuous drought adversity through the continuous increase of carotenoid content,the continuous decrease of intercellular CO2 solubility and transpiration(E)after 60 days of drought treatment.2.The protective enzymes effects of C.pilosula under different soil moisture were as follow.Under the three soil moisture treatment,the activity of POD,CAT and soluble protein content were inverted V type;and the activities of SOD,POD,soluble protein and CAT activity reached maximum on the 80 th and 60 th days of treatment,respectively.Under the three soil moisture treatment,MDA content continued to increased,but soluble sugar content decreased continuously.In addition,under drought stress,the activities of SOD,CAT,POD,soluble protein and MDA in the leaves of C.pilosula showed the trend of severe irrigation> mild drought> suitable moisture treatment and the change trend of soluble sugar content was the opposite,showing the trend of suitable moisture > mild drought> severe drought.It showed that drought stress was not conducive to the growth of C.pilosula and the greater the degree of drought,the greater the poison.3.The growth and composition accumulation effects of C.pilosula under different soil moisture were as follow.Compared with suitable moisture treatment,under moderate and severe drought stress significantly inhibited the growth and biomass accumulation of C.pilosula seedlings;Codonopsis subject to resources constraints by regulating its shape(leaf length,Leaf width,root length,rattan length,etc.)and biomass allocation to adapt to long-term drought stress;Under drought stress,the growth of roots was relatively slower than the aerial part of C.pilosula.In addition,Under the three soil moisture treatment,the polysaccharides contents in aerial parts after 80 days treatment and roots after 60 days treatment of C.pilosula showed the trend of suitable water> mild drought> heavy drought.The content of syringin in aerial parts and roots of C.pilosula were higher than that of the other two soil moisture treatments;and the syringin content in aerial parts of C.pilosula increased in the entire 100 days after three soil moisture treatments.The syringin content change in the root of C.pilosula was inverted V type throughout the treatment process,and it reached maximum on the 80 th days of treatment.Under mild drought treatment,the lobetyolin contents in aerial parts after 80 days treatment and roots in entire 100 days treatment of C.pilosula were the largest.Under the three soil moisture treatment,the atractylenolide Ⅲ contents in aerial parts after 80 days treatment and roots after 60 days treatment of C.pilosula showed the trend of severe drought> mild drought> suitable moisture treatment.Therefore,it helped polysaccharide and lobetyolin accumulation of the aerial part and root of C.pilosula under suitable moisture treatment.Severe drought and mild drought stress promoted the accumulations of atractylenolide Ⅲ and syringin in the aerial parts and roots of Codonopsis.4.By analyzing the determination of six metal elements(Zn,Fe,Mn,Cu,Pb and Co)in the aerial parts,root and root region soil of C.pilosula plants,it was found that the correlation was not strong between element content and the soil p H under different soil water content;Experimental resulted show that the content of elements in root were increased by excreting certain compounds to promote the enrichment of elements in root region soil under mild drought treatment.Under the three soil moisture treatments,the content of Zn,Mn and Cu in the aerial part of C.pilosula seedlings was higher than that in the root;Therefore,The heavy metal content in root of Cu can be reduced by the biomass increase of the aerial part of C.pilosula seedlings,which is beneficial to the production of C.pilosula,because C.pilosula is root as a medicinal site.Therefore,it suggested that the content of heavy metal elements in root of C.pilosula can be regulated by adjusting soil moisture and aboveground biomass of C.pilosula in the mild heavy metal pollution area.5.Under the three soil moisture treatments,the content of syringin of C.pilosula root showed a strong positive correlation with the activity of SOD,POD and the length of rattan.The atractylenolide Ⅲ,lobetyolin content of C.pilosula root and growth indicators(length of the rattan and root,root diameter,aboveground and root dry weight,fresh total biomass),polysaccharide content were significantly strongly positive correlation;and photosynthetic rate(A),soluble Sugar,Cu showed a strong negative correlation.The results showed that the growth of C.pilosula seedling and polysaccharide content contributed to the accumulation of atractylenolide Ⅲ,lobetyolin content.Under suitable moisture treatment,the correlation between the metabolites of C.pilosula root was very strong,and the rattan length growth contributes to the accumulation of syringin content of C.pilosula root.6.The effects of waterlogging stress on the growth and physiological characteristics and polysaccharides of C.Pilosula were as follow.The results showed that,under the waterlogging stress,the same phenophase of C.pilosula lags behind that under normal irrigation conditions,and the lagging aggravated as the aggravation of waterlogging stress;under severe waterlogging and mild waterlogging stress,the SOD,POD,CAT activity of C.pilosula leaf kept rising within 14 to 56 days after treatment,and then fall;The soluble protein content decreased on the 42 thday after treatment;the soluble sμgar content constantly decreased,while the content of MDA kept increasing with 70 days;with the aggravation of waterlogging stress,it was less conducive to accumulate the fresh weight of ground part and root fresh weight,total biomass and underground polysaccharide content of C.pilosula.Therefore,So drainage measures should be taken timely in rainy season,and it should be ensured that at least the concentrated distribution layer of root system was not under waterlogging stress,so as to optimize the cultivation and yield of C.pilosula. |
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