| Rehmannia glutinosa Libosch.,a member of Scrophulariaceae family,is a perennial medicinal herb with a wide range of medicinal properties.It is used in medicine for its dry root,which is one of the four famous Chinese medicines in China.Jiaozuo City,Henan Province,in central China,is the authentic production area of R.glutinosa with the best quality.Unfortunately,R.glutinosa has serious replant problem in production.It can not be continuously planted in the same farmland till 8-10 years of other crops cultured.The output can not meet the market demand,which seriously limits the development of Rehmannia glutinosa Industry.Now no measures have been found to effectively solve replant problems.Previous studies have shown that the main cause of the replant problems of R.glutinosa is the allelopathic autotoxins produced by the secondary metabolic process.UV-B radiation can change the secondary metabolic process in plant.Then,by carrying out UV-B radiation to R.glutinosa,can it change the secondary metabolic process of R.glutinosa and reduce the production of allelopathic autotoxins.In this study,R.glutinosa in natural environment was subjected to 13?w/cm~2(15%of simulated natural UV-B)UV-B irradiation,which study the effect of enhanced UV-B radiation on the growth,physiological,biochemical and secondary metabolic processes of R.glutinosa.It is to explore whether UV-B radiation can change the metabolic process of Rehmannia glutinosa and reduce the production of allelopathic toxic compounds to alleviate replant problems of R.glutinosa.Through the observation of the growth of R.glutinosa,the determination of physiological activity indicators and the content of secondary metabolites.The main conclusions are as follows:(1)The effects of UV-B on the morphological structure of Rehmannia glutinosa.Rehmannia glutinosa in natural environment was supplemented with low-dose UV-B irradiation,and the surface microstructure of leaf was observed by scanning electron microscopy.It was found that UV-B irradiation had different effects on the stomatal density and glandular trichome number of different leaf ages,which can significantly reduce the number of glandular trichomes and stomata density in young leaves,and increase the number of glandular trichomes and stomata density of mature leaf(L3,L5).After UV-B irradiation,the epidermal cells of R.glutinosa leaf was shrunk,but there was no difference in glandular trichome size.UV-B treatment had no significant effects on the aboveground and underground morphology of R.glutinosa,as well as biomass,such as leaf length,leaf width and root diameter.However,under the UV-B treatment,the leaf area decreased by 12%,and the leaf thickness increased,indicating that the plant can respond to UV-B stress through morphological changes.(2)The effects of UV-B on the medicinal components of Rehmannia glutinosa.The results of this experiment showed that UV-B radiation can significantly promoted the synthesis and accumulation of verbascoside and catalpol in root of Rehmannia glutinosa,and also promoted the accumulation of verbascoside and catalpol in leaf of Rehmannia glutinosa,but it does not reach significant difference.It shows that enhanced UV-B radiation had certain benefits in improving the medicinal quality of Rehmannia glutinosa.(3)The effects of UV-B on the physiological activity of Rehmannia glutinosa.In this study,although enhanced UV-B radiation had no significant effect on chlorophyll content,root activity,and MDA content in leaf of Rehmannia glutinosa,it could significantly increase the flavonoid content to absorbing excess ultraviolet rays,and also increasd activity of CAT and activity of PAL.(4)Preliminary study on effects of UV-B on replant problems.After analysis,UV-B irradiation did not significantly inhibit the growth and physiological metabolism of Rehmannia glutinosa,but it also failed to promote the accumulation of Rehmannia glutinosa biomass.However UV-B could promote the accumulation of verbascoside and catalpol in Rehmannia glutinosa. |
PDF Full Text Request