Inlfuence Of The UV-B Radiation And Drought To The Biomass And The Phenolic Constituents Content Of The Salvia Miltiorrhiza

The stratospheric ozone loss is one of the global environmental problems, which drawsthe popular attention. The ozone is the only matter in the atmosphere to absorb the ultravioletradiation. Because of the stratospheric ozone loss, the UV-B radiation (280-320nm） reachesthe earth increasingly, which is vital to the plant. The most pronounced influences of theUV-B radiation to the plant are the UV-B absorbing matter, the morphology characters and thephotosynthesis effects. With the antioxidative property, the phenolic constituents are the mainUV-B absorbing matter and are the medicinal active components of many medicinal plants.Therefore, the research on the biomass and the phenolic constituents of the medicinal botanyunder the added UV-B radiation has theory and practical significance.The Salvia miltiorrhiza Bunge, as the Chinese traditional popular medicine, is cultured tocater to the market demands. There are two major groups of active constituents in the S.miltiorrhiza, water-soluble phenolic constituents and fat-soluble tanshinones. Tradditionally,the S. miltiorrhiza roots are used as the medicine, whereas the leaves which contain abundantphenolic constituents according to the latest reports are always ignored. The leaves areirradiated by the UV-B light directly, the influences of the UV-B to the biomass and thephenolic constituents of the S. miltiorrhiza leaves provide the new resource for getting thenatural antioxidant matters.This paper regarded the medicinal plant S. miltiorrhiza as the object, took the artificalsimulating the enhanced UV-B radiation by using the UV-B lamps in the growth room and thesunshade,(simulating the increased16%and26%UV-B radiation of the natural UV-Bintensity in Xiaan city), studied the long (UV-B radiation82d)and short period (UV-Bradiation18d and50d) irradiation effects of different intensity of UV-B radiations on themorphology, photosynthesis effect and the phenolic constituents of the S. miltiorrhiza,explored the response of the S. miltiorrhiza to the different growth periods and the variousorgans to the different UV-B radiation intensities, and the diverse responses of differentaltitude origined species to the UV-B irradiation. The aims were to reveal the morphology andphysiology adaptation mechanisms of the Salvia to the UV-B radiation, and the responsestrategies of the plant to the drought and the UV-B radiation acted alone and combined. The main conclusions mentioned below:(1) UV-B caused the free radical accumulated, the membrane lipid peroxidated, thephenolic constituents increased in the S. miltiorrhiza leaves. What’s more, the effect of thehigh level of UV-B radiation（950J·m-2·d-1） was more evident than that of the low level ofradiation（560J·m-2·d-1）. The S. miltiorrhiza developed the different strategies to the variousUV-B radiation intensities, under the low UV-B radiation, the antioxidative enzymes were thedominant, but with the radiation intensified, the phenolic constituents and the enzymes actedcoefficient to protect the plant.(2) The sensitive responses of the low altitude (average elevation2154m) origined S.miltiorrhiza (Danshen) and the high altitude (average elevation3100m) origined Salviacastanea Diels.ftomentosa (Zangdanshen) were various to the UV-B radiation. The SABcontent of the former was higher than that of the latter, the SAB content in the Danshenreached to2.47times of the Zangdanshen control and2.85times of the Zangdanshentreatment. The Danshen responsed more sensitively to the UV-B radiation, the antioxidantsand the antioxidative enzymes combined acted to against the hurt from the UV-B radiation,the Vc content and the APX activity were enhanced significantly. The sensitivity indexindicated that the high altitude origined Zangdanshen (SI=0.51) was more tolerant to theUV-B radiation that the low altitude origined Danshen (SI=1.12), which is meaningful forfostering the tolerant species to the high UV-B radiation.(3) We researched the influences of the UV-B radiation and the drought alone to the S.miltiorrhiza, results indicated that the influence of the UV-B radiation was more significant tothe growth and the phenolic constituents than that of the drought. UV-B radiation induced theheight, leaf area, the shoot biomass and the root biomass decreased sharply. The SAB and RAtotal contents of the roots under the UV-B radiation reduced by93.72%and90.15%. Underthe drought condition, the leaf area decreased markedly, the shoot and the root biomassincreased in the middle drought（55%FC）, and decreased in the heavy drought（40%FC）.The SAB and the RA total contents of the roots under the drought were decreased by28.49%and18.61%. The trendency of the shoot biomass and the root biomass were the same underthe UV-B radiation or the drought. UV-B radiation caused the SAB and the RA contentsincreased427.78%and800.00%respectively, but the drought induced the SAB and RAcontents increased112.22%and151.43%. Because the phenolic constituents varied with theposition of the leaves on the plant, evaluating the total contents of the phenolic constituents ofthe leaves need the futher research. This reasech indicated that people can get more naturalantioxidant materials from the S. miltiorrhiza leaves by exerting suitable UV-B radiation. Theeffects of the UV-B radiation to the total phenolic constituents’ yields of the S. miltiorrhiza roots were more than that of the drought, SAB total yield reached the most68.96ug under the75%CK treatment，while it got the minimum4.33ug with the75%T2treatment. RA totalyield had the maximum10.29ug under the55%CK treatment，while it was only0.84ug withthe40%T2treatment.(4) The research manifested that the combined effects of UV-B radiation and the droughtto the S. miltiorrhiza were complicated reinforce or offset, drought depressed significantly theeffect of the UV-B to the S. miltiorrhiza, and with the drought intensity intensified theinhibition was reinforced. The low UV-B（2.60KJ·m-2·d-1）depressed the effect of the drought,but the high UV-B （4.10KJ·m-2·d-1）intensified the effect of the drought. With theantioxidative character, the increased phenolic constitutes under the UV-B radiation wereuseful for improving the tolerence of the S. miltiorrhiza. The complicated interaction of thetwo factors could be connected with the crosstalk of the UV-B and the free radical signaltransduction, which still needs further research.(5) The leaves of the S. miltiorrhiza are suffered from the UV-B radiation directly, theresearch of UV-B radiation to the phenolic constituents in different growth periods wasimportant for incrasing the natural antioxidants yield with artificial regulation. The researchcompared the response diversity of the shoot rapid growth former period (On June7,2011)with the latter period (On Auguest12,2011) after the UV-B radiation18days. The resultsshowed that the sensitivity of the S. miltiorrhiza to the UV-B radiation depended on theradiation intensity and the growth period. Because of the priming effect, the low UV-B wasmore contributed to increasing the phenolic constituents. The phenolic constituents in theshoot rapid growth latter period were higher than that in the former period, so the plant of theformer period were more sensitive than the latter. The young leaves responded to the UV-Bradiation rapidly. With the radiation reinforced, the plant became less sensitive in the formerperiod. The membrane of the leaves were hurt in the latter period under the high UV-Bradiation and the stability of the membrane system declined, which had the sensitivity of theplant to the UV-B radiation increased.(6) The research compared the sensitivity indexes of the long term UV-B radiation to theplant (the rapid growth period: UV-B radiation for50days; and the harvesting period: UV-Bradiation for82days), the results indicated that S. miltiorrhiza was the sensitive species to theUV-B radiation. It became more sensitive with the UV-B radiation intensified and theradiation prolonged. The plant appeared shorten, leaf area decreased, biomass decreased andthe SAB and the RA contents increased in the leaves. These characters were benefit for plantadapting the UV-B radiation. Whereas the decreased biomass were the results of thephotosynthetic apparatus damage caused by the UV-B radiation. UV-B induced the SAB and RA total contents reduced sharply in the roots of the S. miltiorrhiza. So, in the filedmanagement of the S. miltiorrhiza, shading the sunlight moderately will be useful to enhancethe biomass and the total medicinal components yield.Above all, the added UV-B radiation has the obvious depression effect to the biomassand the medicinal total contents of the S. miltiorrhiza, but the phenolic constituents in theleaves of the S. miltiorrhiza were enhanced significantly, which may be the new resource ofthe natural antioxidants. This paper researched the effects of the UV-B radiation to thedifferent growth periods with the different radiation intensities. Which provided the theorticalbase to improve the field management measures and control artificially phenolic yields.