| Panax notoginseng?Burk.?F.H.Chen is a perennial herb of the Araliaceae family of genus Pananx.Its dry root is often used as medicine,in recent years,its stem and leaf is used by the development and utilization of a new resource food.Its traditional drug's efficacy is as follows,to stop bleeding,to promot blood circulation and pain relief,to control blood glucose,blood pressure and blood fat,etc.Yunnan province is the herb's primary producing area,95%of notoginseng in the Chinese market is provided by Yunnan.At the same time,Yunnan province is rich of mineral resources,which causes the soil heavy metal content is higher,especially Yunnan is the first cadmium producing area of China,the cadmium in the soil also deserves attention.In recent years,food cadmium pollution problem is frequent,medicinal cadmium safety is focused by Chinese medicinal materials market.How to grow notoginseng under a high cadmium background?How notoginseng response to cadmium enrichment?Is there an influence of cadmium on the growth and quality of medicinal materials of notoginseng?How notoginseng absorb cadmuium and store it?These questions all need studies to clarify.In this paper,therefore,notoginseng is used as the research object,pot culture and hydroponic experiment is used for experiment method,physiological response of cadmium enrichment and physiological mechanism of cadmium absorption is studied.The main research results are as follows:1.The growth and saponin cotent changes of 2-year-old Panax notoginseng?Burk.?F.H.Chen to cadmium stress was investigated under a pot experiment with different cadmium concentrations(0?5?10?30?60 mg·kg-1).At the same time,the speciation of cadmium in by extraction method Tessier A are tested.Results show that,The orderof five fractions of cadmium in P.notoginseng planting soil are as follows:Carb>Res>Fe-MnOX>OM>EXC,The Potential Ecological.Risk-Index assessment result showed that:cadmium in the soil is low ecological risk for environment.5 mg·kg-1 cadmium treatment can significantly promote the growth of notoginseng,and the growth parameters of notogingsen under 10 to 60 mg·kg-1 cadmium treatments are lower than blank.5 mg·kg-1 cadmium treatment can stimulate notoginseng on the absorption of N,P,K,high concentrations of cadmium inhibit its accumulation.Cadmium content in different part of P.notoginseng icreased with the increase of Cd treatment time and concerntration,the cadmium content of each part as follows:hair root>rhizome>root>leaf>stem>flowers;Cadmium enrichment coefficient of each part increased with the extension of processing time,and decresed with the Cd treatment concerntration.Cd treatment makes R1,Rg1,Re,Rb1,Rd and the sum of them lower than the blank.To sum up,the low concentration of cadmium treatment can stimulate the growth of P.notoginseng,high concentrations of cadmium can inhibit the growth of P.notoginseng,cadmium stresses will reduce the accumulation of saponins,cadmium affects medicinal quality of P.notoginseng,we should reduce the cadmium content in plant soil,to ensure the safety and quality of P.notoginseng.2.The physiological response and bioaccumulation of 2-year-old Panax notoginseng?Burk.?F.H.Chen to cadmium stress was investigated under a hydroponic experiment with different cadmium concentrations(0,2.5,5,10?mol·L-1).Result showed that low concentration(2.5 ?mol·L-1)of cadmium could stimulate the activities of SOD,POD,APX in P.notoginseng?Burk.?F.H.Chen,while high concentration(10 ?mol L-1)treatment made activities of antioxidant enzyme descended obviously.But,no matter how high the concentration of cadmium was,the activities of CAT were inhibited.The Pn,Tr,G,in Panax notoginseng?Burk.?F.H.Chen decreased gradually with the increase of cadmium concentration,however Ci showed a trend from rise to decline.The enrichment coefficients of different parts in P.notoginseng ranked in the order of hair root>root>rhizome>leaf>stem,and all enrichment coefficients decreased with the increase of concentration of cadmium treatments;while the cadmium content in different parts of P.notoginseng?Burk.?F.H.Chen and the transport coefficients rose.To sum up,cadmium could affect antioxidant enzyme system and photosynthetic system of P.notoginseng?Burk.?F.H.Chen;P.notoginseng?Burk.?F.H.Chen had the ability of cadmium enrichment,so we should plant it in suitable place reduce for reducing the absorption of cadmium;and choose medicinal parts properly to lessen cadmium intake.3.Using 2-year-old Panax notoginseng?Burk.?F.H.Chen as experimental materials,through the way of hydroponic experiment,the Cd absorption pattern and transit power,dynamic character of Cd treatment time and concerntration in P.notoginseng is studied.The results showed that:Both metabolism inhibition and transpiration inhibition can reduce the absorption and translocation of cadmium in,indicating that the absorption and transport of cadmium in P.notoginseng are both active and passive.The main absorption way to Cd of is active absorption;transpiration is the main power for P.notoginseng to transport Cd.In 0 to 2 hours into of the test,P.notoginseng absorbs Cd very quickly;2 hours later,the absorption rate is falling;24 hours later,the absorption rate becomes flat.The absorption of cadmium in P.notoginseng increases with concentration of cadmium treatment,20?mol·L-1 in this test is not the highest concerntration to Cd tolerance of P.notoginseng.4.The physiological response and bioaccumulation of 2-year-old Panax notoginseng?Burk.?F.H.Chen treated by both Cd stress and exogenous NO?SNP?or NO scavenger L-NAME was investigated under a hydroponic experiment.The results showed that 50?mol L-1 SNP treatment can reduce production rate of superoxide anion radicals O2·-and malondialdehyde content,improve the activity of SOD,POD and CAT in different parts of P.notoginseng?leaf,stem,rhizome,root?under Cd stress(10?mol·L-1);but also promote the photosynthetic efficiency and the chlorophyll content in leaves.But high concentration of SNP(100?mol·L-1)could make an opposite effect.SNP treatment can raise the Cd content and enrichment factor in P.notoginseng with the increasing concentration of SNP,while it had no effects on transfer factor.Under the treatment of NO.scavenging L-NAME and Cd,the superoxide anion radicals O2·-production rate and malondialdehyde content increased in P.notoginseng,the activities of antioxidant enzymes decreased,all the photosynthetic parameters reduced,and the content of Cd declined.Those phenomenats will increase with the increasing of L-NAME concentration.In conclusion,NO signal participated in regulating of antioxidant enzyme system,oxidative stress injury,photosynthetic system and absorption/storage of Cd in P.notoginseng under Cd stress. |
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