The Analysis Of Annual Changes Of Exchangeable Aluminum Concentrations In Ginseng Bed Origanted From Albic Luvisols And Ascorbic Acid Metabolism Related Enzymesm In Red Skin Ginseng

The major producer of panax ginseng(ginseng) in China is Changbai Mountain.However, Ginseng can not be cultivated continuously in ginseng bed soils.It is led tothat local farmers planted ginseng by manner of deforestation,which damaged to theecological environment of Changbai Mountain. The red skin disease of ginseng isimportant physiological diseases in ginseng bed originated from albic lucisols thatsignificantly decreased the quality and yield of ginseng. Ascorbic acid is importantantioxidant substances in plants which play an important role in plant resistance toboth biotic and abiotic stress. Based on the pre-lab works: high levels of aluminumwas contained in ginseng bed soils and red skin ginseng root tissues, as well as redskin ginseng disease associated with the oxidation of phenolic compounds,presentstudy made three years survey to evaluate the dissolution of active exchangeablealuminum in ginseng bed soils.A comparison analysis of ascorbic acid relatedenzymes was performed in health and red skin ginseng tissuse.Hydroponic cultures ofginseng seedlings were used to evaluate the Al sensitive leves of ginseng andameliorative effect of Al toxicity by exogenous application of ascorbic acid.Fieldapplications of ascorbic acid were also performed to study the relationship betweenascorbic acid and the induce of red skin of ginsengThe bed soils growing1and4years old (transplanting one year) ginsengs werecollected at September2009from the first ginseng field in Changbai Malugou ofJilin Province. We sampled the bed soils at three depths of0-5cm,5-10cm,10-15cm,and collected soil samples again in the same bed soil in September2010and2011.Measurement of physical and chemical properties of the soil found thatexchangeable aluminum concentration and pH of ginseng soil increased anddecreased respectively with elongation of ginseng cultivating period. The formernegatively correlated with the later (R=0.56, p <0.01, n=36). Exchangeable Ca andMg concentrations also decreased in ginseng bed soils. Aluminum saturation were ashigh as24%and60%at the2011and6years the ginseng soil, that respectively compared with Al saturation of17.8%,25.9%at the september of2011at the ginsengbed with3years old ginseng and6years old ginsengs respectively, which increased1.3and2.3-fold compared that at2009.Enrichment of exchangeable aluminium inginseng bed soil might result in Al toxicity in ginsengs.A comparative analysis of ascorbic acid related enzymes was conducted infibrous roots, the epidermis, cortex between the red skin ginsengs and healthginsengs.The results were as follows: the epidermis and fibrous roots of red skinginseng had higher plasma membrane peroxidation and phenolic compoundsaccummulation, and contained higher content of ascorbic acid. Determination ofactivities of enzyme related to AsA-GSH cycle found that higher enzymatic activitiesof ascorbic acid such as L-GalDH, AAO, DHAR MDHAR, GR, GST in red skinginsengs, and lower acitives of L-GalDH, AAO, DHAR MDHAR, GR, GST inhealthy ginsengs.Visible, the enzymes related to AsA synthesis (L-GalDH) andregeneration cycle (DHAR MDHAR, GR, GST) mighte be activated in red skinginseng tissues to resist oxidation process of phenolic compounds related enzyme(DHAR MDHAR, GR, GST) activity may be activated by red-color disease to resistoxidation process of phenolic compounds.Hydraponic culture showed that ginseng is sensitive to Al.10uM AlCl3in0.5mM CaCl2solution resulted in obvious H2O2accumulation. Exogenous application ofascorbic acid obviously alleviated Al toxicity. Exogenous application of ascorbic acidin the field can reduce the incidence of ginseng red skin indices and increase thebiomass of ginseng production.Thus,combing the previous work, we speculated as follows:Ginseng bed soilsoccurred aluminum toxicity. Al stress can stimulate the ginseng to produce largeamounts of phenolics and also resulted in plasma membrane peroxidation in ginsengcell. At the same time, ginseng tissues activate anti-oxidation defense system andprotect from the phenolic oxidation and Al stress by increasing the content of ascorbicacid. Phenolic compouds were oxidized to quinone that induced ginseng red skin disease.