As胁迫对二年生三七生长、根部As含量和根系分泌物的影响

Effect of As stress on the growth,the root As contents and root exudates in 2-year-old Panax notoginseng

通过大田试验,研究不同As处理浓度(As5+:0、20、80、140、200、260mg/kg)下,二年生三七绿果期生长特征、根不同部位(主根、须根和剪口)As含量和根系分泌物中有机酸含量、可溶性糖含量和游离氨基酸含量的变化规律。结果表明:(1)株高、叶面积和生物量随着砷处理浓度的增加降低,砷处理浓度为260mg/kg时,根生物量降低26.47%,总生物量降低23.61%;(2)主根、须根和剪口砷平均含量分别0.38、2.51、0.44mg/kg。三七根不同部位砷含量依次为:须根>剪口>主根;(3)砷胁迫条件下,根系分泌物中柠檬酸和总有机酸含量随砷处理浓度的增加而增加,醋酸和琥珀酸含量随砷处理浓度的增加而降低,在砷≥80mg/kg时,根系不再分泌苹果酸和乳酸;(4)根系分泌物中可溶性糖和游离氨基酸含量随砷处理浓度的增加而增加。总之,二年生三七的生长、砷含量和根系分泌物的组成和含量受到砷胁迫的影响,As大于140mg/kg处理时,三七的生长受到抑制,As小于200mg/kg处理时,柠檬酸、可溶性糖和游离氨基酸含量随As处理浓度的增加而显著增加。

In this study,in order to explore the effects of different As concentrations(As5+:0,20,80,140,200,260mg·kg-1)on2-year-old Panax notoginseng,the growth characteristics,the As contents in different root parts,and the contents of organic acid,soluble sugar,and free amino acid in root exudates were investigated green fruit stage.The results showed that:(1)The plant height,leaf area,and biomass decreased with the increase in treatment concentrations of As.The root and total biomass decreased by 23.61%and 26.47%respectively at the As concentrations of 260mg·kg-1.(2)The average As contents of main root,fibrous root,and rhizome were 0.38mg·kg-1,2.51mg·kg-1,and 0.44mg·kg-1 respectively,so the order of As contents in different parts was fibrous root>rhizome> main root.(3)Under As stress,with the enhancement of treatment concentrations of As in root exudates the contents of citric acid and total organic acid increased,while the contents of acetic acid and succinic acid decreased gradually.When the treatment concentrations of As reached 80mg·kg-1,Malic and lactic acid were not secreted.from root.(4)The contents of soluble sugar and amino acid of root exudates increased with the increase in treatment concentrations of As.In sum,the growth,As contents of root,and the composition of root exudates in 2-year-old P.notoginseng were influenced by As stress.The growth was inhibited when the treatment concentrations of As exceeded 140mg·kg-1,and the contents of citric acid,soluble sugar,and free amino acid in root exudates increased with the increase in treatment concentrations of As when As concentrations were less than 200mg·kg-1.