Effect Of Interaction Of Nitrogen And Sulfur And Sulfur Forms On Growth,Physiology And Metabolism Of Isatis Indigotica Fort.

In this paper,a pot experiment with sand culture was conducted to investigate the effects on biomass,nitrogen and sulfur metabolism,nutrient substances,active components and relative gene expression of Isatis indigotica Fort.under all possible combinations of three N treatments(N1,N2,and N3,corresponding to 5,15,and 25 mmol·L-1,respectively)and five S treatments(S0,S1,S2,S3,and S4,corresponding to 0.00,1.25,2.50,5.00 and 7.50 mmol·L-1,respectively)using split plot design.And to investigate the effect of S in different chemical forms on the growth,physiology and secondary metabolism of I.indigotica,an experiment with six treatments(CK[no added S],Na2SO4,Na2SO3,NaHSO3,Na2S and Na2S2O3)was set up,and the changes in leaf fresh and dry weight,photosynthetic physiology,nitrogen and sulfur metabolism,nutritional components and content of indigo and indirubin studied,using a pot trial.Besides,we explore the mineral elements,nutrient substances and active ingredients of Isatidis Folium and Radix Isatisis on these treatments for evaluating the quality of medicinal materails.Results were as follows.1.The two elements have obvious interaction effects and the leaf and root dry weight of I.indigotica seedlings increased greatly at N2 level.Under the same nitrogen concentration,the leaf and root dry weight increased firstly and decreased with the rising of sulfur concentration in which S2 was conducive to the growth and biomass accumulation.Soluble sugar,soluble protein,soluble amino acids contents are the highest in N1,N2 and N3 level,respectively.The influence of sulfur concentration on nutritional components is same as biomass,but the peak of different nutritional components was diversity in different nitrogen levels.The effects on secondary metabolites(total flavones,indigo,indriubin,epigotrin contents)were not obvious significantly,in which these indexs by N1S3,N1S2,N3S0,N3Slwere the highest,respectively.2.Significant differences in enzyme activities and related gene expressions were detected at different application levels of N and S.The NR activity was positively correlated with the N application level,while the GS,GDH,and GOGAT activities were negatively correlated with the N application level.The relative expression of NR,GDH and GOGAT gene were highest in N3,N2 and N1 level,and it was consistent with the change of enzyme activity.The effect of nitrogen on sulfur metabolism enzymes was different in various sulfur levels.For example,APR activities were lowest in N1 level,while the expression of the APR gene was the highest.The activities of enzymes involved in the metabolism of N and S increased at low S application levels,and decreased at higher S application levels.The effects of S application on the expressions of genes involved in N and S metabolism enzyme gene had no obvious regularity.3.It was found that the fresh and dry weight were greatest in the Na2SO4 treatment,with the NaHSO3 treatment being second highest.Compared with CK,the other S treatments did not significantly promote biomass accumulation.The net photosynthetic rates and chlorophyll contents in sulfur treatments were higher than those observed in CK,and the highest observed net photosynthetic rate and chlorophyll contents occurred in the NaHSO3 and Na2S,respectively.Na2SO3 and Na2SO4 increased the activities of nitrogen and sulfur metabolism enzymes respectively compared to other treatments,with the CK being no inhibiting obvious in their effect.The responses of nutritional components to sulfur forms differed.Soluble protein and soluble amino acid concentrations were decreased in CK plants compared to S-treated plants,with the highest soluble protein,free amino acid,and soluble sugar concentrations observed in the NaHSO3,Na2SO4 and NaHSO3 treatments,respectively.In contrast to the physiological responses,the levels of secondary metabolites indigo and indirubin were the highest in Na2S treatment.4.The total dry weight of leaf and root were increased by the increasing of nitrogen concentration and the highest dry weight was found in N3S3 treatment.Under different nitrogen levels,the contents of K,Ca,P,Mg were difference in various S concentrations,its contents were first increased and then decreased with the increasing of S concentration.Micro-elements(Fe,Mn,Zn)were highest in 25.00 mmol·L-1,while there was no influence in its contents under different S concentrations.Soluble amino acids and soluble sugar contents were highest in N3 and N2 level,respectively,but its contents were increased firstly and decreased with the rising of sulfur concentrations.Total flavonoids contents were highest in N1 level in Isatidis Folium and N3 level in Radix Isatidis.Indigo,indirubin and epigiotrin contents were the highest in N2S1,N1S4 and N2S1 treatments,respectively.5.Applying different forms of sulfur,the leaf and root dry weights were greatest in the Na2SO4 treatment,while Na2S and Na2S2O3 hindered the growth of I.indigotica.The content of macro-elements(P,K,Ca,Mg)in leaf were highest in Na2S,CK,Na2SO3 and Na2S2O3 treatments,respectively.But,in the root,the content of P,K,Ca,Mg were highest in Na2S,Na2SO3,Na2SO4 and CK treatment,respectively.The micro-element contents(Fe,Mn,Zn)were mainly the greatest in Na2S treatment.Soluble amino acid concentrations in leaf were highest in NaHSO3 treatment,and lowest in CK treatment.It was highest in Na2S treatment and other treatments had no significant difference in the root.Soluble sugar in leaf,Na2SO4 treatment was the lowest,the rest showed no significant difference.And it was highest in Na2SO3 and Na2S treatments in root.The content of total flavonoids in leaves and roots was maximized by Na2SO4 and Na2SO3 treatments,respectively.Indigo and indirubin were respectively maximized by Na2SO4 treatments,while epigoitrin was maximized by Na2SO3.