Physiological Response Of Chenopodium Album L. To Different Concentrations Of NaHCO₃ Stress

With the shortage of land resources,many researchers have made the improvement and utilization of saline-alkali land.The biological measures have always been the focus.Chenopodium album L.is widely distributed in the worldwide.The species not only has high nutritional value and medicinal value,but also has strong resistance in the long term adaptation to the extreme condition.The researches on C.album mainly focus on seed heteromorphism,salt tolerance,few research on the physiological response of alkali resistance.So,the growth parameters and physiological indicators of C.album were analyzed under different concentrations of NaHCO₃.The physiological mechanism of alkali resistance should be concluded.The study is thought to provide a basis for the biological improvement and utilization of saline-alkali land.In this study,C.album was used as the experimental material.The alkaline salt?NaHCO₃?was used to simulate different strength of alkali stress environment.Four concentrations were applied:50,100,150 and 200mM.In order to evaluate the response of C.album to NaHCO₃ stress,growth parameters?RWC,FW/DW,R/S,RGR?,photosynthetic parameters?contents of photosynthetic pigment,Pn,Tr,Gs,Ci,WUE?,osmoregulation contents?cationic,anionic,proline and soluble sugar?and antioxidant enzyme activities?SOD,POD,CAT,MDA?were determined.The results showed that:Under NaHCO₃ stress,the non-stomatal factor was the main factor affected the photosynthetic capacity of C.album leaves,according to the results of Pn,Gs,Ci,WUE and SPAD.Compared with the 50mM and 100mM NaHCO₃ treatment,the contents of proline and soluble sugar were significantly increased in the 200mM treatment.This indicated that when NaHCO₃ concentration reached a certain threshold,it stimulated the synthesis of proline and soluble sugar in plants.With the increase of NaHCO₃concentrations,the solute potential of different parts was decreased gradually.This was the result of Na⁺accumulation.The increase of Na⁺in different parts inhibited the absorption of various cations(K⁺,Ca²⁺,Mg²⁺)and anions(Cl^-,SO₄²-,C₂O₄^2-).NaHCO₃ stress affected the elevation of Na⁺/K⁺.C.album might try its best to control the transfer of Na⁺to the aboveground part.Finally,the highest Na⁺/K⁺in the root and the lowest Na⁺/K⁺in the leaf were recorded in the experiment.Under NaHCO₃ stress,it was necessary for the overground part?especially the leaf part?of C.album to maintain the lower Na⁺/K⁺.It is important not only for the normal physiological metabolism,but also for the resistance to salinity and alkaline.Under the low concentrations of NaHCO₃ stress,RWC,FW/DW and RGR of C.album were not significantly changed,the growth and development were not significantly affected.Under the highest concentration?200mM?,RWC and RGR were significantly reduced in order to consume more energy to cope with the effects of osmotic stress,ion toxicity and high pH environment.Compared with the control,the ratio of root to shoot was not significantly reduced.That meaned the ground part transported organic matter to the root as far as possible,in order to ensure the root provide the water,mineral elements to the ground part.In summary,it was confirmed that C.album had a certain tolerance to NaHCO₃in low concentrations,combined with the physiological parameters,growth parameters and PCA analysis.