Research On Physiological Characteristics Of Chenopodium Quinoa Willd.under Salt-alkali Stress

The area of salt-alkali soil is increasing in all regions of the world.Salt-alkali stress is one of the major abiotic stresses,which affects plant growth and crop yield.In nature,the neutral salt and alkaline salt often coexist.Due to the higher pH value caused by alkaline salt,the harm to plants is much greater than the neutral salt stress.Therefore,the effects of salt-mixed stress on plants and their resistance mechanisms have been paid more and more attention.Quinoa?Chenopodium quinoa Willd.?is a natural Andean crop,and has gathered much attention for its many uses and rich nutrients.At present,the research on quinoa is mainly focused on neutral salt stress and drought stress.The effect of salt-alkali on the growth of quinoa and the resistance mechanism have not been widely concerned.This research attempts to explore the effect of salt-alkali on the physiologaical mechanism of quinoa through photosynthetic characteristics,antioxidant mechanism and osmotic adjustment,analysis the effect of salt-alkali on the growth of quinoa,and to reveal the physiological mechanism of quinoa under salt-alkali stress.In this study,quinoa?Titicaca?was used as the experimental material.Different concentrations of NaCl and NaHCO₃ salt-mixed?100,200,300,400 and 500 mmol·L-1?were chosen.The physiological indexes were as follows: growth parameters?RWC,RGR,R:S and FW:DW?,photosynthetic parameters?photosynthetic pigment,stomatal density,gs,Pn,Tr,Ci?,the activity of antioxidant enzymes?SOD,POD,CAT and MDA?and the content of osmotic adjustment substances?ions,organic acid,proline and soluble sugar?.The results showed that quinoa has good water retention ability and ability to adapt to salt-alkali stress suitable concentration salt-alkali conditions.By increasing the photosynthetic pigment content and Mg2+,increased stomatal conductance,effectively regulate the balance of water and gas exchange,promote leaf photosynthesis,increase water use efficiency of quinoa.The higher activity of POD and CAT to maintain the balance of ROS,reduce the production of MDA,to ensure the normal physiological function of cell.Ion absorption and effective area,organic acid percentage adjustment,organic osmatics?proline and soluble sugar?made an important contribution of quinoa under low concentration salt-alkali stress.Quinoa can increase tolerance to salinity stress by maintaining specific physiological metabolic pathways under high stress conditions.To keep normal growth and development,the seedlings of quinoa improved the activity of antioxidant enzyme,synthesized and accumulated of inorganic ions and organic substances to maintain the water balance and the pH stability of internal environment,and increased the photosynthetic rate under the suitable salt-alkali conditions.Our results confirmed that the quinoa has better physiological mechanisms to adapt salt-alkali environment.