碱胁迫下冰草根系pH值与有机酸含量变化

Study on the Relationship between pH and Organic Acid in the Root of Agropyron cristatum Tawukumu under Alkaline Stress

【目的】研究塔乌库姆冰草耐碱性机理,分析根系分泌的有机酸与pH值在调控植物抗碱性之间的关系。【方法】将2种碱性盐Na_(2)CO_(3)、NaHCO_(3)按摩尔比9∶1混合,人工模拟10、30、60、90、120 mmol/L天然碱性生境条件对塔乌库姆冰草幼苗进行碱胁迫,测定pH值与有机酸种类及含量,分析其对胁迫的生理响应。【结果】碱胁迫导致塔乌库姆冰草胚根、胚芽生长缓慢,其中胚根生长率仅为对照的0.40倍,受到明显抑制;随处理液浓度的增加,幼苗根系分泌以苹果酸、柠檬酸为主的有机酸,使植物根系内pH保持在6.65~6.68。冰草根系分泌的有机酸在碱胁迫过程中虽然明显增加,但不能阻止高浓度的pH对植物幼苗的伤害。【结论】碱处理液浓度为60 mmol/L,即pH为9.8时,有机酸分泌量为调控冰草根系pH最适宜浓度。

【Objective】To study the mechanism of alkali resistance of Agropyron cristatum'Tawukumu'and the relationship between organic acids secreted by roots and pH value in regulating alkali resistance of the plants.【Methods】Two kinds of alkaline salts Na_(2)CO_(3) and NaHCO_(3) were mixed at a molar ratio of 9∶1.Alkali stress was simulated by artificial simulation under natural alkaline habitat conditions of 10,30,60,90 and 120 mmol/L.The pH value and organic acid species and content of the seedlings were determined to study their physiological response to stress.【Results】Under alkaline stress,the radicle and embryo of Agropyron tawukumensis grew slowly,and the radicle growth rate was only 0.40 times that of the control,which was more significantly inhibited.With the increase of the concentration of treatment solution,the roots of seedlings secreted organic acids mainly malic acid and citric acid,which interacted with each other to resist the damage of high pH to plants kept the pH in the roots between 6.65 and 6.68.Although the organic acids secreted by the roots of Agropyricacrassifera increased significantly in the process of alkali stress,they could not prevent the damage of high pH to the plant seedlings.【Conclusion】When the concentration of treatment solution is 60 mmol/L,that is,the pH value is 9.8,the organic acid secretion was the most appropriate concentration to regulate the pH value of Agropyricacrassifera root.