燕麦幼苗对氯化钠和氯化钾胁迫的生理响应差异

为探讨燕麦对NaCl和KCl胁迫的生理响应差异,采用水培法,研究了不同浓度NaCl和KCl胁迫对幼苗生长,活性氧代谢和渗透调节的影响。结果表明:(1)在75和150mmol/L浓度下,NaCl胁迫对燕麦幼苗的膜脂过氧化伤害和生长抑制大于KCl胁迫。NaCl胁迫下叶片中的超氧化物岐化酶(SOD),过氧化氢酶(CAT)活性及可溶性蛋白、可溶性糖和脯氨酸含量低于KCl胁迫;当浓度增大到225mmol/L时,KCl胁迫叶片中O-2.,H2O2,丙二醛(MDA),可溶性蛋白和可溶性糖含量显著大于NaCl胁迫,而SOD,抗坏血酸过氧化物酶(APX)活性及谷胱甘肽(GSH)含量则相反。(2)225mmol/L KCl和NaCl处理的植株叶片水势分别为-0.867和-1.034 MPa,渗透势分别为-1.409和-1.252 MPa,说明KCl对燕麦的更强伤害不是渗透胁迫所致;经225mmol/L KCl胁迫后,燕麦叶片中Na+含量下降至对照的36.5%,而K+含量上升为对照的1.49倍,而补充20mmol/L NaCl显著提高了225mmol/L KCl胁迫下叶片Na+的含量及SOD,APX活性,降低了K+,H2O2,O-2.和MDA含量,说明离子毒害引起的活性氧积累可能是高浓度KCl胁迫对燕麦幼苗伤害大于NaCl胁迫的重要原因。

Differences in Physiological Responses of Avena Nuda Seedlings to NaCl and KCl Stress

In order to explore the differences in physiological responses of oat(Avena nuda L.) seedlings to NaCl and KCl stress, the changes in seedling growth, reactive oxygen species metabolism and osmotic adjustment in leaves of oat seedlings under NaCl and KCl stress of different concentration were investigated by hydroponics method. The results showed that:(1) At the concentration of 75 mmol/L and 150 mmol/L, NaCl stress had greater inhibition effect on the seedling growth and greater damage to the membrane lipid peroxidation than that of KCl stress, the activities of superoxide dismutase(SOD) and catalase(CAT) and the contents of soluble protein, soluble sugar and proline in the seedling leaves of NaCl stress were lower than that under KCl stress; The contents of O₂^-., H₂O₂, malondialdehyde(MDA), soluble protein and soluble sugar under KCl stress were much higher than that under NaCl stress when the concentration increase to 225 mmol/L, but the activities of SOD and ascorbate peroxidase(APX) and the glutathione(GSH) content of KCl stress were lower than NaCl stress.(2) After treated with 225 mmol/L of KCl and NaCl, the leaf water potential was-0.867 MPa and-1.034 MPa. Besides, the osmotic potential was-1.409 MPa and-1.252 MPa, respectively, indicating that the increased damage caused by 225 mmol/L of KCl was not due to the osmotic stress. Under the stress of 225 mmol/L KCl, the leaf Na⁺ content decreased by 36.5% and K⁺ content increased by 1.49 times, compared with the control, while the supplement of 20 mmol/L NaCl could increase the Na⁺ content and the activities of SOD and APX, decrease the contents of K⁺, H₂O₂, O₂^-.and MDA in leaves of oat seedlings under 225 mmol/L KCl stress significantly. The active oxygen accumulation induced by ion toxicity in oat seedling leaves could be responsible for the enhanced damage caused by 225 mmol/L of KCl than that by NaCl.