黄瓜幼苗对氯化钠和碳酸氢钠胁迫的生理响应差异

采用营养液培养方法，分别用不同浓度（0、25、50和75 mmol·L^-1）的NaCl和NaHCO₃对黄瓜幼苗进行胁迫处理，研究黄瓜幼苗对NaCl和NaHCO₃胁迫的生理响应差异.结果表明：随着胁迫强度的增加，黄瓜植株地上部和地下部生长量、叶片叶绿素含量和相对含水量均呈明显下降趋势，但NaHCO₃处理下降幅度大于NaCl处理.随着处理浓度的增加，黄瓜地上部Na⁺含量显著上升，K⁺含量显著下降，在相同的Na⁺浓度下，NaHCO₃处理比NaCl处理下降幅度更大，具有更低的K⁺/Na⁺.与NaCl处理相比，NaHCO₃处理的黄瓜叶片电解质渗漏率、丙二醛、脯氨酸和可溶性糖含量增加幅度更大.NaCl和NaHCO₃处理使黄瓜叶片超氧化物歧化酶、抗坏血酸过氧化物酶和脱氢抗坏血酸还原酶活性受到显著诱导，而使过氧化物酶活性受到明显抑制.

Differences of physiological responses of cucumber seedlings to NaCl and NaHCO3 stress.

By a solution culture experiment, cucumber seedlings were treated with different concentration (0, 25, 50 and 75 mmol·L^-1) NaCl and NaHCO₃, and their physiological responses were studied. The results showed that with increasing NaCl and NaHCO₃ stress, the shoot and root growth, the leaf chlorophyll content and relative water content of the seedlings decreased dramatically, and the decrements were greater under NaHCO₃ than under NaCl stress. The shoot Na⁺ content increased significantly with increasing NaCl and NaHCO₃ stress, while shoot K⁺ content was in adverse. At the same concentration of Na⁺ in culture solution, the addition of NaHCO₃ induced a greater decrement of shoot K⁺ content, and thus, a lower shoot K⁺/Na⁺ ratio. Under NaHCO₃ stress, the leaf electrolyte leakage rate and the leaf MDA, proline, and soluble sugar contents increased much greater, compared with those under NaCl stress. Under NaCl and NaHCO₃ stress, the leaf superoxide dismutase (SOD), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) activities were induced significantly, while the leaf peroxidase (POD) activity was inhibited obviously.