基于叶片液泡膜电位的黄瓜钾胁迫早期诊断技术

Early Diagnosis of Cucumber Potassium Stress Based on Vacuolar Membrane Potential

为在钾胁迫症状出现之前实现黄瓜的营养诊断,用微电极技术测量4个不同钾水平处理的黄瓜叶片液泡的膜电位。研究发现钾供应不足引起黄瓜叶片液泡膜电位减小,而钾过量引起黄瓜叶片液泡膜电位增加。通过对正常钾处理(K100)与钾胁迫处理之间的黄瓜叶片液泡膜电位差的分段回归分析发现,严重钾缺乏处理(K0)2 d后,黄瓜叶片液泡的膜电位有明显减少,中等钾缺乏处理(K20)4 d后,黄瓜叶片液泡的膜电位也有明显减少,钾过量处理(K200)2 d后,黄瓜叶片液泡的膜电位有明显的增加。黄瓜叶片液泡膜电位的测量方法至少能在肉眼可见的胁迫症状出现的10d前就可实现钾缺乏或过量的营养诊断,表明用液泡膜电位对黄瓜钾胁迫叶片进行早期诊断的方法是可行的。

To achieve the pre-visual detection on potassium （K） stress,the microelectrode technique was used to measure the vacuolar membrane potential of cucumber leaves under four different levels of K-treatment. K-deficiency made the vacuolar membrane potential of cucumber leaves more negative, whereas K-excess made the vacuolar membrane potential less negative. An obvious decrease of vacuolar membrane potential could be observed after 2 d of severe K-deficiency plants. An obvious decrease of the vacuolar membrane potential could be observed after 4 d of moderate K-deficiency plants. Conversely, an obvious increase of the vacuolar membrane potential could be observed after 2 d of K-excess plants . The measurement of vacuolar membrane potential in cucumber leaf could be used for pre-visual detection of K-stress 10 d before the appearance of visually morphological changes. All of these showed that the vacuolar membrane potential measurement may be used as an early diagnosing tool for K-stress in cucumber plants. It should be pointed out that the active transport of K ＋ does not contribute to the primary generation of membrane potential but is contingent upon an electrochemical proton gradient to furnish the required energy. Ultimately, the establishment of this gradient by the activity of the plasma membrane H^＋ -pumping ATPase is the means by which plant cells become electrically polarized.