ISSN 1002-1027  CN 11-2952/G2

Acta scientiarum naturalium Universitatis Pekinensis

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Determination of Nitrogenase Activity of Induced Cucumber Nodules by 15N Trace Method

LI Xinghong1, TIAN Dexiang1, YU Zhongju1, WANG Yongmin1, CHEN Deyuan2   

  1. 1Department of Technical physics, Peking University, Beijing, 100871; 2College of Life Science, Peking University, Beijing, 100871
  • Received:1997-03-07 Online:1997-07-20 Published:1997-07-20

Abstract: Reports the determination results of nitrogenase activity of induced cucumber root nudules by 15N trace method. The root systems bearing induced nodules of cucumber were exposed to a gas mixture containing 15N2 for 48h and partial root systems soaked in free-nitrgen culture solution simultaneusly. After exposure the 15N content in the modulated root systems of cucumber is 0.431 Atom % 15N by mass spectrometric analysis, whereas in the contrast samples without exposure to 15N is 0.369 Atom % 15N. The statiatical t test for the results of 15N trace experiments is: t=3.15 > t0.01=2.819, It has been demonstrated that the nitrogenase activity in cucumber nudules is at a remarkable level of 99.9%. The nitrogenase activity in detached nodules of cucumber was also determined by conventional acetylene reduction method. In both methods clear evidences of nitrogenase activity were obtained for the induced nodules of cucumber.