The Studies On Biological Basis And Application Of Electrical Indexes Assessing Tree Health

The study was supported by National Nature Science Foundation of China of "Biological foundation study of electrical indexes assessing tree vigor". The mechanism of tree's leaf and stem capacitance and the application of electrical indexes under environmental stresses were studied. The main conclusions are summarized as following:(1) The leaf capacitance had significant positive correlations with leaf exosmosis electro conductivity, exosmosis percentage and leaf absolute moisture content, had significant negative correlations with leaf electrolyte electro conductivity and had no correlations with leaf relative water content (RWC).(2) The stem capacitance had significant positive correlations with DBH(diameter at breast height) and bark relative turgidity (RT). The electrical capacitance of redistilled water was much lower than that of KCl solution and the electrical impedance of redistilled water was much higher than that of KCl solution. The electrical capacitance and impedance of sucrose solution were similar to that of redistilled water. The conception of "unit capacitance" was proposed, unit capacitance is determined by the ratio of tree stem capacitance to diameter.(3) The influence of biological stresses of poplar canker on the electrical indexes of trees was studied. The results showed that the activity of peroxidase (POD) increased and than decreased, activity of polyphenoloxidase (PPO) and tree stem impedance increased gradually, tree stem capacitance and unit capacitance decreased after Populus tomentosa Carr. cuttings was infected with Botryosphaeria sp. . The statistical difference of POD was showed firstly, the second index was tree stem capacitance, the third one was tree stem impedance and the last one was PPO.(4) The influence of biological stresses of pine wood nematode on the electrical indexes of trees was studied. Tree stem capacitance and unit capacitance had significant positive relationship with the ratio of dead leaves to all leaves. The correctness rate could reach 90.32% when 0.5nF threshold of tree capacitance was used to estimate whether the Pinus massoniana Lamb, was infected with Bursaphelenchus xylophilus.(5) The influence of intraspecific competition stresses on the electrical indexes of trees was studied. The results showed that the stem diameter, height, tree stem capacitance and unit capacitance of high density treatment were significantly lower than that of low density treatment, while the tree stem impedance was significantly higher than that of low density treatment.(6) The influence of intraspecific competition stresses on the electrical indexes of trees was studied.The results showed that the trends of decrease of activity of SOD and increase of content of MDA and soluble sugar of all the treatments were observed from the third day when the cuttings of Populus tomentosa Carr. were applied with drought stress. The trends of decrease of tree stem capacitance and increase of tree stem...