Studies On The Relationship Between Water Content And Electerical Properties Of The Leaf In Tree Specieses

In this study,we use capacitance sensor to measure the electrical characteristics of leaf,which base on the changes of dielectric canstant. And with different species of researching object, measured the capacitance changes under different water stress times. Through seeking the relationship between leaf water content and the capacitance value and found the matnematical model between them in mathematical methods, to provide a reliable thenretical and experimental basis for the instrument development and improvement. In addition, we studied water potential and electric conductivity,which can be used to diagnose water stress of plant. And also explore the relationship of water potential and capacitance values.In this experiment,we studied the electrical properties and the physioligical characteristics of Populus tomentosa Carr., Populus canadensis Moench. and Eucommia ulmoides Oliv..And we ascertain the range and testing condition in testing capacitance characteristics of these plants. On this basis,we study the impact of drought on the capacitance characteristics of these plants leaf and the relationship between capacitance characteristics and physiological characteristics.The main conclusions draw from above studiesd are:(1) leaf water content decreased with the stress time gradually extend, and the descending order in unit time is Eucommia ulmoides Oliv., Populus canadensis Moench., Populus tomentosa Carr.. The data indicate that their order of water holding capacity is Populus tomentosa Carr.> Populus canadensis Moench.> Eucommia ulmoides Oliv..(2) The best measuring frequency is 1 KHz after screened. Then we measure capacitance value of these three plants.The results show that the changes of the capacitance value is very significance,and the longer the time of water stress is,the smaller the capacitance value is.(3) Analysis of the correlation between capacitance value and water volume of leaf,water potential with SPSS 13.0 software.Results show that capacitance value are positive correlation significantly with water volume and water potential, So these three capacitance characteristics of tree could well reflect the physiological characteristics, and indirectly reflects the plant's drought situation.(4) In 1 KHz frequency, the correlation between water volume and capacitance value is significant in these three plants. In this study the regression analysis was used to analyse capacitance value and water content of these trees.Finally we fit and establish a mathematical model about capacitance value and water volume:Y= a-b X+c X2And the ranges of them are:87.055