The Research On Nondestructive Testing System For Water Content Of Populus Tomentosa Carr. Leaf

The water content of plant leaf is an important physiological index of plant water information, which has been widely used to research on plant physiology and drought resistance. Therefore, an rapidly, real-time and accurately mesasuring method for measuring water content of plant leaf is desiderated.The water content measuring techniques are analyzed and compared comprehensively in this article, and the superiority of using nondestructive testing techniques for obtaining water content of plant leaf is introduced,the application of obtaining the water content of biomass by using electrical method is discussed.With Populus tomentosa leaf for researching object, the paper introduces the research of system basing on the capacitive sensor principle, which can obtain leaf water content non-destructively. After contrasting and analyzing several measuring circuits of minute capacitance, we adopt the circuit for capacity and frequency transformation to measure the minute capacity of the capacitive sensor. SPCE061A as a core part is disigned in this system,the idea is to use the parallel-plate capacitive sensor for obtaining capacitance value of leaf water content, the capacitance value can be coverted to frequency real-time by the circuit for capacity and frequency transformation, finally the system can use the regression model between frequency and water content to calculat and display the value of leaf water content. The results show that this system can be used to measure the water content of Populus tomentosa,which can quickly obtain accurate measurement results, the ratio of measurement results that measurement error is within 5% is about 95% of the total measurement data.The development of this system can make the water content of plant leaf measured real-time, fast and non-destructively, this research is very innovative.