Design Of Crop Leaf Moisture Content Measuring Instrument Based On Multi-Electrical Parameters

Leaf is one of the most important organs in plants and crops,and it plays an irreplaceable role in respiration,photosynthesis,transpiration and nutrient transformation.Leaf moisture content detection is helpful to master the growth states of the crop,and provide guidance for irrigation,fertilization and other production management.At present,there are three types of water content detection technology of the leaves.The first method is using physical method to measure and compare the leaf weigh before and after dehydration,the results are accurate,but the detection cycle is long,and the structure of the crop is destroyed.The second method is based on the relationship between spectral characteristics of the leaves and water content,the detection cycle is short,but the cost of measuring instruments is generally high,the measurement results are affected by the external environmental factors.The third method is based on the electrical parameters of leaves,the relevant research is not deep enough,but has broad application prospects.It has great significance to research and develop the crop leaf moisture content testing instrument with good performance,convenient to use and price moderate.In this dissertation,a portable and fast measuring instrument of crop leaf water content was developed and produced.The STM32F103 Z microprocessor served as CPU,in the case of control pressure of electrodes to the leaf,two electrophysiological parameters,capacitance and resistance,were measured,and the water content was obtained by constructing the test model.The main work is as follows:1)Development of portable measuring instrument.Including hardware design,software design and instrument production,to achieve environmental temperature measurement,electrode pressure measurement,blade capacitance and resistance value measurement,control and display functions,and the measurement of contrast experiments and error correction to ensure that the measurement error within the acceptable range.2)Construction of water content detection model.The capacitance,resistance and true moisture content of wheat leaves were obtained by experiments.The data was processed by Matlab,and the detection model was established.3)Crop leaf moisture content test.The water content of wheat leaves was measured by using the developed instrument and the water content model,and analyzed the error.