Development Of Chlorophyll Meter With Leaf Thickness Compensation

The nitrogen nutrition status can be diagnosed through quantizing the chlorophyllcontent. However, the reading of SPAD chlorophyll meter is affected by the difference of leafthickness. Therefore the SPAD chlorophyll meter needs thickness compensation to eliminate theinfluence of leaf thickness difference. This paper carried out the research on the chlorophyllmeter with leaf thickness compensation, combining with Advanced Sensor and Precision TestingTechnology, Photoelectric Detection Analysis Technology, Modern Plant Physiology and someother subject areas.The main research works are shown as follows:Firstly, the chlorophyll meter with leaf thickness compensation was developed. TheSPAD’ mathematical model with the leaf thickness compensation was put forward, The fixturemeasuring device and hardware circuit for this chlorophyll meter were designed, the softwareprograms and the PC interface were wrote, which realize the accurate measurement of leafthickness and the chlorophyll content.Secondly, in order to explore the influence of leaf thickness difference on the chlorophyllmeter estimating the chlorophyll content, The leaf thickness, SPAD, chlorophyll content of riceand cotton leaves with leaf thickness difference were measured, and the relationships amongthem were analyzed; In order to analyze the chlorophyll content detection accuracy of theinstrument, and evaluate the chlorophyll content estimating ability of SPAD′mathematicalmodel after leaf thickness compensation, the correlation of the SPAD and chlorophyll contentbefore and after leaf thickness compensation in cotton and rice different growth period wereanalyzed; In order to diagnose the best leaf measuring position and point, the SPAD level ofcotton in different growth periods was measured.The results were showed that: the bigger leaf thickness can make the SPAD reading larger;The instrument developed in this article had high detection accuracy of chlorophyll content, theaverage relative error were mainly less than1%, and the correlation between SPAD value andchlorophyll content was much more significant after the leaf thickness compensation, thecorrelation coefficient were mainly above0.8after compensation; The best leaf position and measurement point were fourth leaf and leaf tip.Finally, the cotton regression models of chlorophyll content, leaf thickness and SPAD influid phase was established, the regression analysis and significance test were carried on, and thepredicted value and the real value were analyzed.The research of this paper can provide the experimental and theoretical basis for improvingthe crop nitrogen application level and realizing the precision agriculture...