植物叶绿素光谱测定仪的原理与设计

Principle and design of chlorophyll spectrometry meter for plants

基于叶绿素在可见近红外波段的光谱吸收特征,以660nm红光作为叶绿素相对含量的检测依据,以940nm近红外光作为参比波长,介绍叶绿素相对含量测量原理,开发了一款便携式叶绿素诊断仪。该仪器由光源电路、光电接收电路(光电池接收面积为4mm×4mm)、单片机及外围电路等组成。经测试,红光和红外光在不同光强下,与光电池电压之间呈线性关系,线性拟合R^2为0.999、0.997。通过该仪器测定不同植物叶绿素相对值与经典比色值进行相关性比较,玉米、冬青的叶绿素a含量、叶绿素b含量以及总量与比色值呈极显著相关,R^2分别为0.759、0.750和0.770,0.806、0.771、0.796(p<0.01)。测量叶绿素浓度较高的叶片,样机测量值、SPAD—502测量值与比色值分别做相关性比较,得到R2为0.796、0.772。实验表明,该仪器可较精确地测定植物叶绿素相对含量。

Based on the absorption characteristics of chlorophyll in the visible and near infrared bands,aportable chlorophyll meter was developed with the measuring principles of relative content.660 nm monochromatic light was chosen as the reference for testing relative contents of chlorophyll,940 nm near infrared light was chosen as reference band.This instrument mainly included light source,photoelectric receiving circuit,MCU,peripheral circuit,and so on.Red and infrared lights are linear with the photodiode voltage,under different light intensities,and the R^2 is 0.999 and 0.997 respectively.After measuring relative chlorophyll values of different plants by this meter,and then compared with classical color value to calculate correlation.The results show that corn and holly’s chlorophyll a,b and total content are significant related to classical color value,and R2 are 0.759,0.750;0.770,0.806 and 0.771,0.796（p〈0.01）.In the measurement of high chlorophyll content of the leaves,the correlation between the meter measured value,SPAD—502value and classical color value are analyzed,R2=0.796 and 0.772 respectively.The experiment indicates that he relative chlorophyll content of plants could be measured precisely with this designed meter.