柑橘叶面积指数自动测量红外透射系统的开发与应用

针对间接方法测叶面积指数(leaf area index,LAI)一般不考虑单一孤立果树冠层、叶片相互重叠因素及图像处理速度低的缺点,通过正交试验确定单一孤立柑橘LAI测量的主要影响因素为重叠叶片数(α<0.05),建立等间隙模型解决有间隙的重叠的影响问题,采用三维行走机构实现自动采集,应用LabVIEW平台开发一个基于红外透射的柑橘LAI自动测量系统。系统硬件由控制模块与行走机构、信号调理模块、数据采集卡和PC机组成,其标定LAI相对误差绝对值平均为11.11%。在行走机构按照S形路线,自动进行扫描、定位采集的方式下,系统对华南农业大学工程学院柑橘园45棵橘树测量,以直接法和采样法计算的LAI值作为真实值,相对误差绝对值的平均为31.4%;参照对比的Win SCANOPY Pro植物冠层分析系统专业版测量值与真实值比较,相对误差绝对值的平均为29.8%。两系统误差接近,表明本系统可满足柑橘LAI测量试验要求。

Development and application of citrus LAI using infrared transmittance technique

To solve the shortcomings of indirect LAI measurement methods which seldom considered the factors of single isolated canopy,leaves overlapping each other and the image processing speed slowly,the intermittent model avoiding leaves overlapping was established based on the main influential factor of single isolated citrus fruiter LAI’S measuring system(α<0.05) by orthogonal experiment.Then automatic acquisition possible was realized by adopting three dimensional walking mechanisms,and an automatic measuring system of citrus LAI was developed based on infrared transmission using the LabVIEW platform.The hardware system was composed of control module,running gear,signal conditioning model,data acquisition card and PC,of which the demarcated average absolute relative error was 11.11%.With the running gear scan,locate and collect automatically in S shape,45 citrus trees in the citrus garden of the College of Engineering of South China Agricultural University were tested.With the LAI value computed from direct method and sampling method as true values,the average absolute relative error was 31.4%.Compared with true values,average absolute relative error of the measured value from plant canopy analysis’s professional version was 29.8%.Since the errors of the two systems were similar,the system proposed could meet the requirement of LAI test.