两种植物冠层分析仪测量夏玉米LAI结果比较分析

植物冠层分析仪测量作物叶面积指数存在高估或低估现象，不同仪器的测量结果均与真实值存在差异，这种差异除了与仪器有关，还在不同的作物物候期表现出不同规律。本研究使用LAI-2000、Sunscan两种主流植物冠层分析仪测量夏玉米不同生育期LAI，并与LI-3000C叶面积仪实测结果比较。研究发现：当玉米LAI<1时，LAI-2000测量结果高于实际值，Sunscan测量结果与实际值无显著差异；12时，两种冠层分析仪测量结果均低于实际叶面积指数；不同LAI范围内，LAI-2000、Sunscan测量值与实际值的相关系数不同，最高可达0.9778和0.9637，通过建立测量值和实际值的经验关系模型，对仪器测量值进行校正可减少误差。

Evaluation on the Measurement Errors of Summer Maize LAI by Two Different Plant Canopy Analyses

The objective of this study was to analyze the errors by 2 type widely-used plant canopy analyzers＇ measurement of summer maize leaf area index （LAI）. In this study, we compared the measurements of LAI by LAI-2000 and Sunscan with the measurements by LI-3000C leaf area meter in 4 different phenological stages of summer maize. The main findings of this research were： when the actual LAI1, those estimates by LAI-2000 were higher than the actual value, but those estimates by Sunscan had no statistical difference with the actual value; when the actual LAI ranges from 1 to 2, those estimates by LAI-2000 had no difference with the actual values, but the estimates by Sunscan were lower than the true value; when the actual LAI2, those estimates by both of the two instruments underestimate the actual value. The correlation coefficients of LAI-2000, Sunscan estimates and those actual values were different in crop phenological stages, with the maxima of 0.9778 and 0.9637 respectively. So we can draw a conclusion that different plant canopy analyzers have different rule of measurement error in crop phenological stages. Then it is possible to establish the empirical models to calibrate the estimates from different plant canopy analyzers in different LAI condition to improve accuracy.