Abstract:

The measurement of the leaf area index (LAI) by plant canopy analyzer can either overestimate or underestimate the actual LAI of plant canopy. The difference between the measurement and actual LAI can differ between different instruments. The objective of this study is to analyze the errors by 2 type widely-used plant canopy analyzers' measurement of summer maize 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 are :(1) when the actual LAI<1,those estimates by LAI-2000 are higher than the actual value, but those estimates by Sunscan have no statistical difference with the actual value; (2) when the actual LAI ranges from 1 to 2,those estimates by LAI-2000 have no difference with the actual values, but the estimates by Sunscan are lower than the true value; (3) when the actual LAI>2,those estimates by both of the two instruments underestimate the actual value. (3) The correlation coefficients of LAI-2000, Sunscan estimates and those actual values are different in different crop phenological stages, with the maxima of 0.9778 and 0.9637 respectively. Then it is possible to establish the empirical models to calibrate the estimates from different plant canopy analyzers to improve accuracy.