Improving indirect measurements of the leaf area index using canopy height

Abstract

The objective of this work was to evaluate the use of plant height as a calibration variable for improving indirect measurements of the leaf area index (LAI). Three experiments were conducted with different crops – corn (Zea mays), soybean (Glycine max), and sugarcane (Saccharum officinarum) –, to compare the performance of the LAI measured indirectly (LAI_ind) and corrected by the calibration variable with the LAI measured directly (LAI_ref). Without the proposed correction, the LAI_ind tended to be overestimated by 20%, on average, compared with the LAI_ref, for the three crops. After crop height was used to adjust the LAI_ind, a strong positive relationship was observed between the LAI_ref and the corrected LAI_ind (R² = 0.96); overestimation was reduced to 4% and the mean square error decreased to 0.07 m² m^-2. The variable canopy height is promising for the correction of the LAI of the soybean, corn, and sugarcane crops.