Improving Indirect Measurements Of The Lea Area Index Using Canopy Height

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) (R-2 = 0.96); overestimation was reduced to 4% and the mean square error decreased to 0.07 m(2) m(-2). The variable canopy height is promising for the correction of the LAI of the soybean, corn, and sugarcane crops.