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 (LAIind) and corrected by the calibration variable with the LAI measured directly (LAIref). Without the proposed correction, the LAIind tended to be overestimated by 20%, on average, compared with the LAIref, for the three crops. After crop height was used to adjust the LAIind, a strong positive relationship was observed between the LAIref and the corrected LAIind (R2 = 0.96); overestimation was reduced to 4% and the root-mean-square error decreased to 0.35 m2 m-2. The variable canopy height is promising for the correction of the LAI of the soybean, corn, and sugarcane crops.

Association of Agronomic, Physiological Traits and Biomass of a Diverse Set of Sugarcane Genotypes under Varied Early Season Droughts

“…The LAI was measured (Non-destructive) using a plant canopy analyzer (LAI 2000; LICOR, Lincoln, NE, USA) following user manual recommendations for row crops between the late morning and early afternoon (LI-COR, 1992; Goncalves et al, 2020;Fattori Junior et al, 2022). The LAI was measured at three locations in each plot 3, 6, 8 and 12 MAT.…”

Process-based crop models calibration and structure affect data assimilation for estimating sugarcane yield

“…The water balance was monitored to manage the water applications and ensure crops were not exposed to water stress throughout the growing cycle; for these, irrigation was triggered every time the soil moisture reached 80% of the total available soil water. Five locations were randomly selected at the beginning of each season, where LAI samples were taken with an LAI-2200 instrument (LI-COR Bioscience), following user manual recommendations for row crops (Gonçalves et al 2020).…”

“…The experiments 1 to 3 and 16 to 22 had the LAI sampled with the LAI-2200 and LAI-2000 respectively, which had an accuracy of 4%, according to the user manual (Gonçalves et al, 2020). The other experiments had their LAI sampled with different sensors and methodology Suguitani, 2006); to maintain the response of the DA methods with the DS, we assumed the same accuracy for all observations.…”