A Handheld Multispectral Device for Assessing Leaf Nitrogen Concentrations in Maize | JoVE Visualize

Area of Science:

Agricultural Engineering
Plant Science
Remote Sensing

Background:

Accurate monitoring of leaf nitrogen concentration (LNC) is crucial for optimizing nitrogen fertilizer application in maize cultivation.
Existing methods for LNC assessment can be time-consuming, costly, or lack field portability.
Multispectral imaging offers a promising non-destructive approach for real-time crop nutritional status evaluation.

Purpose of the Study:

To develop and validate the Multispectral Soil Plant Analysis Tool (MSPAT) for assessing leaf nitrogen concentrations in maize.
To compare the performance of MSPAT against a SPAD-502 chlorophyll meter and a reference FieldSpec spectroradiometer.
To evaluate the potential of MSPAT for optimizing nitrogen fertilizer management in maize crops.

Main Methods:

The MSPAT, equipped with an AS7265x sensor (410-940 nm), was used to collect spectral readings from maize at different nitrogen fertilization levels and phenological stages.
Data analysis involved calculating normalized ratio indices (NRIs) and applying multivariate methods like Partial Least Squares Regression (PLSR) and Principal Component Regression (PCR).
Leaf nitrogen concentrations were determined using the Kjeldahl method for validation.

Main Results:

The MSPAT achieved a validation R² of 0.79 for leaf nitrogen concentration prediction, surpassing the SPAD-502 (R² = 0.70).
PLSR models using MSPAT data yielded strong predictive performance (R² = 0.75), comparable to PCR.
The developed MSPAT demonstrated effectiveness in monitoring maize nutritional status, providing results similar to a reference spectroradiometer.

Conclusions:

The portable MSPAT is a viable and effective tool for non-destructively assessing leaf nitrogen in maize under field conditions.
MSPAT offers a significant advancement over current commercial tools for crop nitrogen monitoring.
This technology supports precision agriculture by enabling optimized nitrogen fertilizer management, potentially improving crop yields and reducing environmental impact.