Spectral reflectance pattern in soybean for assessing yellow mosaic disease

Area of Science:

• Agricultural Remote Sensing
• Plant Pathology
• Spectroscopy

Background:

• Yellow mosaic disease (YMD) significantly impacts soybean production in India.
• Remote sensing offers a viable method for monitoring large crop areas, but specific data for YMD is limited.
• Understanding spectral reflectance changes is crucial for disease detection.

Purpose of the Study:

• To examine spectral reflectance of soybean leaves infected with Mungbean yellow mosaic India virus (MYMIV).
• To identify specific spectral ratios or reflectance values sensitive to YMD.
• To establish remote sensing indicators for monitoring YMD in soybean crops.

Main Methods:

• Measured spectral reflectance of healthy and MYMIV-infected soybean canopies.
• Analyzed reflectance changes in visible and near-infrared regions.
• Identified sensitive wavelengths and calculated spectral ratios (R688, R750/R445) correlated with a weighted mosaic index.

Main Results:

• Significant differences in spectral reflectance were observed between healthy and infected canopies (p < 0.001).
• Infected canopies showed increased visible light reflectance and decreased near-infrared reflectance.
• Wavelengths around 642 nm, 686 nm, and 750 nm were sensitive to YMD infection, distinct from nitrogen deficiency effects.
• A shift in the red edge slope indicated chlorophyll degradation due to MYMIV.
• Reflectance at 688 nm (R688) and the ratio R750/R445 were identified as key indicators for YMD detection.

Conclusions:

• Spectral reflectance analysis can effectively differentiate MYMIV-infected soybean from healthy plants.
• The identified spectral bands (R688) and ratios (R750/R445) are reliable indicators for monitoring YMD.
• These findings enable the use of satellite data for large-scale monitoring of YMD in soybean cultivation regions.