Table 1 Summary of sensors that have been used for phenotyping PPI
From: Sensor-based phenotyping of above-ground plant-pathogen interactions
Sensor, technology | Imaging/non-imaging | Active/passive | Effect measured | Excitation/illumination wavelengths | Measured wavelengths |
|---|---|---|---|---|---|
Monochrome | Imaging | Mainly active | Reflectance | Variable | Variable |
RGB | Imaging | Mainly active, passive at large scale | Reflectance | Variable, usually visible spectrum | Range: ~ 400–700 nm R: ~ 600 nm G: ~ 530 nm B: ~ 460 nm |
Hyperspectral | Both | Mainly active, passive at large scale | Reflectance, transmission | Variable | 400–2500 nm |
Thermal | Mainly imaging | Passive | Emission | NA | 8–15 µm |
Chlorophyll fluorescence (kinetics) | Imaging/non-imaging | Active | Emission | 400–700 nm | ~ 650–800 nm |
Fluorescence | Imaging/non-imaging | Active | Emission | Mostly 300–400 nm | Mainly 400–700 nm |
Raman spectroscopy | Non-imaging | Active | Inelastic scattering of photons (Raman scattering) | Variable, often 785–830 nm [17] | Raman bands, 400–2133 cm−1 [18] |
Optical coherence tomography | Imaging | Active | Reflectance of coherent light | 800–1000 nm or 1200–1400 nm | 800–1000 nm or 1200–1400 nm |
X-ray computed tomography | Imaging | Active | Attenuation, phase shift | ~ 0.01–0.1 nm | Visible light using scintillator |