Table 4 Spectral vegetation indices used in this study to evaluate maize above ground biomass

CIgreen

\(\frac{NIR}{GREEN} - 1\)

Chlorophyll

[33]

CIrededge

\(\frac{NIR}{REDEDGE} - 1\)

Chlorophyll

[33]

CVI

\(NIR * \frac{RED}{{GREEN^{2} }}\)

Chlorophyll

[34]

NDRE

\(\frac{NIR - REDEDGE}{NIR + REDEDGE}\)

Chlorophyll

[35]

RVI

\(\frac{NIR}{RED}\)

LAI, biomass

[36,37,38]

NDVI

\(\frac{NIR - RED}{NIR + RED}\)

Biomass

[39, 40]

WDRVI

\(\frac{0.1NIR - RED}{0.1NIR + RED}\)

LAI, biomass

[41]

GLI

\(\frac{2 * GREEN - RED - BLUE}{2 * GREEN + RED + BLUE}\)

Chlorophyll

[42, 43]

VARI

\(\frac{GREEN - RED}{GREEN + RED - BLUE}\)

LAI, biomass

[44, 45]

ExG

\(2 * GREEN - RED - BLUE\)

Canopy coverage

[46]

NGRDI

\(\frac{GREEN - RED}{GREEN + RED}\)

Canopy coverage

[39]