. 2018 Jul 3;9:936. doi: 10.3389/fpls.2018.00936

Table 4.

Simple linear relationship between PNC and vegetation indices (R²).

VI	Pre-heading	Post-heading	Entire season
NDVI_a	0.52^***	0.02^ns	0.02^ns
CI_G−a	0.70^***	0.04^*	0.02^ns
CI_RE−a	0.70^***	0.28^***	0.14^***
OSAVI_a	0.56^***	0.28^***	0.05^**
VI_opt−a	0.64^***	0.28^***	0.05^**
NDVI_g	0.43^***	0.35^***	0.10^***
CI_G−g	0.61^***	0.27^***	0.20^***
CI_RE−g	0.63^***	0.40^***	0.26^***
OSAVI_g	0.48^***	0.47^***	0.14^***
VI_opt−g	0.54^***	0.46^***	0.17^***
NDI_opt−g	0.01^ns	0.00^ns	0.28^***
MTCI_g	0.63^***	0.35^***	0.32^***
PRI_g	0.51^***	0.48^***	0.65^***
BNI_g	0.64^***	0.39^***	0.68^***

VI_a and VI_g denote VI from aerial and ground-based platform, respectively. The numbers in bold denotes the maximum in each column. Significance level: ns, not significant,

p < 0.05,

^**

p < 0.01,

^***

p < 0.001.

NDVI, Normalized difference vegetation index; CI_G, Green chlorophyll index; CI_RE, Red edge chlorophyll index; OSAVI, Optimized soil adjusted vegetation index; VI_opt, Optimal vegetation index; NDI_opt, Optimal normalized difference index; MTCI, MERIS terrestrial chlorophyll index; PRI, Photochemical reflectance index; BNI, Blue nitrogen index.