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Deriving Nitrogen Indicators of Maize Using the Canopy Chlorophyll Content Index

¹Y. Miao, ²F. Li

1. China Agricultural University, Beijing, China
2. Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China

Many spectral indices have been proposed to derive aerial nitrogen (N) status parameters of crops in recent decades. However, most of red light based spectral indices easily loss sensitivity at moderate-high aboveground biomass. The objective of present study is to assess the performance of red edge based Chlorophyll Canopy Content Index (CCCI) in deriving N concentration and aerial N uptake of maize (Zea mays L.). The CCCI was developed based on a two dimensional method with the use of the normalized difference vegetation index (NDVI) accounting for variation in canopy coverage, and the normalized difference red edge (NDRE) accounting for measuring of crop N. Experiments including different N rates in maize were conducted in 2009 and 2010 in Quzhou County of the North China Plain. The spectral indices were derived from simulated GreenSeeker and Crop Circle active crop canopy sensor bands. The results indicated that growth stages had a significantly influences on the relationships between spectral indices and aerial N related indicators. The two-dimensional CCCI were found to be more stable and better predictors than traditional red light based NDVI and RVI in estimating aerial N concentration and the aerial N uptake. For aerial N concentration, values of coefficient of correlation (r) ranged from 0.54 to 0.82. For aerial N uptake, r values ranged from 0.75 to 0.84. The relationship between CCCI and aerial N concentration was better under full maize cover conditions. We concluded that CCCI using the planar domain index approach significantly improved the prediction power of red edge dependent vegetation indices in deriving the aerial N status. The findings from this study are potentially useful to manage N fertilizer application in maize.

Keyword: CCCI; Nitrogen status; Red edge.

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