Relationship between nitrogen and chlorophyll content and spectral properties in maize leaves

Abstract

The relationships between leaf nitrogen concentration, chlorophyll concentration, reflectance (R), absorptance (A) and transmittance (T) in a spectral band ranging from 400 to 1100 nm were studied on maize leaves growing at two different positions on the stem. Leaves were taken from field-grown plants fertilized with three levels of nitrogen at two different stages.Spectral R and T of leaves were determined in vivo using a hand-held spectroradiometer connected to an external integrating sphere. A was computed as : A = 100 - (R + T).Significant curvilinear relationships were observed between maize leaf spectral properties and leaf chlorophyll and nitrogen concentrations. According to the model utilized, of the type Y = W· [l ± B· e(-KX)], progressive increase in chlorophyll and/or nitrogen concentration led to progressive decrease in R and T and progressive increase in A.Variations in A and T were analogous in every spectral band within the PAR but the 520600 nm wave band showed a consistently higher variability and threshold value than the 450520 nm or 630-690 nm bands.The data show that the N and chlorophyll contents of field-grown maize leaves can be quickly estimated from measurements of A and T, but not of R, especially when the contents of these constituents are medium to high. The 520-600 nm wave band gave a better estimate of N and chlorophyll concentrations than the other two bands.