Spectral line

Reflection (computer programming)

Chlorophyll

Biology

Mineralogy

Computer science

Botany

Chlorophyll a

Geology

Chlorophyll fluorescence

Content (measure theory)

Physics

Organic chemistry

Plant species

Mathematics

Spectral index

Optics

Astronomy

Pigment

Spectral properties

Photochemical Reflectance Index

Environmental science

Mathematical analysis

Computational chemistry

Remote sensing

Chemistry

Programming language

Biological system

Reflectivity

Plant Cell & Environment

Chlorophyll is one of the primary pigments of plant leaves, and changes in its content can be used to characterize the physiological status of plants. Spectral indices have been devised and validated for estimating leaf chlorophyll content (LCC). However, most of the existing spectral indices do not consider the influence of angular reflection on the accuracy of the LCC estimation. In this study, the spectral reflectance factors of leaves from three plant species were measured from several observations in the principal plane. The relationship between the existing spectral indices and the LCC from different directions suggests that the directional reflection of a leaf surface impacts the accuracy of its LCC estimation. Subsequently, the ratio of reflectance differences, that is, the modified Datt index, was tested to reduce the directional reflection effect when predicting LCC. Our results indicated that the modified Datt index not only estimated LCC with high accuracy for all observation directions and plant species but also consistently predicted the LCC of each species in individual observation directions. Our method opens the possibility for optical detection of LCC using multiangular spectral reflection, which is convenient for plant science studies focused on the variation in LCC.

Estimation of the leaf chlorophyll content using multiangular spectral reflectance factor