Non-destructive evaluation of chlorophyll content in tea leaves using hyperspectral reflectance from a compact spectrometer

Abstract

Chlorophyll content has been used as an indicator for assessing photosynthetic ability, health and defense against a variety of degenerative diseases. Hyperspectral remote sensing offers some non-destructive methods and has played an important role in evaluating vegetation characteristics. However, the prices of traditional field portable spectroradiometers, such as Ocean Optics Hyperspectral Vis-NIR spectroradiometers and Analytical Spectral Devices FieldSpec series, have not yet decreased to consumer levels, which prevents much practical use. Recently, fingertip-sized spectrometers have been developed and then they could be powerful tools for evaluating vegetation characteristics. In the present study, a compact spectrometer (C12880MA-10, Hamamatsu Photonics) was used to evaluate chlorophyll content in tea leaves. Incorporating pre-processing techniques was effective for obtaining estimated values with high accuracy and then de-trending was the best pre-processing technique in this study, achieving an RPD of 2.03 and an RMSE of 3.07 μg cm^－2. The proposed method is cost effective, practical for consumers to apply and will enable effective crop management.