A study on the spectral change in a chlorophyll absorption band monitored during the growth of japanese tea leaves

Daitaro Ishikawa, Yukihiro Ozaki, Gerrit Hoogenboom, Etsuji Ishiguro

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

In this study, the visible spectra and Chlorophyll (Chl) bands of tea leaves were investigated by using a handheld spectrometer during their growing period. The original absorbance spectra and their second derivative spectra in the 400-1100 nm were obtained, and bands at around 485, 558 and 680 nm were assigned to Chl absorption. Because the absorption around 485 nm is sensitive to the instrument's detector, and the 558 nm is weaker than the 680 nm band, the absorption band at around 680 nm was used for our detailed analysis. It was found that the growing stage of Japanese tea can be separated into three stages, the first, second, and final stage based on day of year (DOY): 74-91, 91-112, and 112-116, respectively, by the inflection point's changing of the band around 680 nm. That inflection points were located at different positions for the first and final stages. This result suggests that the old and new leaves have a peak at different wavelengths. On the other hand, the band linearly shifted to a shorter wavelength between DOY: 91-105 (second stage). However, with respect to combination of the old and new leaves in the simulation, it was confirmed by the ratio of old and new leaves in the field of view (FOV) that this type of the behavior may occur during this period. The intensity change in the band was also separated into three stages; in the second stage, especially, the intensity of the band also increased linearly. It is very likely that the intensity change in the second stage depends mainly on the growth of new leaves. Therefore, the results obtained suggest that it is possible to evaluate the growth of tea leaves by using the band around 680 nm because of the function of Chl.

Original languageEnglish
Pages (from-to)255-263
Number of pages9
JournalJournal of Agricultural Meteorology
Volume69
Issue number4
DOIs
Publication statusPublished - 2013 Sep 1

Keywords

  • Chlorophyll
  • Gaussian fitting
  • Optimal harvest period
  • Second derivative
  • Visible spectroscopy

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Atmospheric Science

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