The advantages of using green light to follow fluorescence changes – Photosynthesis – Application Note 1

Introduction

This application note aims to show how a JTS-10 can be used to follow fluorescence changes in a leaf, to study in-vivo photosynthetic processes. Experiments described here are based on a work realised by F. Rappaport et al (1). Fluorescence phenomenon reflects the electron transport process and is controlled by the redox states of electron acceptor or electron donor of photosystem II.
The measurement of chlorophyll fluorescence kinetics has been widely investigated, using red lights at 635 nm or blue lights at 470 nm, in leaves, since these wavelengths are strongly absorbed by chlorophylls. Commonly, fluorescence is studied via a modulated light beam. Two lights are used: an exciting light and a probing light modulated. This method has the strong drawback of limiting the time resolution of the technique to the frequency of the modulated source. An innovative idea was to use a green light (520 nm) to induce fluorescence. The exciting and the detecting lights are supplied by the same light source: a LED board : Fluo_59 specialy designed with green LEDs. F. Rappaport et al. (1), proved that fluorescence emitted by the leaf under a strong absorbed beam by chlorophyll was lower than using a weaker absorbed beam such as green light. The light intensity at 520 nm is expected higher throughout the leaf.

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