レーザ誘起蛍光法による植物の生育状態のモニタリングに関する基礎的研究 (第2報)

Abstract

The fluorescence spectra of intact leaves illuminated with laser light (Ar+laser 488 nm) shows two peaks around 685 nm (Hip) and 740 nm (FIp). The intensity ratio of the FIp peak to the Fllp peak (FIp/FIIp ratio) is linearly elevated with increasing chlorophyll content. In this investigation, in order to examine the effect of temperatures from 5 °C to 60 °C on chlorophyll fluorescence spectra and on the measurement of chlorophyll content, chlorophyll fluorescence spectra of wild type (nourin-8) and chlorina mutant (MGS 88) rice leaves were measured. The spectra were analyzed by resolving them into Gaussian curve components using five tentative fluorescence emitter components (F680, F685, F695, F720 and F740) based on the model proposed by Wittmershaus et al., and one minor emitter component (F780) at a longer wavelength.The peak ratio and emitter area ratios of laser-induced fluorescence spectra of the nourin 8 leaves indicated constant value within a temperature range from 20 °C to 40 °C. Values changed at low temperatures (below 20 °C) and at high temperatures (above 40 °C). The method of measuring chlorophyll content by using peak ratio and emitter area ratios of LIF spectra was useful in practical application in the optimum temperature range (20 °C to 40 °C) for growing rice. Resolution analysis of fluorescence spectra showed changes in fluorescence spectra induced by temperature and chlorophyll contents were affected by the emitters (F680, F685 and F740) relating to lightharvesting chlorophyll.We conclude that the LIF method is useful for monitoring the effect of temperature of light-harvesting chlorophyll and the chlorophyll content in rice plant leaves of normal temperature conditions in the plant factory.