962 
Japan). Ozone was generated by electric discharging and 
analyzed by another gas tester system (GASTEC Co. 
18L, Kanagawa, Japan). Chlorophyll contents were 
measured by the method of Amon (1949). Some of the 
rice leaves were preillummated by halogen light passed 
through interference filters of 660 nm (17.5 W m' 2 ) and 
700 nm (21.5 W m' 2 ) (Nippon Shinkuu Kogaku, Tokyo, 
Japan), and by Ar (477 & 488 nm, 280 W m' 2 , NEC 
GLG3028, Kawasaki, Japan) and He-Ne (633 nm, 450 
W m" 2 , NEC GLG5360, Kawasaki, Japan) laser lights 
while others were adapted to darkness. 
Spectra of chlorophyll fluorescence were measured 
by a multichannel spectrometer (Takahashi et al., 1991). 
A leaf segment was fixed on a sample holder of the 
apparatus, and projected by Ar (477 & 488 nm, 280 
W m~ 2 ) and diode (693 nm, 110 W m~ 2 , Applied Opt- 
P burnin g Inc. STK-DP694-16G-155, Saitama, Japan) 
laser lights. Induced fluorescences were introduced to 
the spectrometer by an optical fiber and fluorescence 
spectra were measured by a diode-array detector 
Li I I _i J 1— 
650 680 710 740 770 800 
WAVELENGTH (nm) 
Fig. 1 Spectral changes of chlorophyll fluorescence in 
an intact leaf of rice wild-type plant with temperatures, 
(a) 25°C, (b) 45°C and (c) 60°C. Fluorescences were 
induced by the Ar laser light (477 & 488 nm) and spectra 
were resolved into 5 main emitter components (F680, 
F685, F695, F725 and F745) and one or two minor 
components at the longer side. Chlorophyll content of 
the leaf was 54.0 nmol cm" 2 . 
equipped with an image intensifier (512 sampling points, 
Tracor Northern TN6133, Wisconsin, U.SA.). Spectra 
were measured at times when induced fluorescence 
reached the maximum, approximately 1 s after initiation 
of laser light projections. Measurements were carried 
out at 25°C except for the experiments for effects of 
temperature. Spectral data were transferred to a 
multipurpose data processing system (Seki Technotron 
SK-296, Tokyo, Japan) and subjected to correction of 
sensitivity of the detector for wavelengths. Then spectra 
were resolved into tentative fluorescence emitter 
components of Gaussian peaks by curve fitting with a 
micro-computer (NEC PC-980IRA, Kawasaki, Japan) 
(Takahashi et al., 1991). 
3. RESULTS 
Effects of temperature on chlorophyll fluorescence 
were examined. The fluorescence spectrum of a rice leaf 
containing 54.0 nmol cm ' 2 chlorophylls showed two 
peaks around 685 nm (Fn) and 740 nm (Fj) (Fig. la) as 
reported for other intact leaves (Kocsanyi et al., 1988; 
Rinderie & Lichtenthaler, 1988; Takahashi et al., 1991) 
The Fn peak decreased against the Fi peak by raising 
temperature up to 45°C (Fig. lb). The spectral shape 
remarkably changed when the temperature was raised to 
60°C (Fig. lc); a bend between the peaks grew shallow. 
In order to analyze the change, the spectra were resolved 
into 5 main tentative emitter components, F680, F 68 S, 
F695, F725 and F745, and other one or two emitters 
at longer wavelengths (F770 - F790). Changes in 
proportions of emitters by raising temperature are shown 
in Fig. 2. Proportion of F685 began to decrease al 40°C, 
F680 at 45°C and F745 at 50°C, while those of F695 and 
F725 increased above 50°C 
Similar spectral changes of chlorophyll fluorescence 
to those induced by high temperature were observed 
when kidney bean leaves were fumigated with air- 
Fig. 2 Changes of proportions of the emitters in 
chlorophyll fluorescence with temperatures. The data 
used were the same as Fig. 1. Symbols indicate • F680, 
O F685, □ F695, OF725 and A F745.