© 2006 Heron Publishing—Victoria, Canada
Seasonal variation in photosystem II efficiency and photochemical reflectance index of evergreen trees and perennial grasses
growing at low and high elevations in subtropical Taiwan
Jen-Hsien Weng (1, 3), Tien-Szu Liao (2), Mon-Yuan Hwang (1), Chi-Ch Chung (1), Chung-Ping Lin (1) and Chung-Hei Chu (1)
1. Department of Life Sciences, National Chung-Hsing University, Taichung, Taiwan / 2. Department of Forestry, National Chung-Hsing University, Taichung, Taiwan / 3. Corresponding author (jhweng@dragon.nchu.edu.tw) / Received July 4, 2005; accepted November 20, 2005; published online May 1, 2006
Summary
Three pines species, three evergreen broadleaf trees, one C3 and two C4 perennial grasses of subtropical Taiwan were studied to elucidate the correlation between photosystem II (PSII) efficiency
and photochemical reflectance index (PRI = (R531 – R570)/(R531 + R570)). Measurements were made at two sites differing in altitude (800 and 2600 m) over several growing seasons. At high elevation,
potential PSII efficiency, measured by chlorophyll fluorescence (the ratio of variable to maximal fluorescence; Fv/Fm) at predawn, decreased with decreasing air temperature and varied greatly among species. At the lowest air temperature (–3
°C) studied, variation in Fv/Fm among species ranged from 0.33 to 0.72. In contrast, at low elevation where air temperature was moderate, seasonal variation
in Fv/Fm was small in all of the study species. When species, elevation and season data were pooled, despite the high variation in
Fv/Fm among species, a good correlation between Fv/Fm and PRI was observed. When compared at the same value of PRI, Fv/Fm of evergreen trees was higher than that of perennial grasses; however, when the minimum temperature on the measurement day
was below 0 °C, Fv/Fm was underestimated relative to PRI. We conclude that PRI could be used as a remote indicator of photosynthetic function when
air temperature is above 0 °C.
Keywords:
altitude, chlorophyll fluorescence, leaf spectral reflectance, PRI, season, species, subtropical.
