公告日期 : 2017-03-01
The Influence of Temperature on the Photochemical Efficiency of Photosystem ΙΙ in Podocarpaceae Seedlings from Different Regions
Authors：Ming-Nan Chen, Tien-Szu Liao
Key words：Podocarpaceae, chlorophyll fluorescence, photochemical efficiency, temperature, distribution
Podocarpus nakaii, P. fasciculus, P. costalis, and P. macrophyllus are 4 Podocarpaceae species
with functional broad leaves, distributed at different elevations and regions. They were placed on 3
sites at different elevations with shade acclimation for 1 yr to detect photosystem II photochemical
efficiency differences due to a temperature gradient. Results showed that the predawn maximum
quantum yield of PSII (Fv/Fm) was closely related to the early morning minimum temperature.
The decrease in PSII (Fv/Fm) at noon was closely related to the accumulated temperature in the
morning. PSII (Fv/Fm) of P. nakaii, a low-elevation species, was sensitive to temperature, and
gradually showed an effect below 10℃. However, it might use non-photochemical dissipation to
survive low temperatures in winter. PSII (Fv/Fm) of P. costalis, a tropical low-elevation species,
could adapt to lower temperatures than that of P. nakaii, but showed severe decay near freezing
temperatures. This suggests that PSII (Fv/Fm) was not sensitive to temperature, but could not
resist freezing temperatures. PSII (Fv/Fm) of P. fasciculus, a high-elevation species, and P.
macrophyllus,a widely distributed species, could adapt to a wide temperature range. PSII photochemical
efficiency was still retained near freezing temperatures, and excess energy might be dissipated via
non-photochemical dissipation, making them able to adapt to the understory at higher elevations or
latitudes in winter. PSII photochemical performance characteristics and geographical distribution
of the 4 seedlings were compared.