After exposure of one-year old seedlings of Swietenia macrophylla to an overnight temperature (13 C, 19 C, 25 C, 31 C or 35 C), the leaf net photosynthetic rate (Pn) was researched through measuring photosynthetic lig...
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After exposure of one-year old seedlings of Swietenia macrophylla to an overnight temperature (13 C, 19 C, 25 C, 31 C or 35 C), the leaf net photosynthetic rate (Pn) was researched through measuring photosynthetic light-response curves at 360 mmolmol-1 CO2, and photosynthetic CO2-response curves at light-saturated intensity (1500 mmolm-2 s-1). The optimal temperature for photosynthesis measured at 360 mmol穖ol-1 CO2 was from 25 C to 31 C, but which was from 31C to 35 C at saturating CO2 concentration. At temperature of below 25 C, the decline in Pn was mainly due to the drop in carboxylation efficiency (Ce), while as temperature was over 31 C, the reduction in Pn resulted from both decrease in Ce and increase in leaf respiration. The CO2-induced stimulation of photosynthesis was strongly inhibited at temperatures below 13 C. The results showed that, the leaf photosynthesis of tropical evergreen plants should not be accelerated at low temperature in winter season with elevated CO2 concentration in the future.
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