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Physiological basis of seasonal trend in leaf photosynthesis of five evergreen broad-leaved species in a temperate deciduous forest

Miyazawa, Y., Kikuzawa, K.
Tree physiology 2006 v.26 no.2 pp. 249-256
Camellia japonica, Cleyera japonica, Photinia, Castanopsis cuspidata, Quercus glauca, forest trees, leaves, nitrogen content, photosynthesis, net assimilation rate, temperature, electron transfer, light intensity, carboxylation, ribulose-bisphosphate carboxylase, enzyme activity, temperate forests, deciduous forests, mathematical models, equations, Japan
The physiological basis of photosynthesis during winter was investigated in saplings of five evergreen broad-leaved species (Camellia japonica L., Cleyera japonica Thunb., Photinia glabra (Thunb.) Maxim., Castanopsis cuspidata (Thunb.) Schottky and Quercus glauca Thunb.) co-occurring under deciduous canopy trees in a temperate forest. We focused on temperature dependence of photosynthetic rate and capacity as important physiological parameters that determine light-saturated rates of net photosynthesis at low temperatures during winter. Under controlled temperature conditions, maximum rates of ribulose bisphosphate carboxylation and electron transport (V(cmax) and J(max), respectively) increased exponentially with increasing leaf temperature. The temperature dependence of photosynthetic rate did not differ among species. In the field, photosynthetic capacity, determined as V(cmax) and J(max) at a common temperature of 25 degrees C (V(25)cmax and J(25)max), increased until autumn and then decreased in species-specific patterns. Values of V(25)cmax and J(25)max differed among species during winter. There was a positive correlation of V(25)cmax with area-based nitrogen concentration among leaves during winter in Camellia and Photinia. Interspecific differences in V(25)cmax were responsible for interspecific differences in light-saturated rates of net photosynthesis during winter.