Roberntz P
Department for Production Ecology, Swedish University of Agricultural Sciences, P.O. Box 7042, SE-750 07 Uppsala, Sweden.
Tree Physiol. 2001 Aug;21(12-13):931-40. doi: 10.1093/treephys/21.12-13.931.
Branches of field-grown Norway spruce (Picea abies (L.) Karst.) trees were exposed to either long-term ambient or to elevated CO2 concentrations ([CO2]) using the branch bag technique. The light-saturated photosynthetic rates (A(max)) of current-year shoots differing in nitrogen (N) status were measured at various temperatures and at either ambient (360 micromol mol(-1), AMB) or elevated (ambient + 350 micromol mol(-1), EL) [CO2]. The value of A(max) was determined at various intercellular [CO2]s (A/Ci curves) and used to normalize photosynthetic rates to the mean treatment C(i) values, which were 200 micromol mol(-1) (AMB) and 450 micromol mol(-1) (EL), respectively. Needle N status and temperature strongly affected A(max). The response to N increased with temperature, and the photosynthetic temperature optimum increased with N status. This was assumed to be a result of reduced mesophyll CO2 conductance. The relative increase of Amax in the EL treatment compared to the AMB treatment varied from 15 to 90%, and increased with temperature, but decreased with N status. Nevertheless, the absolute photosynthetic response to EL increased with shoot N status. The relative increase in the instantaneous response of A(max) to elevated [CO2] was about 20% higher than the long-term response, i.e., there was downward acclimation in Amax in response to elevated [CO2]. The photosynthetic temperature optimum increased 4 degrees C with either a short- or a long-term increase in [CO2]. The bag treatment itself increased A(max) by approximately 16% and the temperature optimum of A(max) by approximately 3 degrees C.
利用分支袋技术，将田间种植的挪威云杉（Picea abies (L.) Karst.）树的树枝暴露于长期环境二氧化碳浓度或升高的二氧化碳浓度（[CO₂]）下。在不同温度以及环境（360 μmol mol⁻¹，AMB）或升高（环境浓度 + 350 μmol mol⁻¹，EL）[CO₂]条件下，测定了氮（N）状态不同的当年生嫩枝的光饱和光合速率（A(max)）。在不同细胞间[CO₂]浓度下（A/Ci曲线）测定A(max)的值，并用于将光合速率标准化为平均处理C(i)值，分别为200 μmol mol⁻¹（AMB）和450 μmol mol⁻¹（EL）。针叶N状态和温度强烈影响A(max)。对N的响应随温度升高而增加，光合温度最适值随N状态升高而增加。这被认为是叶肉CO₂传导率降低的结果。与AMB处理相比，EL处理中A(max)的相对增加幅度在15%至90%之间，且随温度升高而增加，但随N状态降低。然而，对EL的绝对光合响应随嫩枝N状态增加。A(max)对升高的[CO₂]的瞬时响应的相对增加比长期响应高约20%，即A(max)对升高的[CO₂]存在向下适应性变化。随着[CO₂]短期或长期增加，光合温度最适值升高4℃。袋处理本身使A(max)增加约16%，A(max)的温度最适值增加约3℃。
