In response to global warming, trees are expected to shift their distribution ranges to higher latitudes. The range shift will expose them to novel environmental conditions, such as new photoperiod regimes. These factors can interact with rising atmospheric CO2 ([CO2 ]) to affect trees' physiology and growth. This study simulated future environmental conditions to investigate photosynthetic responses to changes in photoperiod regimes (seed origin (48°N), 52, 55, and 58°N) and [CO2 ] (ambient 400 vs. elevated 1000 μmol mol-1 ) in white birch (Betula papyrifera Marsh) seedlings. Our results show that elevated [CO2 ] stimulated leaf photosynthesis (Pn ) at the two lower latitudes (48 and 52°N). However, this stimulation by elevated [CO2 ] was lost in the two higher latitudes (55 and 58°N). Elevated [CO2 ] led to the down-regulation of maximum Rubisco activity (Vcmax ) for the two higher latitudes, and maximum electron transport rate (Jmax ) and triose phosphate utilization (TPU) at 58° N, while it enhanced Jmax and TPU for the two lower latitudes. Increased instantaneous water-use efficiency (IWUE) for the two lower latitudes was primarily attributed to the CO2 stimulation of Pn while the higher IWUE under the photoperiod regimes of 55 and 58°N latitudes was explained by reduced water loss. Photoperiod effects varied with [CO2 ]: Pn increased at the photoperiod regimes of 55 and 58°N in ambient [CO2 ] while it tended to decline under these photoperiods in elevated [CO2 ]. Our study suggests that the photosynthesis of white birch will likely respond negatively to northward migration or seed transfer in response to climate change. This article is protected by copyright. All rights reserved.

中文翻译：

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较长的光周期抵消了 Betula papyrifera Marsh 光合作用的 CO 2 刺激：对气候变化引起的迁移的影响

为应对全球变暖，预计树木会将其分布范围转移到更高的纬度。范围转移将使它们暴露在新的环境条件下，例如新的光周期制度。这些因素可以与上升的大气 CO2 ([CO2 ]) 相互作用，从而影响树木的生理和生长。本研究模拟了未来的环境条件，以研究对光周期变化（种子起源 (48°N)、52、55 和 58°N）和 [CO2 ]（环境 400 与升高的 1000 μmol mol-1）变化的光合响应白桦（Betula papyrifera Marsh）幼苗。我们的结果表明，升高的 [CO2] 刺激了两个低纬度地区（48 度和 52 度）的叶片光合作用 (Pn)。然而，这种由升高的 [CO2] 引起的刺激在两个高纬度地区（北纬 55 度和 58 度）消失了。升高的 [CO2 ] 导致两个高纬度地区的最大 Rubisco 活性 (Vcmax ) 以及最大电子传输速率 (Jmax ) 和磷酸丙糖利用率 (TPU) 在 58° N 的下调，同时它增强了 Jmax 和 TPU两个较低的纬度。两个低纬度地区瞬时用水效率 (IWUE) 的增加主要归因于 Pn 的 CO2 刺激，而在 55°N 和 58°N 纬度的光周期条件下，IWUE 较高的原因是水分损失减少。光周期效应随 [CO2 ] 变化：在环境 [CO2 ] 中，Pn 在 55°N 和 58°N 的光周期范围内增加，而在 [CO2 ] 升高的这些光周期下，Pn 趋于下降。我们的研究表明，白桦的光合作用可能会对北移或种子转移产生负面反应，以应对气候变化。本文受版权保护。版权所有。