PDF(Pubmed)
Abstract：
Continuous light (CL) is available throughout the polar day for plants in the Arctic during the growing season, whereas provenances of the same species experience a very different environment with non-CL (NCL) just a few latitudes to the south. Both provenances need to acclimate to climate warming, yet we lack comprehensive understanding of how their growth, photosynthesis and leaf traits differ. Further, the provenances presumably have morphological and physiological adaptations to their native environments and therefore differ in response to photoperiod. We tested the height growth, leaf longevity, biomass accumulation, biomass allocation and rates of gas exchange of northern (67°N) and southern (61°N) Finnish silver birch (Betula pendula Roth) origins in CL- and NCL-treatments in a 4-month chamber experiment. Irrespective of photoperiod, 67°N had higher area-based photosynthetic rate (Anet), stomatal conductance (gs) and relative height growth rate (RGR), but lower stomatal density and fewer branches and leaves than 61°N. Photoperiod affected height growth cessation, biomass and photosynthetic traits, whereas leaf longevity and many leaf functional traits remained unchanged. In CL, both provenances had lower gs, higher RGR, increased shoot:root ratio and increased sink sizes (more branching, more leaves, increased total plant dry weight) compared with NCL. In NCL, 67°N ceased height growth earlier than in CL, which altered biomass accumulation and distribution patterns. Northern conditions impose challenges for plant growth and physiology. Whether a provenance inhabits and is adapted to an area with or without CL can also affect its response to the changing climate. Northern birches may have adapted to CL and the short growing season with a \'polar day syndrome\' of traits, including relatively high gas exchange rates with low leaf biomass and growth traits that are mainly limited by the environment and the earlier growth cessation (to avoid frost damage).
摘要：
在生长季节期间，北极的植物在整个极地日都可以使用连续光（CL），而同一物种的种源在南部只有几个纬度的非CL（NCL）的情况下经历了非常不同的环境。两种来源都需要适应气候变暖，然而我们对他们的成长缺乏全面的了解，光合作用和叶片性状不同。Further,种源可能对其天然环境具有形态和生理适应性，因此对光周期的反应不同。我们测试了身高增长，叶子长寿，生物量积累，在为期4个月的室内实验中，北部（67°N）和南部（61°N）芬兰白桦树（BetulapendulaRoth）起源于CL和NCL处理的生物量分配和气体交换速率。不考虑光周期，67°N具有较高的基于面积的光合速率（Anet），气孔导度(gs)和相对高度生长速率(RGR)，但气孔密度比61°N低，枝叶少。光周期影响身高生长停止，生物量和光合性状，而叶片寿命和许多叶片功能性状保持不变。在CL中，两个出处都有较低的GS，更高的RGR，增加的芽：根比例和增加的水槽大小(更多的分支，更多的叶子,与NCL相比，植物总干重增加）。在NCL中,67°N比CL更早地停止了高度增长，改变了生物量的积累和分布模式。北方条件对植物生长和生理学提出了挑战。出处是否居住并适应有或没有CL的地区也会影响其对气候变化的反应。北方桦树可能已经适应了CL和短的生长季节，具有“极日综合症”的特征，包括相对较高的气体交换率和较低的叶片生物量和生长特性，这些特性主要受环境和较早的生长停止（以避免霜冻损害）的限制。
