Department of Crop Production Ecology, Swedish University of Agricultural Sciences (SLU), Uppsala, 750 07, Sweden.
Department of Biology, University of Western Ontario, London, N6A 5B7, Ontario, Canada.
Plant Cell Environ. 2019 Jun;42(6):1913-1928. doi: 10.1111/pce.13525. Epub 2019 Mar 22.
Under future climates, leaf temperature (T ) will be higher and more variable. This will affect plant carbon (C) balance because photosynthesis and respiration both respond to short-term (subdaily) fluctuations in T and acclimate in the longer term (days to months). This study asks the question: To what extent can the potential and speed of photosynthetic acclimation buffer leaf C gain from rising and increasing variable T ? We quantified how increases in the mean and variability of growth temperature affect leaf performance (mean net CO assimilation rates, A ; its variability; and time under near-optimal photosynthetic conditions), as mediated by thermal acclimation. To this aim, the probability distribution of A was obtained by combining a probabilistic description of short- and long-term changes in T with data on A responses to these changes, encompassing 75 genera and 111 species, including both C3 and C4 species. Our results show that (a) expected increases in T variability will decrease mean A and increase its variability, whereas the effects of higher mean T depend on species and initial T , and (b) acclimation reduces the effects of leaf warming, maintaining A at >80% of its maximum under most thermal regimes.
在未来的气候条件下，叶片温度（T）将会更高且更具波动性。这将影响植物的碳（C）平衡，因为光合作用和呼吸作用都会对 T 的短期（亚日）波动做出响应，并在更长的时间（几天到几个月）内适应。本研究提出了一个问题：光合作用的适应潜力和速度在多大程度上可以缓冲因叶片 T 升高和增加的波动性而导致的 C 增益？我们量化了生长温度均值和变异性的增加如何通过热适应来影响叶片性能（平均净 CO 同化率 A；其变异性；以及在接近最佳光合作用条件下的时间）。为此，我们将 T 的短期和长期变化的概率描述与 A 对这些变化的响应数据相结合，获得了 A 的概率分布，涵盖了 75 个属和 111 个种，包括 C3 和 C4 物种。我们的结果表明：（a）T 变异性的预期增加将降低平均 A 值并增加其变异性，而较高的平均 T 的影响取决于物种和初始 T；（b）适应可以减少叶片变暖的影响，在大多数热环境下将 A 维持在其最大值的 80%以上。
