Zaragoza-Castells Joana, Sánchez-Gómez David, Valladares Fernando, Hurry Vaughan, Atkin Owen K
Department of Biology, University of York, York, YO10 5YW, UK.
Plant Cell Environ. 2007 Jul;30(7):820-33. doi: 10.1111/j.1365-3040.2007.01672.x.
Understanding the response of leaf respiration (R) to changes in irradiance and temperature is a prerequisite for predicting the impacts of climate change on plant function and future atmospheric CO2 concentrations. Little is known, however, about the interactive effects of irradiance and temperature on leaf R. We investigated whether growth irradiance affects the temperature response of leaf R in darkness (Rdark) and in light (Rlight) in seedlings of a broad-leaved evergreen species, Quercus ilex. Two hypotheses concerning Rdark were tested: (1) the Q10 (i.e. the proportional increase in R per 10 degrees C rise in temperature) of leaf Rdark is lower in shaded plants than in high-light-grown plants, and (2) shade-grown plants exhibit a lower degree of thermal acclimation of Rdark than plants exposed to higher growth irradiance. We also assessed whether light inhibition of Rlight differs between leaves exposed to contrasting temperatures and growth irradiances, and whether the degree of thermal acclimation of Rlight is dependent on growth irradiance. We showed that while growth irradiance did impact on photosynthesis, it had no effect on the Q10 of leaf Rdark. Growth irradiance had little impact on thermal acclimation when fully expanded, pre-existing leaves were exposed to contrasting temperatures for several weeks. When Rlight was measured at a common irradiance, Rlight/Rdark ratios were higher in shaded plants due to homeostasis of Rlight between growth irradiance treatments and to the lower Rdark in shaded leaves. We also showed that Rlight does not acclimate to the same degree as Rdark, and that Rlight/Rdark decreases with increasing measuring and growth temperatures, irrespective of the growth irradiance. Collectively, we raised the possibility that predictive carbon cycle models can assume that growth irradiance and photosynthesis do not affect the temperature sensitivity of leaf Rdark of long-lived evergreen leaves, thus simplifying incorporation of leaf R into such models.
了解叶片呼吸作用（R）对光照强度和温度变化的响应是预测气候变化对植物功能及未来大气二氧化碳浓度影响的前提条件。然而，关于光照强度和温度对叶片R的交互作用却知之甚少。我们研究了生长光照强度是否会影响阔叶常绿树种冬青栎幼苗在黑暗（Rdark）和光照（Rlight）条件下叶片R的温度响应。针对Rdark检验了两个假设：（1）遮荫植物叶片Rdark的Q10（即温度每升高10℃时R的比例增加）低于高光生长的植物；（2）遮荫生长的植物叶片Rdark的热驯化程度低于接受较高生长光照强度的植物。我们还评估了在不同温度和生长光照强度下，光照对Rlight的抑制作用是否存在差异，以及Rlight的热驯化程度是否依赖于生长光照强度。我们发现，虽然生长光照强度确实会影响光合作用，但对叶片Rdark的Q10没有影响。当充分展开的、已存在的叶片在不同温度下暴露数周时，生长光照强度对热驯化影响很小。当在相同光照强度下测量Rlight时，由于生长光照强度处理间Rlight的稳态以及遮荫叶片中较低Rdark，遮荫植物的Rlight/Rdark比值更高。我们还表明，Rlight的驯化程度与Rdark不同，并且Rlight/Rdark会随着测量温度和生长温度的升高而降低，与生长光照强度无关。总体而言，我们提出了一种可能性，即预测性碳循环模型可以假定生长光照强度和光合作用不会影响长寿常绿叶片叶片Rdark的温度敏感性，从而简化将叶片R纳入此类模型的过程。
