Allen M T, Pearcy R W
Section of Evolution and Ecology, University of California, Davis, CA 95616, USA e-mail:
Oecologia. 2000 Mar;122(4):479-486. doi: 10.1007/s004420050969.
Photosynthetic performance under dynamic light regimes was assessed in four different species of tropical shrubs from the family Rubiaceae via field gas exchange measurements conducted on Barro Colorado Island, Panamá. Rates of photosynthetic induction and induction loss were assessed throughout the day in both the wet and dry seasons in order to determine the relative roles of stomata and biochemistry in limiting photosynthetic performance under transient light conditions. A high degree of coordination was observed between stomatal conductance and biochemical capacity for CO assimilation during induction. Rates of biochemical and overall photosynthetic induction sharply decreased when initial stomatal conductance fell below a narrow range of critical values. Time of day or season did not affect rates of biochemical deactivation upon shading, but did influence stomatal closure, which often exerted a significant influence over induction loss in the darkness. In measurements of total assimilation due to a 60-s light pulse, both biochemical activity and stomatal conductance were linearly related to total CO uptake. Only during the mornings of the wet season was stomatal conductance consistently high enough to be non-limiting to dynamic photosynthetic performance. At all other times, stomatal behavior exercised significant influence over induction times, photosynthetic induction loss, and total CO uptake from 60-s light pulses.
通过在巴拿马巴罗科罗拉多岛进行的田间气体交换测量，评估了茜草科四种不同热带灌木在动态光照条件下的光合性能。在雨季和旱季全天评估光合诱导率和诱导损失率，以确定气孔和生化过程在瞬时光照条件下限制光合性能方面的相对作用。在诱导过程中，观察到气孔导度和CO同化生化能力之间存在高度协调性。当初始气孔导度降至狭窄的临界值范围以下时，生化和总体光合诱导率急剧下降。一天中的时间或季节不影响遮光后生化失活的速率，但会影响气孔关闭，而气孔关闭通常对黑暗中的诱导损失有显著影响。在60秒光脉冲引起的总同化测量中，生化活性和气孔导度均与总CO吸收呈线性相关。只有在雨季的早晨，气孔导度始终足够高，不会限制动态光合性能。在所有其他时间，气孔行为对诱导时间、光合诱导损失以及60秒光脉冲的总CO吸收有显著影响。
