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Predawn leaf conductance depends on previous day irradiance but is not related to growth in aspen saplings grown under artificially manipulated air humidity
Functional Plant Biology ( IF 2.6 ) Pub Date : 2020-12-08 , DOI: 10.1071/fp20254
Priit Kupper , Ants Kaasik , Mai Kukumägi , Gristin Rohula-Okunev , Linda Rusalepp , Anu Sõber

Recent studies have suggested that predawn stomatal opening may enhance early-morning photosynthesis (A) and improve the relative growth rate of trees. However, the causality between night-time stomatal conductance, A, and tree growth is disputable because stomatal opening in darkness can be mediated by previous day photosynthate loads and might be a consequence of growth-related processes like dark respiration (R). To identify linkages between night-time leaf conductance (gl_night), A, R, and tree growth, we conducted an experiment in hybrid aspen saplings grown under different air relative humidity (RH) conditions and previous day irradiance level (IR_pday). Predawn leaf conductance (gl_predawn) depended on RH, IR_pday and R (P < 0.05), whereas early-morning gross A (Agross_PAR500) depended on IR_pday and gl_predawn (P < 0.001). Daytime net A was positively related to Agross_PAR500 and leaf [N] (P < 0.05). Tree diameter and height increment correlated positively with gl at the beginning and middle of the night (P < 0.05) but not before dawn. Although our results demonstrate that gl_night was related to tree growth, the relationship was not determined by R. The linkage between gl_predawn and Agross_PAR500 was modified by IR_pday, indicating that daily CO2 assimilation probably provides feedback for stomatal opening before dawn.



中文翻译:

黎明前的叶片电导率取决于前一天的辐照度,但与人工操纵的空气湿度下生长的杨树树苗的生长无关

最近的研究表明,黎明前的气孔开放可以增强早晨的光合作用(A)并提高树木的相对生长率。但是,夜间气孔导度A和树木生长之间的因果关系是有争议的,因为在黑暗中气孔开放可以由前一天的光合产物负荷介导,并且可能是与黑暗呼吸(R)等生长相关的过程的结果。为了确定夜间叶片电导(g l_night),AR和树木生长之间的联系,我们在不同空气相对湿度(RH)条件和前一天辐照水平(IR)下种植的混合白杨树苗中进行了一项实验_pday)。黎明前的叶片电导率(g l_predawn)取决于RH,IR _pdayRP <0.05),而清晨的总AA gross_PAR500)取决于IR _pdayg l_predawnP <0.001)。白天净AA gross_PAR500和叶片[N]正相关(P <0.05)。树木的直径和高度的升高与午夜初半和半午时的g l正相关(P<0.05),但不是在黎明之前。尽管我们的结果表明g l_night与树木生长有关,但该关系不是由R确定的。之间的联系l_predawngross_PAR500通过IR改性_pday,表明每日CO 2同化可能提供了一种用于在黎明前气孔开口的反馈。

更新日期:2020-12-11
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