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首页> 外文期刊>Journal of Experimental Botany >Soil water deficits decrease the internal conductance to CO transfer but atmospheric water deficits do not.
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Soil water deficits decrease the internal conductance to CO transfer but atmospheric water deficits do not.

机译：土壤缺水会降低内部向CO传递的电导率，而大气缺水不会。

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The internal conductance to CO supply from substomatal cavities to sites of carboxylation poses a large limitation to photosynthesis. It is known that internal conductance is decreased by soil water deficits, but it is not known if it is affected by atmospheric water deficits (i.e. leaf to air vapour pressure deficit, VPD). The aim of this paper was to examine the responses of internal conductance to atmospheric and soil water deficits in seedlings of the evergreen perennial Eucalyptus regnans F. Muell and the herbaceous plants Solanum lycopersicum (formerly Lycopersicon esculentum) Mill. and Phaseolus vulgaris L. Internal conductance was estimated with the variable J method from concurrent measurements of gas exchange and fluorescence. In all three species steady-state stomatal conductance decreased by ~30% as VPD increased from 1 kPa to 2 kPa. In no species was internal conductance affected by VPD despite large effects on stomatal conductance. In contrast, soil water deficits decreased stomatal conductance and internal conductance of all three species. Decreases in stomatal and internal conductance under water deficit were proportional, but this proportionality differed among species, and thus the relationship between stomatal and internal conductance differed among species. These findings indicate that soil water deficits affect internal conductance while atmospheric water deficits do not. The reasons for this distinction are unknown but are consistent with soil and atmospheric water deficits having differing effects on leaf physiology and/or root-shoot communication.
机译：从气孔下腔到羧化位点的CO供应的内部电导率对光合作用构成了很大的限制。已知内部电导因土壤缺水而降低，但是尚不清楚其是否受到大气缺水的影响（即叶对空气蒸汽压亏缺，VPD）。本文的目的是研究常绿多年生的多年生尤加利桉树F.Muell种子和草本植物茄兰（Lycopersicon esculentum）Mill的内部电导对大气和土壤水分亏缺的响应。通过同时测量气体交换和荧光，使用变量J方法估计内部电导。随着VPD从1 kPa增加到2 kPa，这三种物种的稳态气孔导度都降低了约30％。尽管对气孔电导有很大影响，但没有一种物种的内部电导受到VPD的影响。相比之下，土壤水分亏缺降低了所有三种物种的气孔导度和内部导度。水分亏缺下气孔和内部电导的降低是成比例的，但是这种比例在物种之间是不同的，因此物种之间的气孔和内部电导之间的关系是不同的。这些发现表明，土壤水分亏缺会影响内部电导率，而大气水分亏缺不会。这种区别的原因尚不清楚，但与土壤和大气缺水对叶片生理和/或根冠通讯产生不同影响是一致的。

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