Peña-Rojas Karen, Aranda Xavier, Joffre Richard, Fleck Isabel
Departament de Biologia Vegetal, Unitat Fisiologia Vegetal, Facultat Biologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.
Dream Unit, Centre d'Ecologie Fonctionnelle et Evolutive CNRS, 1919 Route de Mende, 34293 Montpellier cedex 5, France.
Funct Plant Biol. 2005 Apr;32(2):117-130. doi: 10.1071/FP04137.
Functional and morphological (structural) characteristics of Quercus ilex L. leaves under drought stress were studied in the forest and in a nursery. We compared undisturbed individuals (controls) with resprouts emerging after clear-cut or excision. When soil water availability was high, gas-exchange was similar in resprouts and controls, despite higher midday leaf water potential, midday leaf hydration and relative water content (RWC). In moderate drought, stomatal closure was found to limit photosynthesis in controls, and in severe drought non-stomatal limitations of photosynthesis were also greater than in resprouts. Leaf structure and chemical composition changed under drought stress. Leaves tended to be smaller in controls with increasing drought, and resprouts had larger leaves and lower leaf mass area (LMA). The relationship between nitrogen (N) content and LMA implied lower N investment in photosynthetic components in controls, which could be responsible for their increased non-stomatal limitation of photosynthesis. Changes were more apparent in leaf density (D) and thickness (T), components of LMA. Decreases in D were related to reductions in cell wall components: hemicellulose, cellulose and lignin. In resprouts, reduced D and leaf T accounted for the higher mesophyll conductance (g) to CO measured.
在森林和苗圃中研究了干旱胁迫下冬青栎叶片的功能和形态（结构）特征。我们将未受干扰的个体（对照）与皆伐或切除后萌出的新芽进行了比较。当土壤水分充足时，尽管中午叶片水势、中午叶片水合作用和相对含水量（RWC）较高，但新芽和对照的气体交换相似。在中度干旱时，发现气孔关闭限制了对照中的光合作用，而在严重干旱时，光合作用的非气孔限制也比新芽更大。干旱胁迫下叶片结构和化学成分发生了变化。随着干旱加剧，对照中的叶片往往变小，新芽的叶片更大且叶面积质量（LMA）更低。氮（N）含量与LMA之间的关系表明对照中光合组分的氮投入较低，这可能是其光合作用非气孔限制增加的原因。叶密度（D）和厚度（T）（LMA的组成部分）的变化更为明显。D的降低与细胞壁成分（半纤维素、纤维素和木质素）的减少有关。在新芽中，D和叶片T的降低导致测量到的叶肉对CO的导度（g）较高。
