Abstract The relationship between photosynthesis performance under drought stress and osmotic and elastic adjustments has yielded contrasting results so far, despite the potential role of water relations in turgor maintenance and stomatal functioning. Photosynthesis and pressure-volume derived parameters were investigated in Arbutus unedo old and young leaves after two months of limited water availability. Young and old leaves were clearly differentiated in CO2 assimilation rate and its underlying mechanisms, modulus of elasticity and leaf structure under well-watered conditions. Additionally, their response to drought stress differed: old leaves were able to sustain similar assimilation values, whereas photosynthesis and stomatal conductance were significantly reduced in young leaves. Elastic adjustment and other elasticity-related parameters were also different depending on leaf age, with no apparent relationship with basic cell wall composition. Although the mechanisms of elastic adjustment are not clear from the presented results, such adjustment apparently contributes to regulate the photosynthetic response under drought stress by maintenance of turgor and hence stomatal aperture.

中文翻译：

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杨梅幼苗干旱胁迫下的叶龄依赖性弹性调节和光合性能

摘要 尽管水分关系在膨压维持和气孔功能中具有潜在作用，但迄今为止，干旱胁迫下的光合作用性能与渗透和弹性调节之间的关系产生了截然不同的结果。在两个月的有限水分供应后，研究了杨梅老叶和幼叶的光合作用和压力-体积衍生参数。在充分浇水条件下，新叶和老叶在 CO2 同化率及其潜在机制、弹性模量和叶结构方面明显不同。此外，它们对干旱胁迫的反应不同：老叶能够维持相似的同化值，而幼叶的光合作用和气孔导度显着降低。弹性调整和其他弹性相关参数也因叶龄而异，与基本细胞壁组成没有明显关系。虽然弹性调节的机制从所呈现的结果中尚不清楚，但这种调节显然有助于通过维持膨压和气孔孔径来调节干旱胁迫下的光合反应。