Abstract In riparian forests, light and water are two important factors for plant acclimation to different environments. We evaluated the effect of different light and irrigation regimes on the effective quantum yield of photosystem II (фPSII), the maximum quantum efficiency of photosystem II (Fv/Fm), and the electron transfer rate (ETR) of Magnolia pugana seedlings that come from wild and cultivated plants, under greenhouse conditions. Rapid light curves (RLCs) were performed to obtain the maximum apparent electron transport rate and the saturating photosynthetic photon flux density for PSII. Effective quantum yield of PSII was higher at afternoon for cultivated and wild provenances, but in the latter decreased in longest water deficit treatment at noon. The combined water deficit and high light stress in the morning decreased фPSII; however, фPSII recovered in the afternoon, suggesting dynamic photoinhibition. Furthermore, фPSII of wild and cultivated seedlings in all irrigation levels showed dynamic photoinhibition as well. The electron transfer rate was higher for seedlings grown under high light than in shade. ETR results suggest that wild seedlings showed greater tolerance to water deficit conditions than cultivated ones. Rapid light curves indicate that photosystem II of M. pugana seedlings grown in high light conditions requires higher light intensities to reach saturation. In conclusion, wild and cultivated populations of Magnolia pugana seedlings showed photochemical adjustments to tolerate water deficit and light stress. This study offers new insights into the physiology of endangered plants and valuable guidance for conservation efforts designed at protecting in situ and ex situ wild Magnolia species.

中文翻译：

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光照和灌溉对叶绿素荧光的影响取决于墨西哥特有种 Magnolia pugana 的幼苗来源

摘要 在河岸林中，光和水是植物适应不同环境的两个重要因素。我们评估了不同光照和灌溉制度对光系统 II 的有效量子产率 (фPSII)、光系统 II 的最大量子效率 (Fv/Fm) 以及来自于野生和栽培植物，在温室条件下。进行快速光变曲线 (RLC) 以获得 PSII 的最大表观电子传输速率和饱和光合光子通量密度。栽培种源和野生种源的PSII有效量子产率在下午较高，但在中午最长缺水处理中，后者降低。早晨缺水和高光胁迫共同降低了фPSII；然而，фPSII在下午恢复，表明存在动态光抑制。此外，所有灌溉水平的野生和栽培幼苗的 фPSII 也显示出动态光抑制。在强光下生长的幼苗的电子转移率高于在阴凉处生长的幼苗。ETR 结果表明，野生幼苗比栽培幼苗对缺水条件表现出更大的耐受性。快速光曲线表明，在高光条件下生长的 M. pugana 幼苗的光系统 II 需要更高的光强度才能达到饱和。总之，白玉兰幼苗的野生和栽培种群显示出光化学调整以耐受缺水和光胁迫。