This study was aimed to investigate how exogenous manganese (Mn) would limit damage in the oxygen-evolving complex (OEC) and photosynthetic apparatus of maize seedlings caused during seawater vulnerability. In this study, seawater was applied in 2-week-old maize (Zea mays L.) seedling, and the degree of damage of photosynthetic pigment pool, the OEC, and net electron transport rate were observed. Mn supplement was also added in maize seedlings to limit the damage of the OEC and photosynthetic apparatus caused during salinity. Leaf relative water content (RWC), fresh weight (FW), and photosynthetic pigment pool (chlorophyll a, chlorophyll b, and carotenoids) sharply declined after 7 days of treatment; however, Mn supplement increased these values. Chlorophyll fluorescence induction (OJIP) transients showed low Fv/Fo, an additional K step, enhanced variable fluorescence (VK) and degree of damage to the OEC (WK) during salinity, and indicates damage of OEC at electron donor side of photosystem II (PSII). The OEC intact within PSII was a primary damage center during salinity which inhibited electron transport process that resulted in a huge loss of maximum quantum yield of PSII (Fv/Fm), but a significant recovery in photosynthetic apparatus was observed after exogenous application of manganese. Structural and functional integrity of the photosynthetic apparatus was recovered up to a certain extent after exogenous application of Mn. Findings from this study should help to understand the basic knowledge of photosynthetic apparatus efficiency in response to damage caused by exposure to seawater. Outcomes of this study will be used to mitigate salinity problem with Mn supplement for growth and development of crops.

中文翻译：

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锰在海水脆弱性期间修复玉米（Zea mays L.）中的氧气释放复合物（OEC）

本研究旨在研究外源锰 (Mn) 如何限制在海水脆弱期间对玉米幼苗的氧气释放复合体 (OEC) 和光合装置造成的损害。本研究对2周龄的玉米(Zea mays L.)幼苗施海水，观察光合色素库的破坏程度、OEC和净电子传递率。在玉米幼苗中还添加了锰，以限制盐化过程中对 OEC 和光合装置的损害。处理7天后，叶片相对含水量（RWC）、鲜重（FW）和光合色素库（叶绿素a、叶绿素b和类胡萝卜素）急剧下降；然而，锰补充剂增加了这些值。叶绿素荧光诱导 (OJIP) 瞬变显示低 Fv/Fo，额外的 K 步骤，在盐度期间增强可变荧光 (VK) 和 OEC (WK) 的损坏程度，并表明光系统 II (PSII) 电子供体侧的 OEC 损坏。PSII内完整的OEC是盐度过程中的主要损伤中心，它抑制了电子传输过程，导致PSII最大量子产率（Fv / Fm）的巨大损失，但在外源施用锰后观察到光合装置的显着恢复。外源施用锰后，光合装置的结构和功能完整性得到了一定程度的恢复。这项研究的结果应该有助于理解光合装置效率对暴露于海水造成的损害做出反应的基本知识。