Low light conditions not only induce leaf senescence, but also photosynthetic acclimation. This study aimed to determine whether plants exhibit photosynthetic acclimation during low-light-induced leaf senescence. The influences of shading on leaf senescence and photosynthetic acclimation were explored in post-anthesis maize plants. The results showed that whole shading (WS) of maize plants accelerated leaf senescence, whereas partial shading (PS) slowed leaf senescence. WS led to larger decreases in the photosynthetic rate (P_n) and stomatal conductance (G_s) compared to those of the PS treatment. Interestingly, chlorophyll a fluorescence (ChlF) demonstrated that the absorption flux (ABS/CS_o) and trapped energy flux (TR_o/CS_o) per cross section in leaves remained relatively stable under WS, whereas significant decreases in the active PSII reaction centers (RC/CS_o) resulted in considerable increases in absorption (ABS/RC) and trapped energy flux (TR_o/RC) per reaction center. ABS/CS_o, TR_o/CS_o, ABS/RC, and TR_o/RC increased markedly under PS, whereas there were slight decreases in RC/CS_o and electron transport activity. These results suggest that the PS treatment resulted in obvious improvements in the absorption and capture of light energy in shaded leaves. Further analysis demonstrated that both the WS and PS treatments resulted in a greater decrease in the activity of Rubisco compared to that of phosphoenolpyruvate carboxylase (PEPC). Moreover, PEPC activity in PS was maintained at a high level. Consequently, the current study proposed that the improvement of the absorption and capture of light energy and the maintenance of PEPC activity of mesophyll cells were due to photosynthetic acclimation of low-light-induced leaf senescence in maize plants. In addition, the rate of senescence of vascular bundle cells in maize leaves exceeded that of mesophyll cells under low light, showing obvious tissue specificity.

弱光条件不仅会导致叶片衰老，还会导致光合适应。本研究旨在确定植物在弱光诱导的叶片衰老过程中是否表现出光合适应。在开花后的玉米植物中探讨了遮光对叶片衰老和光合驯化的影响。结果表明，玉米植株全遮光（WS）加速叶片衰老，而部分遮光（PS）减缓叶片衰老。与 PS 处理相比，WS 导致光合速率 (P _n ) 和气孔导度 (G _{s ) 下降幅度更大。}有趣的是，叶绿素a 荧光 (ChlF) 表明吸收通量 (ABS/CS _o ) 和俘获能量通量 (TR _o/CS _o ) 每个叶片横截面在 WS 下保持相对稳定，而活性 PSII 反应中心 (RC/CS _o ) 的显着降低导致吸收 (ABS/RC) 和捕获的能量通量 (TR _o /RC ) 显着增加) 每个反应中心。PS下ABS/CS _o、TR _o /CS _o、ABS/RC 、TR _o /RC显着增加，而RC/CS _{o略有下降}和电子传输活性。这些结果表明，PS 处理明显改善了阴影叶片对光能的吸收和捕获。进一步的分析表明，与磷酸烯醇丙酮酸羧化酶 (PEPC) 相比，WS 和 PS 处理都导致 Rubisco 的活性下降幅度更大。此外，PS中的PEPC活性保持在高水平。因此，目前的研究提出，光能吸收和捕获的改善以及叶肉细胞PEPC活性的维持是由于玉米植物对弱光诱导的叶片衰老的光合作用适应。此外，玉米叶片维管束细胞在弱光下的衰老速度超过了叶肉细胞，表现出明显的组织特异性。