Global solar radiation has been decreasing, posing a great threat to food security by reducing photo-assimilation and disrupting carbon (C) partitioning in crops like maize. However, practical countermeasures to cope with source-sink balance in periodic shading stress are lacking. Here, we first simulated shading stresses with different degrees and occurring periods on field maize for two years. Results verified that shading-induced yield penalties are most severe around silking and are closely associated with biomass allocation, implying a significant imbalance of source: sink C partitioning during silking. To mitigate yield losses from shading, detasseling (Det) and synchronous pollination (SP), targeting the two sink tissues (tassel and ear, respectively), were applied to 70 % shading at the silking stage in two seasons. Both practices conferred benefits to grain number and yield production, with final yield increases ranging from 4.0 % to 31.3 % under shading. Through 13C labeling, sugar metabolism assay and global analysis, we proved that Det improved the source-sink balance via increasing light irradiance within the canopy and eliminating apical dominance to stimulate C assimilates partitioning into the ear. SP promoted C partitioning into the ear by increasing reproductive sink strength and optimizing assimilates allocation among grain siblings. Intriguingly, Det and SP also provided marginal yield increase under normal light conditions. Our findings underscore the potential of source-sink coordination and C partitioning in mitigating maize yield penalty under environmental stresses like shading. The research also provides new avenues for developing agronomic practices and breeding strategies via tasseling and silking regulation, aiming to improve maize crop production and stress resilience and ensure food security in the face of climate change.

中文翻译：

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在阴影下提高产量：通过优化源-汇碳分配来减轻阴影引起的玉米产量损失


全球太阳辐射一直在减少，通过减少光同化和破坏玉米等作物的碳 （C） 分配，对粮食安全构成巨大威胁。然而，缺乏应对周期性阴影应力中源-汇平衡的实用对策。在这里，我们首先模拟了大田玉米两年来不同程度和发生周期的遮荫胁迫。结果证实，遮荫诱导的产量损失在吐丝周围最为严重，并且与生物量分配密切相关，这意味着吐丝过程中源：汇 C 分区的显着不平衡。为了减少遮荫造成的产量损失，在两个季节的吐丝期，针对两个汇组织（分别为穗和穗）进行了脱粒 （Det） 和同步授粉 （SP） 的 70% 遮光。这两种做法都为谷物数量和产量生产带来了好处，在阴影下，最终产量增加从 4.0% 到 31.3% 不等。通过 13C 标记、糖代谢测定和整体分析，我们证明 Det 通过增加冠内的光辐照度和消除顶端优势来刺激 C 同化物分配到耳朵中，从而改善了源-汇平衡。SP 通过增加生殖汇强度和优化谷物兄弟姐妹之间的同化分配来促进 C 分区到穗中。有趣的是，Det 和 SP 在正常光照条件下也提供了边际产量增加。我们的研究结果强调了源-汇协调和 C 分区在减轻阴影等环境胁迫下玉米产量损失方面的潜力。 该研究还为通过抽穗和吐丝调节来发展农艺实践和育种策略提供了新的途径，旨在提高玉米作物产量和抗逆能力，并确保面对气候变化的粮食安全。