Abstract: Photosynthetic product allocation strategy is a crucial mechanism for plants to cope with stressful disturbance and enhance their environmental adaptation. In this study， we investigated the dynamic effects of mowing intensity on the allocation of photosynthetic products in C₄ herbaceous plant （Cynodon dactylon） by using the ¹³C pulse labeling technique. The results showed that mowing significantly influenced the δ¹³C allocation ratios in leaves， stems， and roots （P<0.001）， as well as the contents of non-structural carbohydrates （NSC） （P<0.001） and secondary metabolites （SM） （P<0.05）. After mowing， C. dactylon significantly increased the δ¹³C allocation ratio to leaves while decreasing the ratio to stems （P<0.05）. Mowing significantly reduced NSC and SM contents in roots but increased SM content in stems. Under light and moderate mowing， leaf NSC content significantly increased， whereas heavy mowing led to a significantly higher leaf SM content compared to other treatments （P<0.05）. With the extension of recovery time， light mowing gradually reduced the δ¹³C allocation ratio to leaves， while heavy mowing further decreased the ratio to stems and increased allocation to leaves and roots. These findings would provide a reference for the scientific and rational management of artificial grassland.

Key words: C₄ plant, Photosynthetic product allocation, Cynodon dactylon, Mowing, ¹³C pulse labeling

摘要： 光合产物分配策略是植物应对胁迫干扰和增强环境适应性的重要手段，本研究以C₄草本植物狗牙根（Cynodon dactylon）为研究对象，基于¹³C脉冲标记技术，探究刈割强度对狗牙根光合产物分配的动态影响。结果表明：刈割显著影响狗牙根叶、茎和根的δ¹³C分配比例（P<0.001）、非结构性碳水化合物（Non structural carbohydrates， NSC）（P<0.001）和次生代谢物（Secondary metabolites， SM）含量（P<0.05）；刈割后狗牙根显著增加叶片的δ¹³C分配比例，显著降低茎部的δ¹³C分配比例（P<0.05）；刈割显著降低狗牙根的根系NSC和SM含量，显著增加茎部的SM含量，轻、中度刈割下狗牙根叶片NSC含量均显著增加，重度刈割下狗牙根叶片SM含量显著高于其他处理（P<0.05）；随恢复时间的延长，轻度刈割会逐渐降低叶片的δ¹³C分配比例，重度刈割会进一步降低茎的δ¹³C分配比例，增加叶片和根系的δ¹³C分配比例。研究结果将为科学合理地管理人工草地提供参考依据。

关键词: C₄植物, 光合产物分配, 狗牙根, 刈割, ¹³C脉冲标记