Du Tingting, Ling Xiaoxia, Huang Jianliang, Peng Shaobing, Xiong Dongliang
National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China.
Physiol Plant. 2024 Mar-Apr;176(2):e14241. doi: 10.1111/ppl.14241.
Vein severing in plants caused by leaf damage is common in fields where crops are cultivated. It is hypothesized that leaves with complex reticulate venation can withstand hydraulic disturbances caused by vein severing, thereby preserving leaf carbon assimilation. However, limited research focuses on vein damage of leaves with parallel venation. We studied how vein-severing affected the photosynthetic traits of rice (Oryza sativa) leaves in seconds, minutes and days, under varying water-demand conditions and differing extents of water supply disruption. Rice leaves completely lost their photosynthetic capacity within 2.5 minutes after excision. Severing the midrib resulted in reduced light-saturated photosynthetic rate (A), stomatal conductance (g ) and transpiration rate (E) by 2.6, 6.8 and 5.9%, respectively, already after thirty minutes. We further investigated the photosynthetic trait responses to various extents of leaf width severing, while keeping the midrib functional. Surprisingly, A, g and E in the downstream area of the severed leaves largely remained stable, showing minimal variation across different leaf width severing ratios. These traits declined only slightly even under increased ambient light intensity and leaf-to-air vapor pressure deficit. This sustained photosynthesis post-severing is attributed to the efficient lateral water transport. Long-term leaf damage slightly but not significantly, impacted the downstream photosynthetic traits within five days post-severing. However, a more pronounced reduction in gas exchange during leaf senescence was observed nine days after severing. These findings suggested that rice leaves can tolerate hydraulic disturbances from vein severing and maintain functionality under various conditions, which is crucial for crop yield stability. However, long-term consequences require further investigation.
在种植作物的田间，因叶片损伤导致的植物叶脉切断现象很常见。据推测，具有复杂网状叶脉的叶片能够抵御叶脉切断引起的水力干扰，从而保持叶片的碳同化作用。然而，针对平行叶脉叶片的叶脉损伤研究较少。我们研究了在不同需水条件和不同程度的供水中断情况下，叶脉切断在数秒、数分钟和数天内对水稻（Oryza sativa）叶片光合特性的影响。水稻叶片在切除后2.5分钟内完全丧失光合能力。切断中脉后，仅30分钟，光饱和光合速率（A）、气孔导度（g）和蒸腾速率（E）就分别降低了2.6%、6.8%和5.9%。我们进一步研究了在保持中脉功能的同时，不同程度叶片宽度切断对光合特性的响应。令人惊讶的是，切断叶片下游区域的A、g和E基本保持稳定，在不同叶片宽度切断比例下变化极小。即使在环境光强增加和叶 - 气蒸汽压差增大的情况下，这些特性也仅略有下降。切断后光合作用的持续进行归因于高效的侧向水分运输。长期叶片损伤在切断后五天内对下游光合特性有轻微但不显著的影响。然而，切断九天后，在叶片衰老过程中观察到气体交换有更明显的下降。这些发现表明，水稻叶片能够耐受叶脉切断引起的水力干扰，并在各种条件下维持功能，这对作物产量稳定性至关重要。然而，长期影响还需要进一步研究。
