Context

Numerous studies have shown that appropriate nitrogen (N) positively affects wheat yield increase, while excessive N decreases stem resistance to lodging and reduce yield. In comparison, photosynthetic carbon allocation in wheat leaves plays a crucial role in yield formation (spike) and resistance to lodging (stem).

Research question

This study aimed to determine why high N fertilizer increases the risk of wheat stem lodging and how N fertilization regulates photosynthetic carbon allocation to harmonize the balance between wheat yield and stem quality.

Methods

We used four N levels of 0 (N0), 120 (N1), 240 (N2), and 360 kg ha⁻¹ (N3) with Jimai 22 (JM22), Shannong16 (SN16), and Taikemai 33 (TK33) as experimental materials.

Results

Per increase of 120 kg ha⁻¹ of N fertilizer, the breaking moment of stem decreased by 13.51–24.67%; stem nonstructural carbohydrate (soluble sugar and starch) content decreased by 1.83–5.11% and 3.59–10.23%; structural carbohydrate (cellulose and lignin) content decreased by 8.13–14.59% and 11.23–18.01%. Photosynthesis of leaves led to an increase in starch content of 30.79 mg g⁻¹ 12 h⁻¹ during the day, and starch was continuously broken down, leading to an increase in soluble sugar content of 18.15 mg g⁻¹ 12 h⁻¹. The stems used the soluble sugars obtained from the leaves to synthesize structural carbohydrates to ensure their quality.

Conclusions and implications

N application increased the content of soluble sugars in the leaves. It showed that the leaves could produce enough substrate for the stems. However, stems could not fully utilize the carbohydrates produced by leaves to synthesize sufficient lignin and cellulose, resulting in poor stem quality. Therefore, in the future, improving the ability of stems to assimilate and utilize carbohydrates will be the key to ensuring the quality of stems and improving the resistance of wheat to lodging.

中文翻译：

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氮素通过打破小麦光合碳分配平衡调控茎秆抗倒伏性

语境

大量研究表明，适量的氮肥对小麦增产有积极影响，而过量的氮肥会降低茎秆的抗倒伏性并降低产量。相比之下，小麦叶片的光合碳分配在产量形成（穗）和抗倒伏（茎）中起着至关重要的作用。

研究问题

本研究旨在确定为什么高氮肥会增加小麦茎倒伏的风险，以及施氮如何调节光合碳分配以协调小麦产量和茎质量之间的平衡。

方法

我们使用 0 (N0)、120 (N1)、240 (N2) 和 360 kg ha ⁻¹ (N3) 四个 N 水平，其中济麦 22 (JM22)、山农 16 (SN16) 和泰科麦 33 (TK33) 作为试验材料。

结果

氮肥每增加120 kg ha ^{−1 ，茎干断裂力矩降低13.51%～24.67%；}茎非结构碳水化合物（可溶性糖和淀粉）含量分别下降1.83-5.11%和3.59-10.23%；结构碳水化合物（纤维素和木质素）含量分别下降了 8.13-14.59% 和 11.23-18.01%。叶片的光合作用导致白天淀粉含量增加30.79 mg g ^-1 12 h ^{-1 ，淀粉不断分解，导致可溶性糖含量增加18.15 mg g -1} 12 h ^-1。茎利用从叶子中获得的可溶性糖合成结构性碳水化合物以确保其质量。

结论和启示

施氮增加了叶片中可溶性糖的含量。它表明叶子可以为茎产生足够的基质。然而，茎不能充分利用叶子产生的碳水化合物合成足够的木质素和纤维素，导致茎质量差。因此，今后提高茎秆同化利用碳水化合物的能力将是保证茎秆品质、提高小麦抗倒伏能力的关键。