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Background and Aims <p>Rice growth is intimately linked to both the supplied forms of nitrogen (N) and the rhizospheric oxygen (O<sub>2</sub>) environment. While independently beneficial, the mechanisms between these factors remain poorly understood. This study aimed to investigate the synergistic effects of ammonium/nitrate ratios and aerenchyma-mediated radial O<sub>2</sub> loss (ROL) on rice growth and N accumulation.</p> Methods <p>A hydroponic system was employed with five ammonium/nitrate ratios (100/0, 25/75, 50/50, 75/25, and 0/100). γ-aminobutyric acid (GABA) was applied to stimulate root aerenchyma formation and ROL, in a process termed “endogenous oxygenation”. We measured aerenchyma development, N metabolism, and root architecture, constructing Partial Least Squares Structural Equation Modeling (PLS-SEM) to identify drivers of N accumulation.</p> Results <p>Results showed that ammonium/nitrate ratios themselves did not significantly affect root porosity, suggesting no feedback from the nutrient environment to ROL. However, GABA significantly increased root porosity and rhizosphere dissolved O<sub>2</sub> across all N regimes, expanding the rhizospheric oxidation zone. This “endogenous oxygenation” enhanced N-metabolism enzyme activities and root development, notably root length and adventitious roots, significantly increased N accumulation and dry weight, especially at the 50/50 ratio. PLS-SEM revealed that aerenchyma development is the pivotal factor for efficient N utilization, exerting both direct effects and indirect positive impacts by regulating root metabolism and architecture.</p> Conclusion <p>Therefore, manipulating aerenchyma development effectively mitigates seedling hypoxic stress, while synergistically enhancing early growth and N accumulation. Our study provides a novel theoretical strategy for nutrient management within the complex and dynamically-shifting ammonium-nitrate environments in paddy fields.</p>

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Aerenchyma optimization enhances nitrate-ammonium synergism in rice

  • 期刊论文

  • 发表日期：

    2026年7月28日

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  • Zhenglun Yu,
  • Herbert J. Kronzucker,
  • Lingjia Liang,
  • Weiming Shi,
  • Yilin Li

摘要

Background and Aims

Rice growth is intimately linked to both the supplied forms of nitrogen (N) and the rhizospheric oxygen (O2) environment. While independently beneficial, the mechanisms between these factors remain poorly understood. This study aimed to investigate the synergistic effects of ammonium/nitrate ratios and aerenchyma-mediated radial O2 loss (ROL) on rice growth and N accumulation.

Methods

A hydroponic system was employed with five ammonium/nitrate ratios (100/0, 25/75, 50/50, 75/25, and 0/100). γ-aminobutyric acid (GABA) was applied to stimulate root aerenchyma formation and ROL, in a process termed “endogenous oxygenation”. We measured aerenchyma development, N metabolism, and root architecture, constructing Partial Least Squares Structural Equation Modeling (PLS-SEM) to identify drivers of N accumulation.

Results

Results showed that ammonium/nitrate ratios themselves did not significantly affect root porosity, suggesting no feedback from the nutrient environment to ROL. However, GABA significantly increased root porosity and rhizosphere dissolved O2 across all N regimes, expanding the rhizospheric oxidation zone. This “endogenous oxygenation” enhanced N-metabolism enzyme activities and root development, notably root length and adventitious roots, significantly increased N accumulation and dry weight, especially at the 50/50 ratio. PLS-SEM revealed that aerenchyma development is the pivotal factor for efficient N utilization, exerting both direct effects and indirect positive impacts by regulating root metabolism and architecture.

Conclusion

Therefore, manipulating aerenchyma development effectively mitigates seedling hypoxic stress, while synergistically enhancing early growth and N accumulation. Our study provides a novel theoretical strategy for nutrient management within the complex and dynamically-shifting ammonium-nitrate environments in paddy fields.