Effects of Water-Nitrogen Coupling on Root Distribution and Yield of Summer Maize at Different Growth Stages.

This research investigates the influence of water-nitrogen coupling on soil water content, nitrogen dynamics, and root distribution in farmland, along with the interactions among soil water, nitrogen transport, root distribution, and crop yield. A field experiment was conducted under moderate drought stress (50-60% of field capacity) and three nitrogen application rates (100, 200, and 300 kg·ha, split-applied at 50% during sowing and 50% at the jointing stage, labeled as N, N, and N) at the two critical growth stages (jointing stage P and tasseling-silking stage P) of maize (). The results demonstrated that maize root morphological parameters exhibited the trend N > N > N under different nitrogen treatments. Compared to N, low nitrogen (N) decreased root morphological parameters by 35.01-49.60% on average, whereas high nitrogen (N) led to a reduction of 49.93-61.37%. The N treatment consistently maintained greater water uptake, with the highest yield of 13,336 kg·ha observed under the CKN treatment, representing increases of 16.1% and 9.2% compared to the PN and PN treatments, respectively. Drought stress at the jointing stage (P) inhibited root development more severely than at the tasseling-silking stage (P), demonstrating a bidirectional adaptation strategy characterized by deeper vertical penetration under water stress and increased horizontal expansion under nitrogen imbalance. Correlation analysis revealed a positive correlation between soil nutrient content and maize yield indicators. At the same time, root characteristic values were significantly negatively correlated with yield ( < 0.05). Appropriate water-nitrogen management effectively stimulated root growth, mitigated nitrogen leaching risks, and improved yield. These findings offer a theoretical foundation for optimizing water and nitrogen management in maize production within the Yellow River Basin.