Effects of Water–Nitrogen Coupling on Root Distribution and Yield of Summer Maize at Different Growth Stages
Yanbin Li, Qian Wang, Shikai Gao, Xiaomeng Wang, Aofeng He, Pengcheng He
Abstract
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−1, split-applied at 50% during sowing and 50% at the jointing stage, labeled as N1, N2, and N3) at the two critical growth stages (jointing stage P1 and tasseling-silking stage P2) of maize (Denghai 605). The results demonstrated that maize root morphological parameters exhibited the trend N2 > N1 > N3 under different nitrogen treatments. Compared to N2, low nitrogen (N1) decreased root morphological parameters by 35.01–49.60% on average, whereas high nitrogen (N3) led to a reduction of 49.93–61.37%. The N2 treatment consistently maintained greater water uptake, with the highest yield of 13,336 kg·ha−1 observed under the CKN2 treatment, representing increases of 16.1% and 9.2% compared to the P1N2 and P2N2 treatments, respectively. Drought stress at the jointing stage (P1) inhibited root development more severely than at the tasseling-silking stage (P2), 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 (p < 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.