Objectives In response to the challenge of limited water resources and the difficulty in ensuring a sustainable water supply for crops in arid areas, this study innovatively introduces a negative pressure irrigation system. The aim is to explore in depth how negative pressure irrigation affects the physiological functional characteristics and nitrogen metabolism of maize under drought stress, providing new scientific strategies and technical support for agricultural irrigation in arid regions.

Methods The experiment was conducted at the experimental base of Heilongjiang Bayi Agricultural University in Heilongjiang Province. Four treatments were set up: negative pressure irrigation under drought stress at −10 kPa (H1), artificial irrigation under drought stress (H2), negative pressure irrigation under drought stress at −15 kPa (H3), and conventional watering (CK). Negative pressure irrigation was applied throughout the entire growth period for H1 and H3 treatments to study changes in maize growth, yield, and nitrogen metabolism-related indicators.

Results During the jointing, heading, filling, maturity stages of maize, the soil moisture content of CK treatment was 80.0% to 90.4% of the field capacity, H1 treatment remained stable at 49.9% to 53.0% of the field capacity, H2 treatment was 29.1% to 46.8% of the field capacity, and H3 treatment was 38.6% to 41.4% of the field capacity. Plant height in H1 increased by 64.4%, 29.8%, 19.5%, and 20.1% compared to H2 plants. During the tasseling and maturation stages, the stem diameter of H1 treatment decreased by 48.4% and 49.3% compared to CK treatment; during the jointing stage, the stem diameter of H1 treatment was significantly higher than that of H2 treatment, while there was no significant difference between H1 and H2 treatments during other growth stages. In the four growth stages, the dry matter accumulation of maize under H1 treatment was increased by 20.2%−44.8% compared with H2 treatment. The nitrogen absorption of H1 treatment was increased by 43.1%−151.9% compared with H2 treatment. From jointing stage to maturity stage, the nitrate reductase activity of maize showed a continuous increase trend, and H1 treatment was the highest, which was 24.8%−99.9% higher than CK treatment, 41.6%−427.4% higher than H2 treatment and 25.8%−94.0% higher than H3 treatment, respectively. Glutamate dehydrogenase (GDH) activity of H1 treatment was 118.9%−156.4% higher than that of CK treatment, 255.4%−293.5% higher than that of H2 treatment, and 84.5%−98.4% higher than that of H3 treatment, respectively. The activity of glutamate pyruvate transaminase (GPT) in H1 treatment was increased by 35.8%−81.8% compared with CK treatment, 111.9%−194.3% compared with H2 treatment, and 21.6%−90.9% compared with H3 treatment. From jointing stage to maturity stage, the nitrate nitrogen content of H1 treatment was increased by 152.3% to 296.7% compared with H2 treatment, 36.9% to 89.4% compared with H3 treatment and 62.6% to 162.7% compared with CK treatment. The amino acid content of H1 treatment was increased by 39.4%−139.6% compared with H2 treatment, 15.2%−87.2% compared with H3 treatment and 41.3%−67.8% compared with CK treatment. At the maturity stage, there was no significant difference in yield between CK and H1 treatment, and the yield of H1 treatment was 206.4% and 134.7% higher than that of H2 and H3 treatment, respectively.

Conclusions Under drought stress, negative pressure irrigation at −10 kPa has a significant positive effect on maize growth. Compared with artificial irrigation under drought stress, it can increase plant height, stem diameter, dry matter accumulation, and yield, enhance nitrogen metabolism, promote nitrogen absorption and utilization in maize, and significantly improve nitrogen uptake.