Saline–alkaline stress suppresses rice growth and threatens crop production. Despite substantial research on rice’s tolerance to saline–alkaline stress, fewer studies have examined the impact of magnetic water treatments on saline–alkaline-stressed rice plants. We explored the physiological and molecular mechanisms involved in saline–alkaline stress tolerance enhancement via irrigation with magnetized water using Nipponbare. The growth of Nipponbare plants was inhibited by saline–alkaline stress, but this inhibition was alleviated by irrigating the plants with magnetized water, as evidenced by greater plant height, biomass, chlorophyll content, photosynthetic rates, and root system in plants irrigated with magnetized water compared to those irrigated with non-magnetized water. Plants that were irrigated with magnetized water were able to acquire more total nitrogen. In addition, we proved that rice seedlings irrigated with magnetized water had a greater root NO₃⁻-nitrogen concentration and root NH₄⁺-nitrogen concentration than plants irrigated with non-magnetized water. These findings suggest that treatment with magnetized water could increase nitrogen uptake. To test this hypothesis, we analyzed the expression levels of genes involved in nitrogen acquisition. The expression levels of OsNRT1;1, OsNRT1;2, OsNRT2;1, OsAMT1;2, OsAMT2;1, OsAMT2;2, OsAMT2;3, OsAMT3;1, OsAMT3;2, and OsAMT3;3 were higher in plants exposed to magnetized water medium compared to those exposed to non-magnetized water media. We further demonstrated that treatment with magnetized water increases available nitrogen, NO₃⁻-nitrogen content, and NH₄⁺-nitrogen content in soil under saline–alkaline stress. Our results revealed that the increased resistance of rice seedlings to saline–alkaline stress may be attributable to a very effective nitrogen acquisition system enhanced by magnetized water.

Introduction: Saline-alkaline soils pose significant constraints to sustainable wheat production through impaired nutrient cycling and reduced crop productivity. While straw return and biostimulants are recognized management strategies, their combined effects on soil nutrient dynamics and yield-quality relationships remain poorly understood. Methods: A two-year field experiment was conducted under mildly saline-alkaline conditions with four treatments: control (CK), straw return (SR), biostimulant foliar application (BS), and integrated straw return with biostimulant (SR+BS). Soil biochemical properties, enzyme activities, crop physiological parameters, yield components, and grain quality were evaluated. Results: The SR+BS treatment significantly enhanced soil organic carbon (28.3%) and total nitrogen (19.6%) compared to the control. Soil enzyme activities increased markedly, with sucrase, urease, alkaline phosphatase, and catalase showing increases of 67.9%, 32.1%, 47.6%, and 44.5%, respectively. Soil inorganic nitrogen availability was substantially enhanced, with NH ₄ ⁺ -N and NO ₃ ⁻ -N increasing by 47.7% and 39.8%. These improvements were associated with enhanced crop performance: leaf area index and dry matter accumulation increased by 37.5% and 49.1%, respectively. Grain yield reached 8770 kg ha ⁻¹ (a 40.8% increase), while grain protein content reached 16.4% (a 25.2% increase), demonstrating improved yield-quality relationships under stress conditions. Discussion: These findings indicate that integrated straw return with biostimulant application drives a cascade-like response — from enhanced soil carbon-nitrogen supply through improved physiological processes to increased crop productivity. This integrated strategy offers a promising and sustainable intensification approach for wheat production in saline-alkaline agroecosystems.

Shallow groundwater in saline soils creates a self-reinforcing cycle where waterlogging-induced root hypoxia impairs the ATP-dependent sodium exclusion mechanisms that plants rely on for salt tolerance. We conducted a two-year field experiment to test whether subsurface drainage must precede root-zone aeration for oxygen delivery to be effective. The experimental site was located in Heyang County, Weinan City, on the Guanzhong Plain of Shaanxi Province, north-central China—a major alluvial agricultural region representative of shallow-groundwater-induced salinization. The site had saturated paste electrical conductivity of 6.0 dS m⁻¹ and groundwater depth fluctuating between 0.5 and 1.4 m. A randomized complete block design with 2 × 2 factorial arrangement compared four treatments: control (CK), subsurface drainage only (SD), root-zone aeration only (RA), and both interventions combined (SD + RA). Drainage increased air-filled porosity from 5.8% to 13.5%, crossing the 10.2% threshold (95% CI: 9.1–11.3%) where gas-phase continuity emerges according to segmented regression analysis. Without drainage, aeration achieved only 4.2 mg L⁻¹ dissolved oxygen with high spatial variability (CV 12.5%), while the combined treatment reached 6.8 mg L⁻¹ (CV 6.8%). Root ATP content increased by 89% in SD + RA compared to control, accompanied by 56% lower root Na⁺ and 185% higher K⁺/Na⁺ ratio. These physiological changes correlated with 31% higher grain yield (7580 vs. 5798 kg ha⁻¹). The synergy index of 1.40 (95% CI: 1.28–1.52) indicated that combined effects exceeded the sum of individual treatments by 40%. Methane emissions declined by 62%, and the system achieved a 2.9-year payback period with a benefit–cost ratio of 4.08. These results establish drainage as a physical prerequisite for effective oxygenation, providing a mechanistic explanation for the variable performance of aeration systems reported in previous studies.

How nitrogen (N) supply should be matched to increased planting density in drip-fertigated maize in arid regions remains unclear. A two-year split-plot field experiment (2024–2025) at Shihezi, northern Xinjiang, China, tested two planting densities (D1, 60,000; D2, 90,000 plants ha⁻¹) and two N rates (N1, 180; N2, 240 kg N ha⁻¹) in film-mulched, drip-irrigated spring maize. D2 increased grain yield by 13.9% over D1, because a 46.8% increase in ear number outweighed decreases in kernels per ear and kernel weight. The yield response to N depended on density (D × N, p < 0.01): N2 increased yield by 13.8% under D2 but by only 3.6% (not significant) under D1. N2 increased N accumulation at silking similarly at both densities, whereas its post-silking effects were much larger under D2, where it reduced the post-silking decline in leaf area index from 67.3% to 51.2% and increased post-silking dry matter accumulation and apparent N uptake by 22.0% and 44.3%. D2N2 produced the highest yield (11.51 t ha⁻¹), whereas D2N1 achieved the highest partial factor productivity of N (56.2 kg kg⁻¹). At this single site, dense planting benefited more from the higher N rate, most evidently after silking; validation across sites, hybrids, and N rates is needed.