Zhou Hui, Guo Jiawei, Wang Yongqiang, Wang Jian, Liu Hu
Yinshanbeilu Grassland Eco-Hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing, China.
Institute of Water Resources for Pastoral Area Ministry of Water Resources, Hohhot, China.
Front Plant Sci. 2025 Aug 8;16:1587533. doi: 10.3389/fpls.2025.1587533. eCollection 2025.
Soil salinization is a major constraint to crop production in arid and semi-arid regions. Combined application of organic and inorganic nitrogen (OIN) has been recognized as an effective strategy to improve productivity in saline soils. However, mechanisms underlying yield improvement related to photosynthesis and antioxidant responses remain unclear.
A field experiment was conducted from 2018 to 2020 in the Hetao Irrigation District of Inner Mongolia using mildly saline soil (S1, EC = 0.68 dS m⁻¹) and moderately saline soil (S2, EC = 1.25 dS m⁻¹). Six nitrogen treatments were applied: no nitrogen (CK), inorganic nitrogen only (U1), and organic nitrogen replacing 25%, 50%, 75%, and 100% of inorganic nitrogen (U3O1, U1O1, U1O3, and O1). Maize growth, photosynthetic parameters, and antioxidant enzyme activities were measured.
Under S1 conditions, OIN significantly enhanced leaf area index (LAI), photosynthetic performance, superoxide dismutase (SOD) activity, and yield, with U1O1 yielding the highest production. Under S2 conditions, growth and photosynthesis were reduced, while malondialdehyde (MDA) content and antioxidant enzyme activities increased. OIN application improved growth, photosynthesis, and catalase (CAT) activity, with O1 achieving the highest yield. Structural equation modeling indicated that yield improvement in S1 was mainly driven by photosynthetic traits, whereas in S2 it resulted from combined effects of growth, photosynthesis, and CAT activity.
Overall, OIN application mitigates salinity stress effects on maize, with U1O1 optimal for mildly saline soil and O1 optimal for moderately saline soil. These findings provide insights into managing nitrogen forms to improve crop productivity in saline environments.
土壤盐渍化是干旱和半干旱地区作物生产的主要限制因素。有机氮和无机氮联合施用（OIN）已被认为是提高盐渍土生产力的有效策略。然而，与光合作用和抗氧化反应相关的产量提高潜在机制仍不清楚。
2018年至2020年在内蒙古河套灌区轻度盐渍土（S1，电导率=0.68 dS m⁻¹）和中度盐渍土（S2，电导率=1.25 dS m⁻¹）上进行了田间试验。设置了六种氮处理：不施氮（CK）、仅施无机氮（U1）以及有机氮替代25%、50%、75%和100%无机氮（U3O1、U1O1、U1O3和O1）。测定了玉米生长、光合参数和抗氧化酶活性。
在S1条件下，OIN显著提高了叶面积指数（LAI）、光合性能、超氧化物歧化酶（SOD）活性和产量，其中U1O1产量最高。在S2条件下，生长和光合作用降低，而丙二醛（MDA）含量和抗氧化酶活性增加。施用OIN改善了生长、光合作用和过氧化氢酶（CAT）活性，O1产量最高。结构方程模型表明，S1条件下产量提高主要由光合性状驱动，而S2条件下则是生长、光合作用和CAT活性共同作用的结果。
总体而言，施用OIN减轻了盐胁迫对玉米的影响，U1O1对轻度盐渍土最佳，O1对中度盐渍土最佳。这些发现为在盐渍环境中通过管理氮形态提高作物生产力提供了见解。
