Drought reinforces the relation between microbial activities and soil respiration but depresses the linkage between microbial activities and soil C and N: Evidence from rhizosphere in rapeseed (Brassica napu)

IF 4.8 2区农林科学 Q1 SOIL SCIENCE

Applied Soil Ecology Pub Date : 2025-05-06 DOI:10.1016/j.apsoil.2025.106148

Qiwen Xu, Bo Zhu, Meichun Duan, Bangyan Liu, Longchang Wang

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Abstract

Soil respiration (SR), the second-largest terrestrial carbon flux, plays a pivotal role in regulating global carbon cycling under climate change. However, drought-induced changes in SR dynamics, particularly in the rhizosphere, remain poorly understood due to methodological limitations. This study employed in situ rhizosphere partitioning (root bag system) and high-frequency diurnal SR monitoring to compare drought responses between two rapeseed (Brassica napus) cultivars with contrasting drought tolerance. Soil organic carbon (SOC), total nitrogen (TN), enzyme index (SEI) and microbial carbon source utilization (MCSU) were assessed in both bulk and rhizosphere area to quantify root-derived effects. The interactions among these factors in the rhizosphere were further explored using structural equation model (SEM). Result showed drought significantly reduced SR, SOC, C:N ratio and MCSU in the rhizosphere for both cultivars (p < 0.05) while had minimal effects on bulk soil. Bulk soil exhibited a 6-h hysteresis in peak SR compared to the rhizosphere. Drought significantly suppressed root-derived SR in the drought-sensitive CY36, while enhancing it in the drought-tolerant YY57. Additionally, rhizosphere effect play a positive role in SR but a negative role in SOC and TN, with this negative effect aggravated by drought. SEM revealed drought depressed the effects of SOC and TN on C:N ratio, SEI and MCSU, while positively reinforced the direct effect of MCSU on SR in the rhizosphere (p < 0.05). Our results highlight the importance of accounting for sensitive changes in the rhizosphere induced by drought when predicting ecosystem carbon and nutrient balance responses to future drought events.

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干旱强化了微生物活动与土壤呼吸的关系，但抑制了微生物活动与土壤碳氮的联系——来自油菜籽根际的证据

土壤呼吸（SR）是第二大陆地碳通量，在气候变化背景下对全球碳循环起着关键的调节作用。然而，由于方法的限制，干旱引起的SR动态变化，特别是根际的SR动态变化仍然知之甚少。本研究采用根际原位分配（根袋系统）和高频日SR监测方法，比较了两个耐旱性不同的油菜品种对干旱的响应。通过对土壤有机碳（SOC）、全氮（TN）、酶指数（SEI）和微生物碳源利用率（MCSU）的评估，量化根源效应。利用结构方程模型（SEM）进一步探讨了这些因子在根际的相互作用。结果表明，干旱显著降低了两个品种根际土壤有机碳、碳氮比和MCSU (p <；0.05)，而对土体的影响极小。与根际土壤相比，块状土壤的SR峰值存在6 h的滞后。干旱显著抑制了干旱敏感型CY36的根系SR，而在耐旱型YY57中则增强了根系SR。根际效应对土壤有机碳和全氮的影响为负，而对土壤有机碳和全氮的影响为负，且干旱加剧了这种负作用。SEM显示干旱抑制了土壤有机碳和全氮对碳氮比、SEI和MCSU的影响，而正增强了MCSU对根际SR的直接影响(p <；0.05)。我们的研究结果强调了在预测生态系统碳和营养平衡对未来干旱事件的响应时，考虑干旱引起的根际敏感变化的重要性。

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来源期刊

Applied Soil Ecology 农林科学-土壤科学

CiteScore

9.70

自引率

4.20%

发文量

363

审稿时长

5.3 months

期刊介绍： Applied Soil Ecology addresses the role of soil organisms and their interactions in relation to: sustainability and productivity, nutrient cycling and other soil processes, the maintenance of soil functions, the impact of human activities on soil ecosystems and bio(techno)logical control of soil-inhabiting pests, diseases and weeds.