State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China.
Institute for Global Food Security, Queen's University Belfast, David Keir Building, Malone Road, Belfast BT9 5BN, Northern Ireland.
Environ Sci Technol. 2021 Oct 5;55(19):13082-13092. doi: 10.1021/acs.est.1c05358. Epub 2021 Sep 23.
Resolving chemical/biological drivers of P behavior around lowland/flooded rice roots remains a challenge because of the heterogeneity of the plant-soil interactions, compounded by sampling and analytical constraints. High-spatial-resolution (sub-mm) visualization enables these processes to be isolated, characterized, and deciphered. Here, three advanced soil imaging systems, diffusive gradients in thin-film technique coupled with laser ablation-ICPMS (DGT-LA-ICPMS), O planar optode, and soil zymography, were integrated. This trio of approaches was then applied to a rice life cycle study to quantify solute-P supply, through two dimensions, , and low-disturbance high-resolution (HR) chemical imaging. This allowed mechanisms of P release to be delineated by O, Fe, and phosphatase activity mapping at the same scale. HR-DGT revealed P depletion around both living and dead rice roots but with highly spatially variable Fe/P ratios (∼0.2-12.0) which aligned with changing redox conditions and root activities. Partnering of HR-DGT and soil zymography revealed concurrent P depletion and phosphatase hotspots in the rhizosphere and detritusphere zones (Mantel: 0.610-0.810, < 0.01). This close affinity between these responses (Pearson correlation: -0.265 to -0.660, < 0.01) cross-validates the measurements and reaffirms that P depletion stimulates phosphatase activity and P mineralization. The μ-scale biogeochemical landscape of rice rhizospheres and detritusphere, as documented here, needs greater consideration when implementing interventions to improve sustainable P nutrition.
解决低地/淹没水稻根际 P 行为的化学/生物学驱动因素仍然是一个挑战，因为植物-土壤相互作用具有异质性，加上采样和分析的限制。高空间分辨率（亚毫米）可视化使这些过程能够被隔离、表征和破译。在这里，三种先进的土壤成像系统，即薄膜扩散梯度技术与激光烧蚀-ICPMS（DGT-LA-ICPMS）、O 平面光导和土壤酶谱技术相结合。然后，将这三种方法应用于水稻生命周期研究中，通过二维和低干扰高分辨率（HR）化学成像来定量溶质 P 的供应。这使得通过 O、Fe 和磷酸酶活性映射可以在同一尺度上划分 P 释放的机制。HR-DGT 揭示了活的和死的水稻根周围的 P 耗尽，但具有高度空间可变的 Fe/P 比（约 0.2-12.0），这与不断变化的氧化还原条件和根活性一致。HR-DGT 与土壤酶谱的结合揭示了根际和碎屑区（Mantel：0.610-0.810，<0.01）同时存在 P 耗尽和磷酸酶热点。这些响应之间的密切关联（Pearson 相关系数：-0.265 至-0.660，<0.01）相互验证了测量结果，并再次证实 P 耗尽刺激了磷酸酶活性和 P 矿化。如本文所述，水稻根际和碎屑区的 μ 尺度生物地球化学景观在实施改善可持续 P 营养的干预措施时需要更多的考虑。
