硝化抑制剂对微生物驱动小麦根际氮素转化及氮素吸收利用的调控机制

The relatively high nitrification rate in upland soil leads to the lower nitrogen use efficiency (NUE). Nitrification inhibitors are effective in inhibiting soil nitrification and increasing NUE. Application of nitrification inhibitor together with nitrogen fertilizer is therefore becoming a beneficial nitrogen management strategy in field. The rhizosphere, the gateway of crops for water and nutrients uptake from soil, has played a vital role in regulating the transformation and uptake of nitrogen. However, in upland soil, the effects of nitrification inhibitors on nitrogen transformation and related microorganisms, as well as nitrogen uptake and utilization in crops rhizosphere still remain poorly understood. In this project, by using the typical fluvo-aquic soil, which is the most typical soil in the North China Plain, wheat and the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) will be taken as the research subjects to conduct pot experiments, combining 15N tracing, quantitative real time PCR and metagenomic sequencing techniques, the current project aims to: (i) investigate the effects of DMPP on the nitrogen transformation in wheat rhizosphere at different growth stages, (ii) reveal the microbial mechanism of DMPP regulating the nitrogen transformation in wheat rhizosphere, and (iii) to clarify the physiological and molecular mechanism of DMPP influencing nitrogen uptake and utilization of wheat. The outcomes evolved from this project will provide deep insight into the microbial mechanisms of nitrification inhibitors under the crop-soil-microbes system, and theoretical guidance for designing practical and feasible nitrogen management to improve nitrogen nutrition of wheat in upland soil.

旱地农田土壤中相对强烈的硝化作用会导致氮素利用率偏低。硝化抑制剂与氮素配施能有效抑制土壤硝化作用、提高氮肥利用率，是一种有效的田间氮素管理策略。根际在作物氮转化及养分吸收利用方面具有重要作用，但在旱地农田土壤中，硝化抑制剂对作物根际氮转化和相关微生物以及对作物氮素吸收利用的影响仍不明确。华北平原农田以旱地为主，本项目拟以小麦和硝化抑制剂3,4-二甲基吡唑磷酸盐（DMPP）为研究对象进行盆栽试验，结合稳定性同位素示踪、荧光定量PCR和宏基因组测序等技术，研究：1）旱地农田土壤中硝化抑制剂对小麦不同生育期根际氮素转化过程的影响；2）硝化抑制剂影响影响小麦根际氮素转化过程的微生物机制；3）硝化抑制剂影响小麦氮素吸收利用的生理分子机理。研究结果有助于加深在作物-土壤-微生物体系下对于硝化抑制剂作用机理的认知，为改善小麦氮素营养、设计切实可行的旱地农田田间氮素管理策略提供科学依据。

旱地农田土壤中相对强烈的硝化作用会导致氮素利用率偏低。硝化抑制剂能有效抑制土壤硝化作用、提高氮肥利用率，是一种有效的田间氮素管理策略。根际在作物氮转化及养分吸收利用方面具有重要作用，但在旱地农田土壤中，硝化抑制剂对作物根际氮转化和相关微生物以及对作物氮素吸收利用的影响仍不明确。华北平原农田以旱地为主，本项目以小麦/玉米和硝化抑制剂3,4-二甲基吡唑磷酸盐（DMPP）为研究对象，配施不同类型碳源进行了盆栽试验，结合稳定同位素示踪和宏基因组测序等技术，研究发现，硝化抑制剂配施不同碳源，影响了土壤中微量元素（Fe/Cu/Zn/Mn）的含量。施用DMPP，提高了小麦和玉米地上部/地下部的生物量，与不添加碳源处理相比，添加葡萄糖降低了小麦生物量，施用生物炭则增加了小麦生物量。添加葡萄糖后，显著降低了植物从施入肥料中获取的氮素比例（Ndff, 10%~15%）。施用抑制剂降低了小麦植株和玉米地下部来自肥料N的比例（Ndfs），增加了从土壤中获取的N的比例。施用DMPP提高了小麦和玉米的NUE。但是添加葡萄糖处理的NUE则显著低于不添加碳源和添加生物炭处理。施用DMPP处理（DP）降低了氮素损失。施用硝化抑制剂DMPP和添加不同类型碳源，均显著改变了微生物的群落结构，添加葡萄糖处理的微生物群落结构也显著有别于不添加葡萄糖的处理。本项目探究了：1）旱地农田土壤中硝化抑制剂配施不同碳源对小麦/玉米关键生育期根际氮素转化过程的影响；2）硝化抑制剂配施不同碳源影响影响小麦/玉米根际氮素转化过程的微生物机制；3）硝化抑制剂配施不同碳源影响小麦/玉米氮素吸收利用的机理。研究结果有助于加深在作物-土壤-微生物体系下对于硝化抑制剂作用机理的认知，为改善小麦/玉米氮素营养、设计切实可行的旱地农田田间氮素管理策略提供科学依据。