蚯蚓和菌根协同提高酸化耕地玉米氮素利用效率的作用机理

The acidification of cropland soil caused by excessive application of chemical nitrogen fertilizer is one of the increasingly prominent problems in the intensive agricultural production in China. Earthworms function as ecosystem engineers and accelerate nutrient cycling in the soil-plant system by burrowing, casting, mixing, and regulating the soil microbial community. Mycorrhizal symbioses contribute to plant growth and plant protection against various environmental stresses, such as drought, salinity and acidity. The cooperation between earthworm and mycorrhiza on improving soil nitrogen transformation and increasing nitrogen use efficiency of maize in acidified soil will be studied from these three sections: (1) the cooperative effect of earthworm and mycorrhiza on soil H+ production and nitrogen availability, which could improve the maize growth in acidified farmland, will be determined by testing soil nutrients, soil microbal biomass, soil enzyme activity and plant biological changes. (2) The effect of earthworm and mycorrhiza on soil nitrogen transformation and plant uptake driven by soil N cycling bacteria will be studied by determining of its origin using stable isotopes (15N) and the express of N transporter gene, which can explain the interactive effect of earthworm and mycorrhiza on maize N use in acidified soil. .(3) Illumina MiSeq method will be used to determine the cooperative effect of earthworm and mycorrhiza on the regulation of soil microorganisms, which can drive the plant nutrient uptakes and physiological resistance to soil acidity in the in the acidified farmland. Our results will give useful information for understanding the soil acidification and the ecological function of soil biota.

过量施用化学氮肥造成的农田土壤酸化是中国集约化农业生产中日益突显的问题之一。本研究利用蚯蚓调控土壤微生物改良土壤-植物体系养分循环和菌根提高植物的抗逆性，研究蚯蚓和菌根促进土壤氮素的生物转化，进而提高酸化土壤中玉米氮素利用效率的生态过程，具体如下：（1）通过测定土壤养分，微生物数量和酶活性及玉米生长指标，揭示蚯蚓和菌根相互作用影响农田土壤产酸过程的物质循环-氮素有效性的耦合过程的生态机理；（2）通过15N同位素标记法结合荧光定量植物氮转运蛋白基因的表达，揭示蚯蚓和菌根相互作用调控土壤氮功能微生物，进而促进酸化土壤氮矿化和提高玉米氮吸收的作用机制；（3）通过Illumina MiSeq高通量测序技术测定土壤微生物群落变化，测定植物抗氧化酶和抗逆激素，揭示田间原位接种蚯蚓和菌根调控微生物群落，促进玉米养分吸收，提高其生理耐酸性的生态过程。研究结果对于揭示酸化耕地土壤演变规律和土壤生物的生态功能

长期肥料过量施用加速中性尤其弱酸性农田土壤酸化已成为中国耕地质量退化的凸显问题。作为土壤食物网重要组成的土壤生物在酸化耕地改良中具有很大作用潜力。本研究利用蚯蚓调控土壤微生物改良土壤-植物体系养分循环和菌根提高植物的抗逆性，研究了蚯蚓和菌根促进土壤氮素的生物转化，进而提高酸化土壤中玉米氮素利用效率的生态过程。本项目主要研究了1)蚯蚓和菌根相互作用影响农田土壤产酸过程的物质循环-氮素有效性的耦合过程;2)蚯蚯蚓和菌根相互作用驱动酸化土壤-植物体系中氮素转化和吸收的生态过程与机理;3)运用分子生物学技术研究了田间原位接种蚯蚓和菌根调控微生物群落，提高玉米耐酸性的生态过程。研究结果证实蚯蚓菌根互作效应可以显著提高酸性土壤氮素有效性，显著促进玉米养分吸收和生长。其中，菌根主要提高玉米对硝态氮利用，蚯蚓主要增加铵态氮肥的偏生产力，蚯蚓和菌根真菌相互作用协同调控土壤微生物群落，促进玉米养分吸收，进而提高玉米产量。结合田间试验验证了生物改良措施对提高酸性土壤作物产量的应用效果，为提高酸性农田化学氮肥利用效率提供了新思路，并进一步揭示了不同生态位土壤生物驱动土壤-植物体系氮素生物小循环的生态过程。研究结果对农田酸化治理和作物生产具有重要的指导和实践价值，有利于促进农业可持续发展和改善农田生态环境。