Roots respond to nitrogen deficiency by altering their physiological and metabolic responses. Soil nitrogen invertase activity and the diversity of nitrifying microorganisms (AOA and AOB) significantly affect the nitrogen cycle in soil. As an important part of root exudates, organic acids can reflect the dynamic changes of plant roots in soil. However, it is not clear how the barren-tolerant genotype plant varieties show their stress resistance through organic acids regulating nitrogen transformation under low nitrogen environment. Here, we selected two Tartary buckwheat varieties: HeiFeng1 (HF, low nitrogen sensitive cultivar) and DiQing (DQ, low nitrogen tolerance cultivar) for a two-year experiment. The urea addition levels of 0, 80, and 160 mg kg⁻¹ soil were respectively set as nitrogen sources, and ozone sterilization experiments were designed to completely remove microbial effects to distinguish the contribution of plant roots and microorganisms to nitrogen invertase and organic acids (400 ml 1 mol L⁻¹ ozone water daily, 0 nitrogen fertilizer, O3). The results showed that malic acid and tartaric acid were the main organic acids secreted by tartary buckwheat. The total amount and richness of organic acids in Diqing were higher than those in Heifeng, and organic acids directly affected the diversity of ammonia-oxidizing microorganisms (AOA and AOB), changed the soil environment by affecting soil water content, and indirectly affected the activity of nitrogen invertase. At the same time, it was found that the increase of nitrogen application rate would increase the proportion of key bacteria such as Nirtrosomonas and Nitrosospira in AOB of tartary buckwheat soil. Finally, Diqing tartary buckwheat was proved to be more suitable for planting in the nitrogen-deficient Loess Plateau, but attention should be paid to the negative effects of AOB and organic acids.

根部通过改变其生理和代谢反应来应对氮缺乏。土壤氮转化酶活性和硝化微生物（AOA和AOB）的多样性显着影响土壤中的氮循环。有机酸作为根系分泌物的重要组成部分，可以反映植物根系在土壤中的动态变化。然而，耐贫瘠基因型植物品种如何在低氮环境下通过有机酸调节氮素转化来表现出抗逆性尚不清楚。在这里，我们选择了两个苦荞品种：黑丰1号（HF，低氮敏感品种）和迪青（DQ，低氮耐受品种）进行了为期两年的试验。尿素添加水平为0、80和160 mg kg ^-1分别以土壤为氮源，设计臭氧灭菌实验，彻底去除微生物影响，区分植物根系和微生物对氮转化酶和有机酸的贡献（400 ml 1 mol L ^-1每日臭氧水，0氮肥，O3)。结果表明，苦荞分泌的主要有机酸为苹果酸和酒石酸。迪庆地区有机酸总量和丰富度均高于黑峰地区，且有机酸直接影响氨氧化微生物（AOA和AOB）的多样性，通过影响土壤含水量改变土壤环境，间接影响其活性氮转化酶。同时发现施氮量的增加会增加亚硝化单胞菌、亚硝化螺菌等关键细菌的比例存在于苦荞土的 AOB 中。最后证明迪庆苦荞更适合在缺氮的黄土高原种植，但应注意AOB和有机酸的负面影响。