Effects of N rhizodeposition on rhizosphere N transformation in clonal ramets of Moso bamboo forest

• Published in: Plant and soil 2024-10, Vol.503 (1-2), p.717-732
• Main Authors: Shi, Man, Yang, Weiwei, Zhang, Junbo, Sun, Jilei, Ji, Hangxiang, Li, Quan, Cao, Tingting, Wang, Zhikang, Zhang, Chao, Song, Xinzhang
• Format: Article
• Language: English
• Subjects: Abundance; Agriculture; Ammonia; Ammonia-oxidizing bacteria; Bamboo; Biomedical and Life Sciences; Denitrification; Ecology; Genes; Genetic transformation; Life Sciences; Mineralization; Nitrification; Oxidation; Phyllostachys edulis; Plant Physiology; Plant Sciences; Research Article; Rhizosphere; Soil layers; Soil Science & Conservation; Soils
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-024-06615-9

Aims N rhizodeposition plays a vital role in regulating rhizosphere soil N dynamics. However, its effects on the rhizosphere soil N cycle in clonal plants and the underlying mechanism remain unclear. Methods 15 N solutions with different concentrations were injected into young or connected mature ramets of Moso bamboo ( Phyllostachys edulis ), respectively, in the field, to explore the response of rhizosphere N transformation to N rhizodeposition. Results 15 N injection increased the 15 N abundance in the rhizosphere soil of both young and mature ramets, with higher 15 N abundance in 20–40-cm layer than that in 0–20-cm layer. Functional genes involved in nitrification and denitrification in the rhizosphere were upregulated when young ramets received low- and medium-N solutions. However, the genes showed diverse responses to high-N treatment in young ramets, with increased abundances of ammonia-oxidizing bacteria and decreased levels of ammonia-oxidizing archaea, comammox, and denitrifiers. In contrast, the functional genes involved in denitrification in the 20–40-cm layer of rhizosphere soil were upregulated by high-N treatment in mature ramets. Additionally, partial-least-squares path modeling revealed 15 N abundance in the soil indirectly affected N mineralization, N mineralization directly affected nitrification, and nitrification directly affected denitrification in a positive manner. Conclusion The variations of N rhizodeposition and transformation process in both connected ramets is highly consistent in responding to different N treatments, but the nitrifiers and denitrifiers in the deeper rhizosphere soil were more sensitive to N rhizodeposits than those in the upper rhizosphere soil.