title: Research on the nitrogen cycle in rhizosphere of Kandelia obovata under ammonium and nitrate addition.
abstract: The present study investigated nitrogen process in rhizosphere of Kandelia obovata under nitrogen input. Results showed that nitrogen additions significantly increased 4 kinds of enzyme activities (Urease, Nitrate reductase, Nitrite reductase and hydroxylamine reductase). The pH value increased to 7.1 under ammonium addition, but decreased to 6.9 under nitrate addition. Potential Nitrification Intensity (PNI) increased 200-1500% compared with control under ammonium addition, and Potential Denitrification Intensity (PDI) increased more than 200% under nitrate addition. Ten types of organic acids were detected from root exudates, which mainly included oxalic acid, tartaric acid, formic acid, acetic acid, and citric acid. The abundance of 5 kinds of microbial functional groups (nifH, AOA, AOB, nirS, nirK) responded differently. Total nitrogen in organs of K. obovata increased more than 200%. This indicated that nitrogen additions accelerated the transformation of nitrogen directly and stimulated the exudation of root exudates and 5 kinds of genes indirectly.
authors.affiliation: Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361005, PR China.
authors.forename: Bosen
authors.initials: B
authors.lastname: Weng
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Xie
authors.forename: Jinjin
authors.initials: J
authors.lastname: Yang
authors.forename: Jingchun
authors.initials: J
authors.lastname: Liu
authors.forename: Haoliang
authors.initials: H
authors.lastname: Lu
authors.forename: Chongling
authors.initials: C
authors.lastname: Yan
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis; D050901:Nitrate Reductase / Q000378:metabolism; D009566:Nitrates / Q000032:analysis; D009572:Nitrite Reductases / Q000378:metabolism; D058458:Nitrogen Cycle; D010088:Oxidoreductases / Q000378:metabolism; D043982:Rhizophoraceae / Q000502:physiology*; D058441:Rhizosphere
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D010088:Oxidoreductases; D009572:Nitrite Reductases; C021402:hydroxylamine reductase; D050901:Nitrate Reductase
keywords: K. obovata (S.L.) Yong; Low molecular weight organic acids; Nitrogen; Nitrogen related microbial functional groups; Root exudates; Soil enzyme activity