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Chinese Journal of Applied Ecology ›› 2025, Vol. 36 ›› Issue (10): 2929-2935.doi: 10.13287/j.1001-9332.202510.012

• Special Features of Carbon-Nitrogen Biogeochemical Cycling Processes in Ecosystems (Guest Editors: LIN Yongxin, ZHENG Mianhai, NI Xiangyin) • Previous Articles     Next Articles

Effects of nitrogen application rates on inorganic nitrogen and microbial nitrogen-transformation functional genes in wheat rhizosphere soil of North China Plain

GAO Bingyang1, CHU Xu2, REN Zhijie3, WANG Yang1, HUANG Yufang1, YE Youliang1, YANG Xue1, ZHAO Yanan1*   

  1. 1College of Resources and Environment, Henan Agricultural University, Zhengzhou 450046, China;
    2Pingdingshan Agriculture and Rural Affairs Bureau, Pingdingshan 467000, Henan, China;
    3Institute of Plant Nutrient and Environmental Resources, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
  • Received:2025-01-09 Revised:2025-08-01 Published:2026-05-04

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Abstract: Understanding the response of inorganic nitrogen (N) and microbial N transformation functional genes in the rhizosphere soil of wheat to N application rates can provide theoretical basis for the N optimizing in wheat production. Based on a long-term field experiment with five N application levels [0 (N0), 120 (N120), 180 (N180), 240 (N240), 360 (N360) kg·hm-2] conducted on the North China Plain with two wheat varieties, Huayu 198 (HY198) and Xinong 979 (XN979), we investigated the effects of N application rates on inorganic N content and the abundance of microbial functional genes (amoA, nirK, nirS, nosZ) related to nitrification and denitrification in rhizosphere soil. The results showed that continuous N application for eight years increased soil ammonium and nitrate content, both of which increased significantly with increasing N application rates by 54.9%-274.2% and 110.3%-614.3% respectively compared to N0. At the same N application, the microbial functional gene abundances of amoA, nirK, and nirS in rhizosphere soil of XN 979 was significantly higher than that of HY 198, while the abundance of nosZ was significantly lower for HY 198. For the nitrification functional genes, the amoA gene abundance of XN 979 was lowest at N120, decreasing by 28.8%, whereas the lowest value for HY 198 occurred at N180, decreasing by 46.9% compared to N0. The amoA gene abundance of ammonia-oxidizing bacteria (AOB) in both cultivars increased significantly with increasing N levels, showing growth rates of 127.4%-362.7% for HY198 and 26.5%-417.9% for XN 979 compare with N0. For denitrification functional genes, the nirK, nirS, and nosZ gene abundances were highest for XN 979 at N240, while in HY 198, the nirK gene abundance was significantly lower at N360 compared to other N levels, and the lowest values for nirS and nosZ occurred at N180. There was significant positive correlation between AOB amoA gene abundance and NH4+-N and NO3--N contents, indicating that AOB was more sensitive to N application. Overall, long-term N application significantly enhanced rhizosphere soil NH4+-N and NO3--N contents, which in turn regulated the abundance of microbial functional genes in nitrification and denitrification.

Key words: nitrogen fertilizer application, wheat cultivar, nitrification function genes, denitrification function genes, inorganic nitrogen