• ISSN 1008-505X
  • CN 11-3996/S
ZHANG Ling-ling, LI Qing-mei, JIA Meng-yuan, ZHANG Yan-jun, ZHAO Jian-ning, YANG Dian-lin, WANG Hua-ling, WANG Hui. Effects of cover crops on gene abundance and community structure of soil ammonia-oxidizing microorganism in a kiwifruit orchard[J]. Journal of Plant Nutrition and Fertilizers, 2021, 27(3): 417-428. DOI: 10.11674/zwyf.20361
Citation: ZHANG Ling-ling, LI Qing-mei, JIA Meng-yuan, ZHANG Yan-jun, ZHAO Jian-ning, YANG Dian-lin, WANG Hua-ling, WANG Hui. Effects of cover crops on gene abundance and community structure of soil ammonia-oxidizing microorganism in a kiwifruit orchard[J]. Journal of Plant Nutrition and Fertilizers, 2021, 27(3): 417-428. DOI: 10.11674/zwyf.20361

Effects of cover crops on gene abundance and community structure of soil ammonia-oxidizing microorganism in a kiwifruit orchard

  • Objectives Planting of cover crops between fruit tree rows can improve soil physicochemical properties, and change the structure of ammonia-oxidizing microorganism community in the process of the nitrogen cycle. Here, we analyzed the effects of different cover crop treatments on soil ammonia-oxidizing microorganisms in a kiwifruit orchard, and examined its relationship with soil nitrification.
    Methods Soil samples were collected from a five-year kiwifruit orchard where cover crops experiment was set up including four kinds of cover crops white clover (Trifolium repens L, W), hairy vetch (Vicia Villosa Roth, V), ryegrass (Lolium perenne L, R) and tall fescue (Festuca elata Keng ex E. Alexeev, F). The treatments included single cover crop (W), two cover crops (WR), three cover crops (WRV), four cover crops (WRVF) and cleaning tillage (CK). Q-PCR, T-RFLP and cloning and sequencing were employed to analyze the changes in gene abundance, community diversity and structure of AOA and AOB of the different cover crop treatments.
    Results There was no significant difference in the above-ground biomass of the four cover crop treatments. However, soil water content, ammonium and nitrate nitrogen (P < 0.05) increased while soil pH decreased in the WR treatment. Similarly, there was no significant difference in soil physicochemical properties among the other three cover crop treatments. Compared with CK, the abundance of the AOA-amoA gene in W (P < 0.05) was increased by 2.85%, and the abundance of the AOB-amoA gene in W and WR was significantly increased by 4.95% and 6.42%, respectively. The proportion of T-RFs representing AOA varied among the treatmenta but did not cause significant changes in AOA community structure. AOB represented by T-RFs changed, and the AOB community structure might change. AOA diversity index significantly decreased in WR, AOA evenness index decreased in WR and WRVF, while AOB diversity index increased in WRV and WRVF. Under the four treatments, the dominant soil bacteria of the AOA group were Nitrososphaera (44.2%) and Nitrosotalea (45.8%), and those of AOB group were Nitrosospira (96.98%) and Nitrosomonas (3.02%). Pearson correlation analysis and redundancy analysis showed that soil pH, water content, ammonium nitrogen and nitrate nitrogen were the main factors affecting soil ammonia-oxidizing microorganism abundance and community structure.
    Conclusions Soil pH, soil water, ammonium and nitrate nitrogen content are the main environmental factors affecting the community structure and abundance of ammonia-oxidizing microorganisms. White clover and ryegrass mixed cropping system significantly increases soil moisture content, ammonium and nitrate nitrogen content but decreases soil pH. However, the differences in soil properties lead to increased diversity of microorganism, but not sufficient enough to cause a variation in the microbial structure.
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