Effects of continuous application of different nitrogen rates on fungal community structure in potato rhizosphere in semi\|arid area of Gansu Province
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DOI:10.7606/j.issn.1000-7601.2020.01.07
Key Words: excessive nitrogen fertilizer  potato  fungal community structure in rhizosphere  community diversity  soil\|borne disease pathogens
Author NameAffiliation
DENG Delei College of Resources and Environmental Sciences /Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Engineering Research Center of Livestock and Poultry Waste Resource Utilization in Gansu Province, Lanzhou, Gansu 730070, China 
LUO Chaoyue College of Resources and Environmental Sciences /Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Engineering Research Center of Livestock and Poultry Waste Resource Utilization in Gansu Province, Lanzhou, Gansu 730070, China 
QIU Huizhen College of Resources and Environmental Sciences /Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Engineering Research Center of Livestock and Poultry Waste Resource Utilization in Gansu Province, Lanzhou, Gansu 730070, China 
ZHANG Jian College of Resources and Environmental Sciences /Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Engineering Research Center of Livestock and Poultry Waste Resource Utilization in Gansu Province, Lanzhou, Gansu 730070, China 
ZHANG Chunhong College of Resources and Environmental Sciences /Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Engineering Research Center of Livestock and Poultry Waste Resource Utilization in Gansu Province, Lanzhou, Gansu 730070, China 
FU Xiao College of Resources and Environmental Sciences /Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Engineering Research Center of Livestock and Poultry Waste Resource Utilization in Gansu Province, Lanzhou, Gansu 730070, China 
SHEN Qirong College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China 
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Abstract:
      In view of the imbalance of soil microbial community structure and the decline of diversity caused by excessive application of nitrogen (N) fertilizer in potato production, a positioned field experiment of different N application rates (N0: no N application, control, N75: 75 kg·hm-2, N150: 150 kg·hm-2, N225: 225 kg·hm-2, N300: 300 kg·hm-2, and N375: 375 kg·hm-2) was conducted in 2013. Rhizosphere soil was collected during potato ripening period for 7 years. Molecular biological sequencing methods, Illumina PE250, was used to study the effects of different N levels on the rhizosphere fungi community structure of potato in semi\|arid areas for 5 consecutive years. The species composition of the potato rhizosphere fungi community was significantly affected by different N application rates. Ascomycota, Mucoromycota, and Basidiomycota were the three dominant fungi (relative abundance >1.0%). The relative abundance of Ascomycota was the largest, accounting for 75.48%~83.95% of the total sequence. The dominant species were Plectosphaerella (29.92%) and Fusarium (13.54%). The relative abundance of Fusarium, the pathogens of potato dry rot, and Fusarium wilt, increased with the increase in N application. Alpha diversity of potato rhizosphere fungi decreased with the increase in N application. Over\|application of N for 5 years resulted in a significant increase of NO-3-N content in 0~20 cm topsoil. The NO-3-N content in N375 treatment was 3.76 times higher than that in N0 treatment. Over\|application of N for 5 years also significantly reduced the pH value and available phosphorus content in rhizosphere. N375 treatment decreased 0.17 units and 32.10%, respectively, compared with N0 treatment. RDA and correlation analysis showed that soil nitrate N content was the main factor affecting the changes in fungal community structure in potato rhizosphere (F=1.571, P=0.043*). Continuous large\|scale application of N fertilizer significantly reduced potato tuber yield: after 5 years of continuous N application, due to the accumulation of NO-3-N in soil profile, the maximum yield fertilization decreased from N225 in 2013-2014 to N75, and other N treatments reduced the yield by 3.46%, 22.81%, 26.05% and 25.32%, respectively, compared with N75. Long\|term excessive N application resulted in a large accumulation of nitrate N in potato rhizosphere, which led to a decrease in pH, thus reducing the diversity of rhizosphere fungi. At the same time, excessive nitrogen application increased the relative abundance of soil fungal pathogens in the rhizosphere, which was not conducive to soil health and improving potato yield.