水稻生育期对不同施肥条件下黄泥田土壤无机氮及细菌群落的影响

Effect of the phenological stage of rice growth on soil-soluble inorganic nitrogen and bacterial communities in a yellow clayey soil under different fertilization patterns

为揭示不同施肥条件下水稻生育期黄泥田土壤细菌群落的动态变化及对可溶性无机氮的影响,以33年不同施肥处理(不施肥CK、单施无机肥NPK、无机肥配施牛粪NPKM和无机肥配施秸秆NPKS)的黄泥田为研究对象,采用实时荧光定量PCR和高通量测序等技术分析水稻幼苗期、分蘖期、拔节期、扬花期和成熟期的黄泥田耕层土壤细菌数量、群落组成和结构.结果显示,黄泥田可溶性无机氮以铵态氮为主,含量为6.01-30.93 mg/kg,占可溶性无机氮总量的95%以上.细菌16S rRNA基因拷贝数为3.03×10^7-14.33×10^7/g干土.土壤优势细菌群落为变形菌门、绿弯菌门、放线菌门和酸杆菌门.偏最小二乘法判别分析表明,不同施肥处理细菌群落差异以拔节期最为明显;不同生育期细菌群落差异以无机有机肥配施处理最为明显.多元方差分析表明,水稻生育期可以解释细菌群落结构59.79%的变异,施肥处理可以解释细菌群落结构10.44%的变异,土壤铵态氮与细菌16S rRNA基因拷贝数呈显著正相关(P<0.05).本研究表明土壤细菌群落与土壤铵态氮存在一定的相关性,且水稻不同生育期引起的土壤细菌群落结构差异比不同施肥处理引起的细菌群落结构差异更为明显.(图3表4参26)

The aim of this study was to reveal the dynamics of soil bacterial communities and their effects on the levels of soil-soluble inorganic nitrogen in paddy soil during the growth period of rice under different fertilization patterns.A yellow clayey paddy soil in the Fujian province with 33 years’worth of different fertilization treatments including control(CK),chemical fertilizer(NPK),chemical fertilizer combined with cow manure(NPKM),and chemical fertilizer combined with rice straw(NPKS),was used in this study.The abundance and diversity of bacterial species,bacterial community structure,and levels of soil-soluble inorganic nitrogen in the paddy field during the seedling,tilling,booting,flowering and ripening stages were analyzed by real-time quantitative PCR and high-throughput sequencing.The results showed that the concentration of ammonium in the yellow clayey paddy soil ranged from 6.01 to 30.93 mg/kg and was the main source of soluble inorganic nitrogen in the soil.The 16S rRNA gene copy number ranged from 3.03×10^7 to 14.33×10^7 per g of dry soil,which showed that the abundance of soil bacteria varied greatly during the rice growth stages.The dominant bacterial communities in yellow clayey paddy soil were Proteobacteria,Chloroflexi,Actinobacteria,and Acidobacteria.Partial Least Squares Discriminant Analyses(PLS-DA)showed that the booting stage induces great variation in bacteria communities compared with other growth stages of rice.Also,inorganic fertilizers combined with organic fertilizers(NPKS and NPKM)showed great variation in comparison to different treatments.The permutational multivariate analysis of variance(PERMANOVA)results indicated that the rice growth stages accounted for 59.79%of the variation in the structure of the bacterial community while the treatment explained the 10.44%variation in the bacterial community structure.The soil ammonium concentration was positively correlated with the abundance of bacteria(P<0.05).We concluded that the structure of the bacterial community in the soil was related to the concentration of ammonium nitrogen in paddy soil.Differences in the bacterial community structure were more likely to be influenced by the growth stages of rice rather than fertilization patterns.