间隙灌溉和控释肥施用对稻田土壤产甲烷微生物的影响

间隙灌溉和控释肥施用影响稻田CH_4的产生和排放,然而其微生物机理尚不清楚。本研究通过采集稻季田间原位试验新鲜土样,采用核酸定量技术(qPCR)和末端限制性片段长度多态性(T-RFLP)技术,研究间隙灌溉和控释肥施用对稻田土壤产甲烷微生物群落丰度和结构的影响。结果表明,稻季CH_4排放量与古菌、产甲烷菌(mcr A基因)和甲烷氧化菌(pmo A基因)数量均呈极显著正相关关系(P0.01),而与细菌数量无显著相关性。间隙灌溉显著影响产甲烷菌和甲烷氧化菌数量的季节变化,其中烤田抑制产甲烷菌生长,而对甲烷氧化菌数量没有显著影响。与尿素相比,施用控释肥增加了稻田土壤细菌、古菌和产甲烷菌数量,降低了甲烷氧化菌数量。土壤古菌群落的优势T-RFs片段为184bp和391bp,其中184bp片段的相对丰度随着间隙灌溉的进行由45%~55%降低到23%~30%;而391bp片段则相反,其相对丰度由12%~18%增加到23%~26%。典型相关性分析(CCA)表明间隙灌溉显著影响土壤古菌群落结构(P0.001),而控释肥施用对土壤古菌群落结构没有明显影响。

Effect of Intermittent Irrigation and Controlled-release Fertilizer on Methanogenic Microbial Communities in Paddy Soil

Intermittent irrigation and controlled-release fertilizer (CRF) application affect CH₄ production and emission in paddy soil, but the underlying microbial mechanism remains poorly understood. Fresh soils were sampled through the rice growing season in a field experiment to elucidate the effect of intermittent irrigation and CRF application on the methanogenic microbial communities using the methods Quantitative Real-time PCR (qPCR) and Terminal restriction fragment length polymorphism (T-RFLP). CH₄ emission was positively correlated with the abundances of archaea, methanogens (mcrA gene) and methanotrophs (pmoA gene) (P <0.01), while no significant relationship was found with the abundances of bacteria. Intermittent irrigation significantly influenced the seasonal variation of abundances of methanogens and methanotrophs. Mid-season aeration (MSA) strongly decreased the abundances of methanogens, while no significant effect was detected on abundances of methanotrophs. Compared with urea, CRF addition increased the abundances of bacteria, archaea and methanogens, while decreased the abundances of methanotrophs. The archaeal community was dominated by T-RFs of 184bp and 391bp. Along the intermittent irrigation, the relative abundance of 184bp decreased from 45% - 55% to 23% - 30%, while that of 391bp increased from 12%-18% to 23%-26%. The canonical correspondence analysis (CCA) showed that intermittent irrigation significantly affected the archaeal communities (P <0.001) rather than the different fertilization.