长期施肥对红壤性水稻土细菌群落结构和数量的影响

 【目的】通过对土壤细菌数量和多样性的研究，揭示长期不同施肥制度对土壤微生物生态的影响规律，为中国稻田土壤科学施肥、维护健康土壤微生物生态系统及农业可持续发展等方面提供重要理论和实践依据。【方法】采用末端限制性片段长度多态性分析（T-RFLP）和实时定量（real-time）PCR方法，研究湖南省望城县施用化肥（NPK）和秸秆还田（NPKS）对水稻土细菌群落结构及其多样性和数量的影响。【结果】T-RFLP分析结果表明红壤性水稻土细菌的优势类群为变形菌（150 bp；相对丰度33%—37%）和放线菌（67 bp；相对丰度20%—25%），施肥对土壤细菌群落结构及其多样性产生了显著影响。典范对应分析（CCA)表明不同处理间细菌群落结构差异显著，而土壤pH和有机碳是影响土壤细菌群落结构的主要因子。多样性指数分析（香农指数和均匀度指数）显示秸秆还田处理的土壤细菌多样性最高，施肥处理（氮磷钾配施和秸秆还田）的土壤细菌多样性均高于不施肥处理。通过实时PCR技术定量了3种施肥处理的土壤细菌数量（4.34×1010—10.94×1010 个拷贝16S rDNA每克土），与不施肥相比，施肥后土壤细菌数量增加了50%—100%。【结论】长期施肥对红壤性水稻土细菌群落结构及其多样性和数量均产生了深刻的影响，长期化肥和秸秆还田，土壤质量和土壤肥力提高，土壤细菌种群多样性和数量显著增加。

Response of Abundance and Composition of the Bacterial Community to Long-term Fertilization in Paddy Soils

【Objective】 The impacts of long-term fertilization on soil microbial community structure and abundance were studied to clarify their relationship and provide a theoretical basis for the soil fertility evaluation and management of rice cultivation. 【Method】 The soil samples were collected from long-term fertilization experimental plots receiving no fertilization, chemical fertilization, chemical fertilizer + crop residue incorporation. The terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR analysis were combined to characterize the bacterial community structure and abundance.【Result】Proteobacteria (150 bp; relative abundance 33%—37%) and actinomycetes (67 bp; relative abundance 20%—25%) dominated the bacterial community in paddy soils based on T-RFLP analysis. There was a pronounced difference in the bacterial community composition and diversity responding to the long-term fertilization regimes. CCA results indicated that soil organic carbon (SOC) and pH had the greatest influence on the bacterial community composition. The diversity analysis of Shannon and Evenness Index showed that compared with the unfertilized control, all fertilization treatments significantly increased the bacterial diversity and the harvested residue incorporation also shared the highest. The abundance of bacterial 16S rDNA ranging from 4.34×1010—10.94×1010 copies?g-1soil was determined by real-time PCR, and the amount of 16S rDNA copy number in the fertilization incorporations increased about 50% to 100% of which in unfertilized treatments 【Conclusion】Long-term chemical fertilizer and crop residue incorporation improved soil quality and fertility, and consequently resulted in the shift of the bacterial microecology and promoted the bacterial diversity and abundance.