Abstract: In order to determine the effects of alfalfa post-harvest rotation on soil bacterial community in arid desert oasis,an experiment was set up with the following five crop rotation treatments:(Ⅰ)control (CK) with six-year-old alfalfa;(Ⅱ) 5-year-old alfalfa-1-year-old wheat (T₁);(Ⅲ) 5-year-old alfalfa-1-year-old canola (T₂);(Ⅳ) 5-year-old alfalfa-1-year-old sunflower (T₃);and (Ⅴ) 5-year-old alfalfa-1-year-old corn (T₄). The characteristics of soil bacteria in different treatments were analyzed by high-throughput sequencing (Illumina HiSeq). The results showed that T₁and T₂ treatments significantly increased soil microbial biomass carbon content. T₄treatment significantly increased soil microbial biomass nitrogen content. T₃ and T₄ treatments significantly improved soil respiration. Soil urease,alkaline phosphatase,catalase,sucrase activities in T₁,T₂,T₃,and T₄ treatments were 1.44,1.13,1.36,and 1.54 times,1.53,7.78,4.25,and 7.28 times,1.09,1.28,1.14,and 1.06 times,1.11,1.38,1.14,and 1.74 times higher than that in CK treatment,respectively. Proteobacteria,Acidobacteria,Gemmatimonadetes,and Bacteroidetes were the four dominant bacteria in different treatments,accounting for 82.67% of all bacteria. Compared with CK,Proteobacteria,Gemmatimonadetes,and Actinobacteria decreased while Acidobacteria increased after different crop rotations. The abundance index (ACE and Chao1) of T₁ and T₂ treatments were significantly higher than CK (P<0.05). In conclusion,different crop rotations increased soil enzyme activities,stabilized bacterial community structure and improved soil productivity.

Key words: Alfalfa, Rotation, Bacterial community structure, High throughtput sequencing, Arid desert oasis

摘要： 为阐明荒漠灌区苜蓿（Medicago sativa）后茬轮作不同作物对土壤细菌群落的影响，本研究以6年生苜蓿地为对照（CK），以5年生苜蓿地翻耕灭茬分别种植1年小麦（Triticum aestivum）（T₁）、油菜（Brassica chinensis）（T₂）、葵花（Helianthus annuus）（T₃）、玉米（Zea mays）（T₄）为处理，采用高通量测序技术，分析不同处理下土壤细菌群落的变化特征。结果表明，T₁，T₂微生物量碳含量显著大于CK，T₄微生物量氮含量显著高于CK（P<0.05）；T₃，T₄土壤呼吸显著大于CK（P<0.05）；T₁，T₂，T₃，T₄脲酶、碱性磷酸酶、过氧化氢酶、蔗糖酶活性分别是CK的1.44，1.13，1.36，1.54倍，1.53，7.78，4.25，7.28倍，1.09，1.28，1.14，1.06倍，1.11，1.38，1.14，1.74倍；与CK相比，轮茬后变形菌门、放线菌门、芽单胞菌门相对丰富呈降低、而酸杆菌门相对丰富呈增加趋势，这4个菌门为不同处理的优势菌门，占所有菌门的82.67%；T₁，T₂土壤细菌群落丰富度指数（Chao1和ACE）均显著高于CK（P<0.05）。综上，荒漠灌区轮茬较苜蓿连作更有助于提高土壤酶活性，稳定细菌群落结构，提高土地生产力。

关键词: 苜蓿, 轮茬, 细菌群落结构, 高通量测序, 荒漠灌区