不同烤烟套作模式对烤烟根际土壤细菌群落特征及烤烟产质量的影响

[目的]探讨云南不同烤烟套作模式对烤烟根际土壤细菌群落特征及烤烟产质量的影响,为优化当地烤烟种植模式提供科学依据.[方法]采用单因素随机区组试验,设烤烟套种白菜(T1)、烤烟套种结球甘蓝(T2)和烤烟套种豌豆(T3)3个处理,以烤烟单作为对照(CK),采用16S rRNA测序技术分析不同套作模式烤烟根际土壤细菌群落结构及多样性差异,同时进行土壤优势细菌与土壤理化性状的相关性分析及不同处理的烤烟产质量分析.[结果]16S rRNA测序结果表明,套作处理整体可提高烤烟根际土壤细菌多样性指数,Shannon指数排序为T3>T2>T1>CK,Simpson指数排序为T3=T2>T1>CK,Chao1和ACE指数排序为T3>T2>CK>T1.各处理烤烟根际土壤细菌主要分布在10个菌门,其中变形菌门(Proteobacteria)的丰度最高,占各样本总有效序列的50%以上.CK处理根际土壤中副球菌属(Paracocccus)、假单胞菌属(Pseudomonas)、马赛菌属(Massilia)、Psychrobacter属、短波单胞菌属(Brevundimonas)和产卟啉杆菌属(Porphyrobacter)丰度较套作处理显著提高(P<0.05,下同),而鞘氨醇单胞菌属(Sphingomonas)和Haliangium属丰度显著降低;烤烟套作处理显著降低了烤烟根际土壤pH,同时提高了烤烟根际土壤的主要养分含量.相关性分析结果表明,CK处理土壤中丰度较高的假单胞菌属(Pseudomonas)与土壤总有机碳含量呈显著负相关,丰度较低的鞘氨醇单胞菌属(Sphingomonas)和Haliangium属与土壤总有机碳含量呈显著正相关.不同套作处理可不同程度地提高烤烟产质量,产值、产量、均价和上等烟比例排序均为T3>T2>T1>CK,以T3处理与优质烟叶标准最接近,化学成分最协调.[结论]烤烟套种白菜、结球甘蓝和豌豆较烤烟单作可明显提高烤烟根际细菌多样性,不同程度地降低土壤中潜在致病菌丰度,提高烤烟产质量,其中以套种豌豆的效果最佳.

Effects of different intercropping patterns on rhizosphere soil bacteria colony characteristics and flue-cured tobacco yield and quality

[Objective]Effects of different intercropping patterns on rhizosphere soil bacteria colony characteristics and flue-cured tobacco yield and quality were studied in order to provide reference for improving local tobacco planting pattern.[Method]Single-factor randomized block experiment was adopted and tobacco-Chinese cabbage intercropping(T1), toba-cco-common head cabbage intercropping(T2), tobacco-pea intercropping(T3) were set, and tobacco single planting was taken as control(CK). Rhizosphere bacteria colony characteristics and diversity index were analyzed by 16S rRNA sequen-cing. Correlation between dominant bacteria and soil physical and chemical properties , yield and quality of flue-cured to-bacco in different treatments were also studied. [Result]16S rRNA sequencing showed that intercropping could increase di-versity indexes of rhizosphere soil bacteria. Shannon index ranking was as follows:T3>T2>T1>CK, Simpson index ranking was: T3=T2>T1>CK, Chaol index and ACE index ranking were the same: T3>T2>CK>T1. Rhizosphere soil bacteria in different treatments fell into ten phyla, and abundance of Proteobacteria was the highest and consisted of over 50% total effective sequences. In CK, abundance of Paracocccus,Pseudomonas,Massilia,Psychrobacter,Brevundimonas and Porphy-robacter in rhizosphere soil significantly increased compared with those in intercropping treatments (P<0.05, the same be-low), but abundance of Sphingomonas and Haliangium significantly decreased. Intercropping treatments significantly de-creased pH value but increased major nutrient contents of rhizosphere soil. Correlation analysis showed that:in CK, there was significant negative correlation between high-abundance Pseudomonas and total soil organic carbon content , and significant positive correlation between low-abundance Sphingomonas and Haliangium and soil total organic carbon content. Different intercropping treatments could increase tobacco quality to various extents, and the ranks of output value, yield, average price and proportion of first-class tobacco were the same:T3>T2>T1>CK. The tobacco quality in T3 was the closest to high-quality tobacco standard with the most balanced chemical components. [Conclusion]Tobacco intercropping Chinese cabbage, common head cabbage and pea can obviously increase diversity of rhizosphere soil bacteria, lower abundance of potential pathogenic bacteria in soil to certain extent, and improve tobacco quality. Tobacco-pea intercropping has the optimal effects.