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

ObjectiveEffects 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.MethodSingle-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. Result16S 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. ConclusionTobacco 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.