Objective  The study analyzed the correlation between the rhizosphere allelochemicals and tobacco economic characteristics and would provide a reference for decreasing the probolem caused by continuous cropping.

  Method  Continuous cropping tobacco from Yunnan Honghe Luxi were used as materials and allelochemicals were detected by GC-MS.

  Result  The results showed that 13 kinds of rhizosphere allelopathy substances were detected in rhizosphere soil of flue-cured tobacco. Three common factors were extracted by factor analysis. The first factor was phenolic acid factor, accounting for 53.752% of the total variance of variables. Myristic acid, belladonna pavilion, margaric acid and linolenic acid positively correlated with each other with high load. The second factor was acid-ester amide factor, accounting for 19.272% of the total variance of the variable. Benzoic acid, vanillin, palmitic acid, erucic acid amide had high positive loads. The third factor was phenolic ester factor, accounting for 11.778% of the total variance of variables. 2,2′-methylene bis -(6-tert-butylp-methylphenol) and dioctyl phthalate had high positive load. The results of simple correlation and canonical correlation showed that the effect of rhizosphere allelochemicals on tobacco economical characters was comprehensive and the first common factor was the main indicator. It behaved that myristic acid, belladonna pavilion, margaric acid and linolenic acid positively correlated with tobacco output value, while they negatively correlated with ration of middle-high grade leaves and weight per leaf class.

  Conclusion  Rhizosphere allelochemicals of tobacco had a bidirectional effect on tobacco. While the positive effects of increasing single leaf weight and output value were higher than decreasing ratio of middle-up class leaves. So it would provide a new thought and method for decreasing continuous cropping obstacle about how to make use of rhizosphere allelochemicals.