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Flue-cured tobacco (Nicotiana tabacum L.) is a major cash crop in Yunnan, China, and the yield, chemical components, and their proportions decide the quality of tobacco leaves. To understand the effects of environmental factors (soil and climatic factors) on the yield and quality of flue-cured tobacco and determine the main regulating factors, we selected three flue-cured tobacco cultivars [K326, Yunyan87 (Yun87), and Honghuadajinyuan (Hongda)] grown in the Honghe Tobacco Zone. Indices related to yield and economic traits, chemical component properties, soil physical and chemical properties, and climatic factors at different planting sites, were evaluated. We used variance analysis, correlation analysis, and redundancy analysis (RDA) in this study. The results showed that the yield and chemical component properties of flue-cured tobacco, except for the number of left leaves and plant total sugar (PTS) content, were significantly correlated with climatic factors. Particularly, the yield increased in drier and sunnier weather. In terms of the carbon supply capacity, PTS, petroleum ether (PPE), and starch contents (PS) were higher under high-altitude and high-latitude climatic conditions, whereas for the nitrogen supply capacity, plant nitrogen (PTN) and nicotine (PN) contents improved under low-altitude and low-latitude climatic conditions. PTS, reducing sugar (PRS), potassium (PTK), chlorine (PCL), and PPE contents were negatively related to soil clay content, soil pH, and soil organic matter, whereas PRS and PTK contents were positively correlated with alkali-hydrolyzed nitrogen (AN). According to RDA, the soil clay, AN, available phosphorus (AP), and soil chlorine content (SCL) strongly affected the quality of flue-cured tobacco. The quality of the K326 and Yun87 cultivars was mostly influenced by moisture, whereas the quality of the Hongda cultivar was mostly affected by temperature. In conclusion, compared with soil properties, climatic factors more significantly affect the yield and quality of Honghe flue-cured tobacco leaves.

[Objective] To determine the effect of microbial fertilizer combined with compound fertilizer on the chemical composition content of flue-cured tobacco leaves. [Method] Before planting the flue-cured tobacco, the local conventional fertilizer varieties and microbial fertilizer were applied to tobacco pond annular hole according to the conventional dosage. The experiment has four groups with different treatments, namely T1: without any fertilization; T2: 4 kg of pure nitrogen per mu, applying humic acid organic-inorganic compound fertilizer with 50 g/plant when planting tobacco; T3: reducing the total amount of conventional fertilization by 50%, and applying 80 g/plant of microbial fertilizer; T4: applying only 80 g/plant of microbial fertilizer. The trial adopted a randomized block design, with 3 replicates for each treatment. After the tobacco leaves were harvested and cured at the maturity stage, 5 kg of the lower (X2F), middle (C3F) and upper (B2F) first-cured samples were taken for chemical composition determination and analysis. [Results] The results show that T3 treatment can effectively increase the total sugar, reducing sugar, total nitrogen, nicotine, potassium, and chlorine content in X2F, C3F, and B2F grade tobacco leaves, which ratios are between 20.10% ∼ 21.03% and 18.90% ∼ 19.90%, 2.68% ∼ 3.26%, 2.28% ∼ 3.15%, 2.21% ∼ 2.50%, 0.56% ∼ 0.72%, meeting the production standards of high-quality tobacco. Secondly, T4 treatment can significantly improve the sugar-alkali ratio, nitrogen-alkali ratio, and potassium-chloride ratio of X2F grade tobacco leaves, and it can improve the sugar-nitrogen ratio of C3F and B2F grade tobacco leaves, but the effect is not significant; T3 treatment has a significant effect on B2F grade tobacco. The nitrogen-nitrogen ratio of tobacco leaves has a significant effect on improving the sugar-nine ratio, potassium-chloride ratio and the sugar-nitrogen ratio of X2F ∼ B2F grade tobacco leaves, but the effect has not reached a significant level. [Conclusion] Microbial fertilizer combined with compound fertilizer can improve the content of chemical components in flue-cured tobacco. On the whole, the application effect of T3 treatment is better, that is, the application effect of 80 g/plant microbial fertilizer and 50% reduction of conventional chemical fertilizer is more ideal.

To comprehensively analyze the stability of the chemical quality of tobacco leaf in Honghe State, and to provide a basis for finding ways to narrow the difference between tobacco leaf quality in Honghe State and maintaining the stability of the quality of tobacco leaves in the tobacco producing area. Statistics were used to analyze the annual stability of Honghe tobacco leaves and the stability of the tobacco planting range from 2014 to 2017. The chemical quality of Honghe tobacco leaves was not stable in different years, the total sugar and reduced sugar content showed the trend of decreasing year by year, in addition, the potassium and chlorine content of the tobacco leaves in this tobacco planting area had been at a low level for four consecutive years. In 2014 - 2017, the total sugar, reduced sugar and chlorine content of the tobacco leaves in Honghe State were all relatively small, while the variation coefficient values of nicotine and potassium content in tobacco leaves were large, while the chlorine content in tobacco leaves was extremely unstable between years. For four consecutive years, the chemical quality of tobacco leaves in seven tobacco - planting counties and cities in Honghe State was significant. The chemical quality of tobacco leaves in Honghe State was unstable between different counties and cities.