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Flue-cured tobacco in Yunnan province had elegant flavor, velvety and smooth smoke, which was representative fen-flavor. In the base of Qujing tobacco-growing areas in Yunnan Province, not only each index of the 973 flue-cured tobacco samples from specified soil samples located in nine Qujing prefectures were tested, but also the attributes of quality and soil factors on style of fen-flavor flue-cured tobacco in Qujing district were analyzed. Main results were as follows:1. Style of fen-flavor flue-cured tobacco was analyzed in Qujing district of Yunnan province. Overall, aroma type scored 4.03±0.67, with range from 0.00 to 5.00, with verged on normal distributions. It displayed negative bias cliff peaks distributions and concentrated data. The average score of flue-cured tobacco samples with prominent fen-flavor characteristics was 4.28, with the proportion of 66.60%. While the average score of flue-cured tobacco samples with middle and weak fen-flavor characteristics were 3.21 and 1.81, with the percentage of 32.06% and 1.34% respectively. The whole samples from Qilin district had prominent fen-flavor characteristics, which scored 4.50±0.53 and reached to maximum. It had no remarkable difference with Fuyuan country, but was significantly higher than other countries.2. Distribution of pH and soil nutrients in 973 soil samples from Qujing tobacco-growing regions was analyzed. The distribution of soil pH and soil nutrients contents were close to normal. The organic matter, total nitrogen, total phosphorus, total potassium, alkaline hydrolytic nitrogen, available phosphorus and potassium demonstrated positive bias cliff peaks distribution, but the pH assumed negative bias flat peaks. The soil samples with optimum pH range （5.57.0） for the flue-cured tobacco growth seized 55.91%, and the proportion of the organic matter in the zone of 20.0g/kg to 40.0g/kg was 54.06%. 67.94% of the total nitrogen in 973 soil samples ranged from 1.0 g/kg to 2.0 g/kg, and the total phosphorus ranged from 0.8g/kg to 2.0g/kg in all soil samples took up 69.68%. The proportion of the total potassium ranged from 10.0 g/kg to 22.0g/kg was 53.96%, and alkaline hydrolytic nitrogen distributed from 60.0mg/kg to180.0mg/kg with the percentage of 86.02%, while the available phosphorus was between 10.0 mg/kg and 30.0mg/kg with the ratio of 53.55%. The available potassium ranging from 100.0mg/kg to 200.0mg/kg held 44.60% in 973 soil samples.Distribution of pH and soil nutrients of different tobacco-growing agrotype was analyzed. The results indicated that: 1) Soil pH was in the feasible scale for growth of flue-cured tobacco, particularly the red soil was relatively high. 2) The content of organic matter and alkaline hydrolytic nitrogen was supreme in yellow soil, reaching to 41.91 g/kg and 153.02 mg/kg respectively, and was significantly higher than other soil types. 3) The concentration of available phosphorus in red soil, yellow soil and paddy soil was comparatively high. 4) The available potassium in red soil with the content of 275.07 mg/kg was highest, which was remarkably higher than other soil types.3. Effect of the soil factors on style of fen-flavor flue-cured tobacco was analyzed. There existed significant difference of characteristic of fen-flavor flue-cured tobacco in different soil types. The characteristic of fen-flavor flue-cured tobacco in red soil was most evident, which the contents of available phosphorus and potassium were relatively high, with the proportion up to 76.33% of the total samples. Tobacco-growing soils associated with prominent fen-flavor characteristics of flue-cured tobacco had suitable pH （6.05）, comparatively low contents of organic matter, total nitrogen and alkaline hydrolytic nitrogen, showing the highest contents of total phosphorus, total potassium, available potassium and available iron, and were notably higher than those of flue-cured tobacco with weak fen-flavor characteristic.The grey relational analysis was applied to analyze the relationship between style of fen-flavor flue-cured tobacco and soil factors. For aroma types, the highest relational degree was with total phosphorus content in soil, followed by total nitrogen content. Also, soil factors including available iron, available magnesium, available potassium and alkaline hydrolytic nitrogen had large effects on styles of fen-flavor. Its stepwise regression equation was（?） = 2.89-11.06x3 +18.41x4-0.01x6+0.005x8-0.004x10+0.01x13-1.40x15-0.01x17 through the analysis. On the basis, pathway analysis showed total phosphorus content playing largest net effect on style of fen-flavor flue-cured tobacco, also available magnesium brought about the direct action. The total nitrogen, alkaline hydrolytic nitrogen, rapidly available potassium and available molybdenum not only had strong direct impact on style of fen-flavor flue-cured tobacco, and that could assist other traits through indirect effect.4. Relationship between the style of fen-flavor flue-cured tobacco and chemical composition was analyzed. Prominent fen-flavor characteristic of flue-cured tobacco had highest contents of total sugar, reducing sugar, potassium, phosphorus, volatile acid, petroleum ether extract, rutin,the ratio of reducing sugar to nicotine and potassium to chlorine, existing significantly higher differences between those of flue-cured tobacco with weak fen-flavor characteristic. Weak fen-flavor characteristic of flue-cured tobacco had no significant difference between other fen-flavor types, showing the higher contents of total nitrogen, nicotine, magnesium and volatile acid.The grey relational analysis was applied to analyze the relationship between style of fen-flavor flue-cured tobacco and chemical composition. For aroma types, the highest relational degree was with total sugar content in tobacco, followed by total nitrogen content. Also, chemical compositions including rutin,the ratio of reducing sugar to nicotine, nicotine and petroleum ether extract had large effects on styles of fen-flavor. Stepwise regression equation of the relation was （?）=-2.11+0.07x1+0.39x2-10.64x3-2.79x4+18.96x5+0.71x8+0.02x9-0.83x12+0.004x13+3.05x21-3.01x22+0.11x23+0.05x26.On the basis, pathway analysis showed total sugar content playing largest net effect on style of fen-flavor flue-cured tobacco, and it produced indirect effect. Reducing sugar, total nitrogen, nicotine, volatile acid, petroleum ether extract and rutin affected styles of fen-flavor directly. Nicotine, magnesium, phosphorus, the ratio of reducing sugar to nicotine and potassium to chlorine not only had strong direct impact on style of fen-flavor flue-cured tobacco, and that could assist other traits through more indirect action.5. Relationship between the style of fen-flavor flue-cured tobacco and smoking quality was analyzed. Flue-cured tobacco with prominent fen-flavor characteristic showed better aroma quality, some rich aroma volume, less offensive odor, some moderate remaining flavor, faint irritation, comparatively smaller taste concentration and physiological strength. Its agglomerating ability, sweetness and softness were significantly higher than flue-cured tobacco with middle or weak fen-flavor characteristic.The grey relational analysis was applied to analyze the relationship between style of fen-flavor flue-cured tobacco and smoking quality. For aroma types, the highest relational degree was with aroma volume, followed by smoking total scores. Also, smoking quality including aroma quality,remaining flavor, combustibility and softness had large effects on styles of fen-flavor. Stepwise regression equation of the relation was （?） = -15.54+0.32x1 +0.29x2-0.35x4+0.15x5+1.10x6-0.68x7+0.52x13+0.22x14.On the basis, pathway analysis showed aroma volume playing largest net effect on style of fen-flavor flue-cured tobacco. Aroma volume, aroma quality,remaining flavor, combustibility, ash color and softness mainly produced indirect effect. Total smoking scores affected styles of fen-flavor directly. Irritation both had strong direct impact on style of fen-flavor flue-cured tobacco and assisted other traits through more indirect action.
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