| On the basis of the surrounding areas of Shennongjia in Hubei Province, the flue-cured tobacco quality and ecological conditions including climate and soil factors were analyzed. And by applying membership function and estimating weight values for each index by using the method of principal component analysis, tobacco quality usability, climate feasibility and soil fertility were comprehensively evaluated. Climate feasibility indexes (CFI), integrated fertility indexes (IFI) and chemical components usability indexes (CCUI) of flue-cured tobacco were proposed and estimated. Chemical components in flue-cured tobacco leaves were analyzed at different altitudes of the surrounding areas of Shennongjia, the influences of climate factors and soil factors on contents of chemical components in flue-cured tobacco leaves were also studied. Main results were as follows:1. Based on climate data of eight indexes for six counties of the surrounding areas of Shennongjia, principal component analysis was conducted to determine the weight value of climate indicators such as the mean temperature during root extenting stage, vigorous growing stage and mature stage, the rainfall during root extenting stage, vigorous growing stage and mature stage, the accumulated temperature of≥10℃and the daylight hours of field period. The climate feasibility indexes (CFI) were quantitative estimated, climate status and climate feasibility indexes were analyzed. The results indicated that: (1) The surrounding areas of Shennongjia had a long frost-free period, feasible temperature, abundant precipitation, a long sunlight, and high accumulated temperature of≥10℃. Each climate index showed a big variation among the surrounding areas of Shennongjia, coefficient of variation(5.63%) of average temperature was smallest during growing stage, coefficient of variation(19.07%) of the annual rainfall was largest, average rainfall of the surrounding areas of Shennongjia was higher than overseas. (2) The climate feasibility indexes (CFI) for Shennongjia surrounding areas was 0.781±0.051, CFI (0.835±0.032) of Zhushan was largest, CFI (0.703±0.032) of Badong was smallest. CFI of different tobacco-growing areas showed that the trend of Zhushan>Nanzhang>Baokang>Fangxian>Xingshan>Badong.2. Climate condition of the surrounding areas of Shennongjia could be classified into three groups at different altitudes areas, including lower altitude(<800 m), medium altitude(800～1200 m), high altitude(≥1200 m). Based on climate data of eight indexes at different altitudes of the areas, principal component analysis was conducted to determine the weight value of climate indicators such as the average temperature during root extenting stage, vigorous growing stage and mature stage, the rainfall during root extenting stage, vigorous growing stage and mature stage, the accumulated temperature of≥10℃and the daylight hours of field period. The climate feasibility indexes (CFI) were quantitative estimated, climate status and climate feasibility indexes at different altitudes were evaluated, and similarity analysis of climate conditions between Shennongjia surrounding areas and high-quality tobacco-growing areas overseas was analyzed. The results indicated that: (1) Frost-free period turned to shorter, the days for daily average temperature of≥20℃and average temperature and accumulated temperature of≥10℃turned to lower, sunlight and precipitation turn to more abundant along with increasing of altitudes. (2) The mean of the climate feasibility indexes (CFI) for low altitude was 0.704, the mean of CFI for medium altitude was 0.671, and the mean of CFI for high altitude was 0.621, the climate feasibility indexes (CFI) showed that the trend of decreased with the altitude increased. (3) The similarity of the climate conditions at different altitudes between Shennongjia surrounding areas and tobacco-growing areas abroad showed the trend of Brazil (0.995 for low altitude, 0.997 for medium altitude and 0.997 for high altitude) > Zimbabwe (0.993 for low altitude, 0.995 for medium altitude and 0.995 for high altitude) > America (0.989 for low altitude, 0.992 for medium altitude and 0.992 for high altitude). The similarity analysis could be used as a reference to make full use of the climate resources in the surrounding areas of Shennongjia.3. Based on 63 soil samples in 6 countries from the surrounding areas of Shennongjia,the soil nutrients contents and fertility status were analyzed systemically. The results indicated that the content of soil pH (5.58±0.93) was suitable; the content of soil organic matter was middle or slightly low, with the mean of (23.66±7.80) g/kg; the contents of soil total N and hydrolysis N were suitable, with the mean of (1.53±0.45) g/kg and (111.45±30.40) mg/kg;the contents of soil total P were low, with the mean of (0.93±0.71) mg/kg, and the available P with the average content of (9.54±5.44) mg/kg, in a very phosphorus deficiency state; the contents of soil total K, available Fe, available Cu, and available S were rich, with the mean of (19.13±3.94) g/kg, (13.26±3.69) mg/kg, (1.48±0.54) mg/kg and (30.13±14.39) mg/kg;the contents of soil available K, available Zn and available Mn were low, with the mean of (112.76±43.27) mg/kg, (0.60±0.41) mg/kg and (5.42±4.21) mg/kg ; the contents of soil available Mo, exchangeable Ca and exchangeable Mg were extremely rich, with the mean of (0.47±0.32) mg/kg, (18.88±6.31) cmol/kg and (5.08±2.05) cmol/kg; the content of soil water-soluble Cl was very low, with the mean of only (4.13±1.09) mg/kg.4. The situation of the main nutrient at different altitude tobacco soil samples of the Shennongjia surrounding areas were analyzed and evaluated, and the results showed that: (1) The condition of soil fertility was suitable for high quality tobacco-growing in general, the contents of the soil organic matter, total N, total K and hydrolysis N were increased along with increasing of altitudes. the content of P and water-soluble Cl were widely deficient at different altitudes. (2) Except the coefficient of variation of pH and total K were smaller at different altitudes, the coefficient of variation of other nutrient content were bigger; the contents of organic matter and hydrolysis N reached to 5% significant level between higher altitude and lower altitude, and other nutrient content were not at at different altitudes. (3) The integrated fertility index of soil fertility at different altitudes was: higher altitude > medium altitude > lower altitude, which reached to significant level between higher altitude and medium altitude.5. Studied on growth regularity of flue-cured tobacco at different altitude of the Shennongjia surrounding areas, the results showed that: (1) The growth rate at different altitudes showed the trend of lower altitude > medium altitude > higher altitude, with the mean of (0.96±0.11) g DW per plant and per day, (0.79±0.14) g DW per plant and per day, and (0.50±0.29) g DW per plant and per day. (2) The biomass at different altitudes showed the trend of lower altitude > medium altitude > higher altitude, the biomass changed in the sequence: leaves > stems > roots at harvest; the biomass of roots, stems and leaves changed in the sequence: lower altitude > medium altitude > higher altitude at different altitudes.6. Based on flue-cured tobacco samples from the Shennongjia surrounding areas, main chemical components and neutral aroma components of flue-cured tobacco leaves were analyzed, and chemical components usability indexes (CCUI) of flue-cured tobacco leaves were evaluated, the results showed that: (1) The contents of total sugar, reducing sugar and total N and the K/Cl were medium, the content of nicotine was high, the content of K and Cl were slightly lower, the sugar-nicotine ratio and nitrogen-nicotine ratio were relatively low. Total N, nicotine, K, RS/Nic, N/Nic and K/Cl had significant difference among different grades, total sugar, reducing sugar and RS/Nic had significant difference among different cultivars; and total sugar, reducing sugar total N, Cl, N/Nic and K/Cl had significant difference among different years. (2) The average chemical components usability indexes (CCUI) of flue-cured tobacco leaves for Shennongjia surrounding areas was 0.720±0.091; CCUI of different tobacco-growing areas showed that the trend of Baokang>Nanzhang>Badong> Xingshan>Fangxian>Zhushan; CCUI of different grades showed that the trend of C2F>C3F>B2F>X2F. (3) Total neutral aroma components showed that the trend of C2L>C3L>C3F>X3F.7. Based on flue-cured tobacco samples from different altitudes of Shennongjia surrounding areas, the main chemical components were analyzed and evaluated at different altitudes. The results showed that: (1) The content of total sugar, reducing sugar, K and the RS/Nic, N/Nic had significant difference among different altitudes, and the others had no significant difference. (2) The chemical components usability indexes (CCUI) of flue-cured tobacco leaves of different altitudes showed that the trend of medium altitude>low altitude>high altitude, with the means of 0.761±0.09, 0.731±0.08 and 0.702±0.06, and the CCUI of different altitudes had no significant difference.8. The correlation analysis of eight climate indexs with chemical components in flue-cured tobacco leaves was researched. The results indicated that average temperature during field period had significant positive correlation with total sugar and reducing sugar, and precipitation during field period had significant negative correlation with total sugar and reducing sugar, precipitation during field period had significant positive correlation with total N, K and K/Cl, average temperature during field period had significant negative correlation with K and K/Cl. Sunlight during field period had significant negative correlation with K and K/Cl, and negative correlation with K. Accumulated temperature of≥10℃had significant positive correlation with total sugar, reducing sugar and K, and egative correlation with K/Cl. Each climate index had not significant correlation with nicotine, RS/Nic and N/Nic. By applying stepwise regression analysis, the effects of climate factors and soil nutritions factors on chemical components in flue-cured tobacco leaves were studied and the best regression equations were established. The results indicated that different climate factors and soil nutritions factors had different influence on chemical components in tobacco leaves.
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