| On the basis of Enshi tobacco-growing areas of Hubei Province, the flue-cured tobacco quality and climate conditions were analyzed. And by applying membership function and estimating weight values for each index by using the method of principal component analysis, climate feasibility and tobacco quality usability were comprehensively evaluated. Climate feasibility indexs (CFI) and chemical components usability indexs (CCUI) of flue-cured tobacco were proposed and estimated. Chemical components in flue-cured tobacco leaves were analyzed at different altitudes of Enshi tobacco-growing areas, the influences of climate 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 indexs for eight counties(cities) of Enshi tobacco-growing areas in Hubei Province, climate status and climate feasibility indexs were analyzed, and similarity analysis of climate conditions between Enshi tobacco-growing areas and high-quality tobacco-growing areas overseas was also conducted. Enshi tobacco-growing areas had a long frost-free period, feasible temperature, high accumulated temperature of≥10℃, abundant precipitation, and low sunlight. Each climate index showed a big variation among Enshi tobacco-growing areas, coefficient of variation(6.36%) of average temperature was smallest during growing stage, coefficient of variation(13.35%) of precipitation was largest during growing stage, average temperature of Enshi tobacco-growing areas was higher than overseas, and precipitation of Enshi tobacco-growing areas was much than overseas. The climate feasibility indexs(CFI) for Enshi tobacco-growing areas was 0.792±0.039, CFI (0.848) of Lichuan was largest, CFI(0.729) of Hefeng was smallest. Based on climate factors, tobacco-growing areas could be classified into three groups by cluster analysis, each group had different climate characteristics. The first group included Lichuan and Xianfeng, CFI was medium. This group had medium precipitation, lower temperature, lower accumulated temperature of≥10℃and sunlight during field period, so climate condition was suitable for high-quality tobacco development. The second group included Jianshi, Enshi, Xuan'en, Hefeng and Laifeng, CFI was lower. This group had medium temperature, accumulated temperature of ≥10℃and ample sunlight, but high precipitation during field period, climate condition was worse than other groups. The third group included Badong, CFI was high. This group had high temperature, accumulated temperature of≥10℃and ample sunlight, but lower precipitation during field period, it could meet the needs of water for tobacco development, this climate condition was more suitable for high-quality tobacco development. Similarity analysis of climate conditions between Enshi tobacco-growing areas and high-quality tobacco-growing areas overseas was conducted, the climate similar distance was 0.415 between Enshi tobacco-growing areas and America, 0.397 between Enshi tobacco-growing areas and Brazil, and 0.371 between Enshi tobacco-growing areas and Zimbabwe, the climate similar distance was smallest between Badong and overseas, the climate similar distance was biggest between Hefeng and overseas.2. Climate condition of Enshi tobacco-growing areas could be classified into three groups at different altitudes areas, including lower altitude(<800m), medium altitude(800～1200m), high altitude(>1200m). Based on climate data of eight indexs at different altitudes of Enshi tobacco-growing areas, climate status and climate feasibility indexs at different altitudes were evaluated, similarity analysis of climate conditions between Enshi tobacco-growing areas and high-quality tobacco-growing areas overseas was analyzed.Frost-free period turned to shorter, average temperature and accumulated temperature of≥10℃turned to lower, sunlight and precipitation turn to more abundant along with increasing of altitudes. Average temperature, precipitation, sunlight, accumulated temperature of≥10℃and frost-free period during field period had significant difference among different altitudes. It showed that the significant trend of low altitude > medium altitude > high altitude except frost-free period between medium altitude and high altitude. CFI values at different altitudes showed that low altitude(0.903) > medium altitude(0.734) > high altitude(0.660), CFI had significant difference among different altitudes. The similarity of the climate conditions at different altitudes of Enshi tobacco-growing areas with overseas showed that low altitude > medium altitude > high altitude.3. Based on flue-cured tobacco samples from Enshi main tobacco-growing areas, main chemical components, mineral components and neutral aroma components of flue-cured tobacco leaves were analyzed, and chemical components usability indexs (CCUI) of flue-cured tobacco leaves were evaluated. The contents of total sugar, reducing sugar, Total N, nicotine and K were medium, the content of Cl was lower, K/Cl was high, and main chemical components reached the level of high-quality tobacco overseas. Total sugar, reducing sugar, nicotine, K, TS/Nic and K/Cl had significant difference among different grades, and main chemical components had significant difference among different cultivars. Average chemical components usability indexs (CCUI) for Enshi flue-cured tobacco leaves was 0.724±0.076, coefficient of variation was 10.44%. CCUI of different tobacco-growing areas showed that the trend of Hefeng>Enshi>Jianshi>Badong>Xuan'en>Lichuan>Xianfeng, CCUI of different grades showed that the trend of C3F>B2F>X2F. Mineral components showed a big variation in flue-cured tobacco, coefficient of variation(99.88%) of Cu was biggest, coefficient of variation(17.65%) of P was smallest, contents of P, Mg, B, Fe, Mn and Zn had significant difference with Brazil. Contents of Ca, B and Fe had significant difference among different grades, and contents of P, Mg, B, Cu and Zn had significant difference among different cultivars. Total neutral aroma components showed that the trend of X2F(741.02μg/g)>C3F(728.76μg/g)>B2F(693.66μg/g).4. Based on fifty-eight flue-cured tobacco samples from different altitudes of Enshi tobacco-growing areas, main chemical components, mineral components and neutral aroma components of flue-cured tobacco leaves were analyzed at different altitudes areas. Contents of starch, K and K/Cl had significant difference at different altitudes, other chemical components had not significant, contents of total sugar, reducing sugar and nicotine showed that the trend of medium altitude>low altitude>high altitude, contents of starch showed that the trend of medium altitude>high altitude>low altitude, contents of K and K/Cl showed that the trend of high altitude>medium altitude>low altitude, contents of TS/Nic showed that the trend of low altitude>medium altitude>high altitude. Content of P had significant difference at different altitudes, other mineral components had not significant difference at different altitudes. Total neutral aroma components showed that the trend of medium altitude(782.19μg/g)>high altitude(715.15μg/g) >low altitude(690.18μg/g).5. 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, increasing average temperature during field period could be helpful for increasing contents of total sugar and reducing sugar, increasing precipitation during field period could be helpful for decreasing contents of total sugar and reducing sugar. Sunlight during field period had significant positive correlation with K and K/Cl, and negative correlation with total sugar and Cl. Accumulated temperature of≥10℃had significant positive correlation with total sugar and Cl, and negative correlation with K and K/Cl. Each climate index had not significant correlation with starch, nicotine and TS/Nic in flue-cured tobacco leaves. Increasing average temperature and accumulated temperature of≥10℃, properly decreasing precipitation could be helpful for improving quality of flue-cured tobacco leaves. By applying stepwise regression analysis, the effects of climate 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 had different influence on chemical components in tobacco leaves. |
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