| The research was based on Wumeng tobacco-growing areas in Guizhou,and took Yunyan 97 as materials.In order to analyze the relationship between the altitude and the quality indicator of Yunyan 97,the difference of the ultrastructure of Yunyan 97 leaf cells at different altitudes were observed,and the difference of key enzyme activity of carbon and nitrogen metabolism,the quality of appearance,the physical property,the chemical composition,the aroma substances and the sensory quality of Yunyan 97 at different altitudes were compared and analyzed.The main conclusions were showed as follows:1.Wumeng tobacco-growing areas had the typical Karst landform characteristics,the tobacco planted environment was complex,and the altitude was span,and the characteristic of climate was solid vertical distribution.Due to the above reasons,the tobacco-growing areas were divided into 3 altitudes: low altitude(<1700m),middle altitude(1700 ~ 2100m)and high altitude(>2100m).The flooded dam of Restoration town in Nayong County(1600.6 m)was selected as the low altitude sampling points and Xiangshui village of Blacksmith town in Hezhang County(1943.9 m)was selected as the middle altitude sampling points,and Chahe village of Chahe town in Weining County was selected as the high altitude sampling points.The main climate indexes of the growth duration after transplanted in Wumeng tobacco-growing areas were tested,and the results showed as follows: the sunshine duration was 580.30~960.10 h,and the average temperature was 12~13℃,the precipitation was 666.70~970.90 mm and the frost-free period was 245~266d in Wumeng tobacco-growing areas during the field growth phase(Early April ~ Late September),and daily temperature and the cumulative temperature of equal to or greater than 10 was 3908.9℃ ℃,and while the precipitation in root elongation stage was less and the drought happened a lot;and the temperature of the growth duration was suitable after transplanted,and cumulative temperature was equal to or greater than 10 was 3778.2℃ ℃,and the indexes of precipitation and sunshine duration were quite stable and it was very suitable for the growth of high quality flue-cured tobacco in middle altitudes;and the thermal conditions were less and the temperature was low in high altitudes during the field growth period,and the cumulative temperature of equal to or greater than 10 was 3597.3℃ ℃.The adequate sunshine,suitable temperature,plenty rainfall during the later period of flue-cured field stages,large temperature difference between day and night and more night rain in rainy season were the advantages of the growth of high quality flue-cured tobacco in Wumeng tobacco-growing areas;but the insufficient rainfall during tobacco transplanting period and the earlier period of flue-cured field stages,and too much rainfall happened during the later period of flue-cured field stages,and the fluctuant temperature and low temperature occurred during the mature period were the disadvantage factors.2.The physical properties and appearance qualities of the middle leaf of flue-cured tobacco were analyzed in different altitudes.The performance of single leaf weight,leaf width,leaf length,stem ratio and tension stress in different altitudes was high altitudes> medium altitudes> low altitudes;and the performance of leaf density in different altitudes was low altitudes> medium altitudes> high altitudes,and the difference was significant between low altitudes and middle and high altitudes;and the performance of padding values was medium altitudes> low altitudes> high altitudes and the difference was significant among three altitudes.The results of appearance qualities showed as follows,the color score and identity in different altitudes were low altitudes> high altitudes> middle altitudes;and the leaf structure and the color score was medium altitudes> high altitudes> low altitudes;and the maturity and the oil score and the total score was medium altitudes > low altitudes > high altitudes,and there was no significant difference among the altitudes.3.The chemical composition of the middle leaf of flue-cured tobacco was analyzed in different altitudes.The results showed the nicotine content was highest in low altitudes,and then followed by high altitudes and the content of nicotine was lower in middle altitudes,and the difference was insignificant in three altitudes.The total sugar content was highest in high altitudes,and the difference was insignificant in high altitudes,and significantly higher than the low altitudes.The reducing sugar content and the ratio of sugar and nicotine were highest in middle altitudes and significantly higher than other altitudes.The total nitrogen content and the ratio of nitrogen and nicotine were highest in middle altitudes and the difference between the high altitude and the low altitude was insignificant.4.The smoking quality of flue-cured tobacco middle leaf was tested in different altitudes in Wumeng tobacco-growing areas,and it revealed that the aroma quality,the aroma quantity,the aftertaste score and the smoking total scores of the flue-cured tobacco were higher in middle altitude than the low altitude and high altitude,and the flue-cured tobacco sweetness was highest in middle altitude,and the fresh and sweet incense of flue-cured tobacco was most prominent in middle altitudes,and the flue-cured tobacco had the characteristics of high quality aroma,less irritation,clean finish,soft gas,sweet tasty,moderate concentration,medium momentum with the distinctive ecological condition in Wumeng tobacco-growing areas,and the flue-cured tobacco had a typical characteristic of fresh and sweet incense,especially in middle altitudes.5.The results showed that the appearance of aromatic amino acid metabolism content appeared in the trend of first increased then decreased along with the changes of altitudes,and the content of benzaldehyde and phenylacetaldehyde in tobacco in the middle altitude was highest;the content of browning products decreased with the rise of altitude,and low altitude> medium altitude> high altitude;the performance the total content of solanone of cembratriendiol group showed was high altitude> low altitude> medium altitude;the content of carotenoid in low altitude was highest,and there was little difference between high altitude and medium altitude;and the relationship between the neophytadiene content and altitude was close,and the appearance was that the content of neophytadiene decreased with the rise of altitude.In a word,the content of neutral aroma component(except neophytadiene)was highest compared with other areas in low altitudes,and the content was 190.80μg/g,and the content of neutral aroma component was lowest,and the content was 167.14μg/g.6.The ultrastructure of Yunyan 97 leaf cells during its growth and development was observed,and according to research the structure of chloroplast and cell wall and the distribution of starch grain,and the cellular organs were abundant in cytoplasm and cell nucleus wrer normal in all of the sample cells,and jthe cellular morphology and physiological functions were better.The main difference of chloroplast in the tobacco leaf cells between different altitudes was the accumulation of starch grains,and the volume and number of the starch grains in flue-cured tobacco were significantly changed in the middle altitude areas after transplanted 60 d,and the increase of the volume and numbers of starch was superior to the high and low altitude areas,and this might be one of the main reasons for high sugar content in middle altitude in Wumeng tobacco areas,and it was also more reasonable to extent the high quality tobacco production in middle altitudes.7.By comparing the enzyme activity of carbon and nitrogen metabolism of flue-cured tobacco during different growth periods at three altitudes,the study found that after transplanted 30 d to 50 d,the activity of invertase in middle altitude areas was higher than the high attitude areas,and the activities of sucrose synthase and amylase was lower than the high altitude areas.These factors contributed to an exuberant carbon metabolism and a higher accumulation of sucrose.After transplanted around 70 d,the activity of sucrose phosphate synthase in middle altitude areas was highest,and the accumulation of starch content was higher in this stage.And the moderate activity of sucrose synthase contributed to sucrose inversion and starch synthesiswas,and the sugar content in middle attitude areas was the highest finally.In the nitrogen metabolism,the change of nitrate reductase and glutamine synthetase activities was relatively simple,and both were reduced after the first rise,and nitrogen metabolism in the early,and then carbon metabolism.The activity of glutamine synthetase in middle altitude areas was highest,and promoted the maturation of tobacco and made the content of nitrogen and nicotine in middle attitude areas more lower than the high and low altitude areas.During the growth of flue-cured tobacco,the coordination of enzyme activity made the ratio of sugar and nicotine and the ratio of nitrogen and nicotine in middle altitude areas superior than the high and low altitude areas.Overall,the altitude was an important factor influenced the carbon and nitrogen metabolism of flue-cured tobacco in Wumeng.Compared with the high and low altitude areas,the development of the tobacco cell at middle altitude areas in Wumeng was more reasonable,the coordination of carbon and nitrogen metabolism was better and the chemical composition was more coordinated could be used as a predominant area for the specialties tobacco in Wumeng.This paper analyzed the main reasons of high sugar content and the characteristics of fresh and sweet incense in tobacco leaves in middle altitude in Wumeng tobacco areas,and in addition to the altitude,the effects of other ecological factors on carbon and nitrogen metabolism of the flue-cured tobacco needed a further study. |
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