| Flue-cured tobaccos is one of the most important special economic crops in China,and Panxi Region is the most suitable origin for high quality tobaccos.In this paper,by applying the methods of field trial,laboratory analysis,and expert evaluation,the author studies the appearance qualities,chemical constitutions,sensory qualities,aroma components and others as well as the regional classification by quality of the flue-cured tobaccos in Panxi region of Sichuan Province,China(seventeen cities and towns,including Liangshan Yi Autonomous Prefecture and Panzhihua City),and discusses the correlation between quality characteristics of flue-cured tobacco in Panxi Region and main meteorological elements(such as temperature,sunshine,precipitation and so on).The author also analyses the quality features of flue-cured tobaccos from each origin in Panxi Region and key climatic factors that result in such features,studies the key cultivation techniques and their principles that result in these qualities and features,and integrates the key cultivation techniques that can optimize tobacco qualities,based on the characteristics of Panxi Tobacco-growing Region.The results are as follows:1.The quality features and characteristics of the flue-cured tobaccos from the tobacco-growing regions in Panxi Region of Sichuan Province show that: the leaves of flue-cured tobacco have golden color,pure and vivid lustre,and mildly loss structure;they contain moderate amount of tobacco tar and balanced chemical components.Leaves growing on the lower parts of tobacco plants have “medium” taste qualities,while leaves growing on the lower parts of tobacco plants have “superior” taste qualities.They have distinctively refreshing fragrance which consists of prominent sweetness and slight scorch aroma.Their smoke have relatively high density and moderate tenderness,with strong impact force.In accordance with the quality classification of tobacco leaves in Panxi Region,It can be divided into the classic area,variety Region and sub-variety area.the classic area is within Dechang County,Ningnan County,Butuo County,Meigu County,and Renhe District;its variety Region is within Huidong County,Miyi County,Puge County,Zhaojue County,Xide County,and Yuexi County;and its sub-variety area is within Huili County,Yanbian County,Yanyuan County,Xichang City,Mianning County and Ganluo County.The climates of Panxi Region can be classified into three types: Type 1 Area refers to tobacco-growing Region in Huili County.In cured Tobacco Growing,The average temperature is 20.4?,Its rainfall 824.5mm,Its sunshine time is 1345.3h,Very close to the Zimbabwe Tobacco ecological conditions,With the production of quality tobacco climate characteristics.Type 2 Area consists of eleven tobacco origins,i.e.Zhaojue County,Ningnan County,Xichang County,Yanyuan County,Yanbian County,Renhe District,Butuo County,Huidong County,Dechang County,Miyi County,and Puge County;Compared with the Zimbabwe Tobacco Growing Areas,Its rainfall is less than normal,only745.84 mm.Type 3 Area includes five tobacco origins,i.e.Mianning County,Yuexi County,Ganluo County,Xide County,and Meigu County.Compared with the Zimbabwe Tobacco Growing Areas,Its rainfall is less than normal(726.6mm),Its temperature is low(The average temperature is 19.5?),but it is in the range of climate which Production of high-quality tobacco.Tobacco leaves in Panxi Region have remarkable and relatively consistent characteristics and features.The key meteorological elements that affect the quality of local tobacco are temperature and sunshine.Effect of temperature on the flue-cured tobacco in Panxi tobacco zone growth is not significant,Low temperature significantly affected.Time and area of low temperature on Growth of Tobacco is:Rosette stage period(Zhaojue County,Meigu County,Yanyuan County,Yuexi County,Mianning County,Butuo County),Vigorous growth period(Zhaojue County,Yanyuan County,Butuo County),Mature period(Mianning County,Yuexi County,Xide County,Meigu County,Zhaojue County,Yanyuan County,Butuo County).Compare with high quality tobacco producing areas,In transplanting period to growing period,generally high sunshine hours in Panxi tobacco-growing region,between 10.4%?65.7% and 87.9%?181.9%,Sunshine hours in the appropriate range in the mature period In most tobacco-growing region.Other than key meteorological elements,temperature and sunshine,the main reason that causes the discrepancy between climate suitability and the spread of tobacco leaves of different quality also include variety selection,cultivation techniques and other factors that greatly affect the quality of tobacco leaves.In addition,the traditional rating system of tobacco leaves quality is inclined to the appearance quality,which results in discrepancy and disparity between the exterior and interior quality.2.The adaptability selection of fragrant flue-cured tobacco varieties shows that: There are 8 varieties—K326,NC71,Yunyan105,Yunyan203,Yunyan317,NC102,09011,and Honghua Dajinyuan—that are capable of adapting to the environment of Panxi Region in Sichuan Province;the new varieties of flue-cured tobaccos,such as Yun Tobacco 105,NC102,and 09011,can be planted for demonstration and promoted in Panxi Tobacco-growing Region.3.The study result of different transplanting and harvesting periods' influence on the physiological and biochemical properties of flue-cured tobaccos and the content of aroma constituents is as follows:(1)An early transplanting(14 days in advance)and a delayed harvest(5 days in delay for tobacco leaves at the middle and upper parts of the plants)can promote the growth of tobacco plants,reduce the nicotine content,and help the balance of sugars,potassium,final-stage aroma substances and so forth.(2)According to the analyses on the ecological and agricultural production conditions in Panxi Tobacco-growing Region,the transplanting of flue-cured tobaccos should be finished between April 15 and April 30.Leaves growing on the lower parts of tobacco plants should be harvested at suitable time and those on the middle and upper parts should be harvested 5 days later.(3)In Panxi Tobacco-growing Region,hardy varieties should be planted in high-elevation Region,and drought-resistant varieties in arid Region,supporting by the techniques of transplanting small seedlings under plastic films or drought-resistant cultivation.The ecological advantages of Panxi Tobacco-growing Region can be demonstrated,and the "delicate and sweet fragrances” of those tobacco varieties can be reflected.4.Potassium fertilizer is a critical factor affecting the quality of flue-cured tobacco.The influence of potassium fertilizer management on the photosynthesis,yield,and quality of flue-cured tobaccos is as follows: In Panxi Tobacco-growing Region,with the climate conditions being “drought before humidity”,the ratio of basal dressing top dressing is 3 to 7 so as to supply potassium at the level of to 180 kg·hm-2,which is beneficial for improving the shapes and properties of tobacco leaves,increasing the ability of photosynthesis,promoting the balance of their chemical constitution,increasing the proportion of high-grade and intermediate-grade tobaccos,and improving both between yield and quality of tobacco leaves.It also helps optimize the textures of tobacco leaves,increase the weight of single leaf,and ultimately improve the industrial applicability of those tobacco leaves.The impact of fertilizer proportion method is greater than that potash fertilizer.5.The potassium fertilizer amount and remaining leaves number has a significant impact on the yield and production value of tobacco leaves.The interactive effect of the potassium fertilizer amount and remaining leaves number has increased the yield and production value of tobacco leaves as well as the content of total sugar and reducing sugar to remarkable levels.In Panxi Tobacco-growing Region,the suitable level of nitrogen application is 75kg·hm-2,and the preferable remaining leaves number is from18 to 20.6.This paper summarizes the style characteristics of flue-cured tobacco leaves in Paxi Region,i.e.“refreshing,sweet,and fragrant”,and improves the key cultivation techniques system of flue-cured tobacco leaves in Panxi Region,with variety selection as its base,management of potassium and nitrogen as its core,as well as the method of early planting and late harvest as its key point,in order to enhance the quality of tobacco produced in Panxi Region. |
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