Studies on Amylase and Degradation of Starch and Pigment of Tobacco Leaf During Process of Flue-Curing

The changes in the activity of amylase and amylase-isoenzyme and the degradation of starch and pigment of tobacco leaf during flue-curing were studied by using the electric- heated flue-curing barn designed and made by the Henan Agricultural University. The temperature and humidity of the barn were controlled automatically. The results indicated that starch in tobacco leaf decreased rapidly and leveled off after 48 h of curring, in the meantime, the content of soluble sugar increased accordingly and reached a peak at the stage of color-fixing. Both of them had a rapid-changing stage in the first 36 hours of yellowing. The changes of starch and soluble sugar contents had highly significant negative-correlation at 1 % level (rNC89 = -0.8962**, rYY85 = -0.9704**). The activity of amylase increased with the proceeding of curing and reached a peak after 36 hours of curing, then decreased. But the activity of amylase kept at a high level when the humidity of curing-environment was very low, even if the tobacco leaf had been dried. The rapid degradation of starch showed a significantly negative correlation with the increase of activity of amylase at 5 % level (rNC89 = -0.8495*, rYY85 = -0.7839*). The degradation of starch and pigment had the same regulation and had highly significant correlation at 1 % level (rNC89= 0.9649**, rYY85= 0.9428**). There were mainly three amylase-isoenzyme bands -A, B, C respectively, in tobacco leaf during flue curing. They were identified as α-AMY, β-AMY, R-AMY, and the activity of β-AMY was the highest. The changes in amylase activity and contents of starch and pigment were affected by the tobacco leaf moisture and environmental humidity during curing.

Changes of Polyphenols in Tobacco Leaves During the Flue-Curing Process and Correlation Analysis on Some Chemical Components

The changes of polyphenols in tobacco leaves during the flue-curing process and correlation analysis on some chemical components were studied. Leaf samples were taken from different tobacco-producing regions in Henan Province, China. The results indicated that the content of total phenols increased during the first 24 h of curing, and then decreased. It reached the lowest value at 72 h of curing and increased rapidly after that. The content of chlorogenic acid also increased during 0-24 h of curing. But the lowest point occurred at 60 or 72 h of curing and then it increased till the end of the curing process. The content of mtin generally increased with curing, and showed little fluctuations. The changes of PPO and POD activity were the opposite. Rutin was found to have a highly significant positive correlation with total sugar （r=0.822^＊＊）, but a highly significant negative correlation with starch, nicotine, and protein.

Effects of Different Flue-curing Technologies on Microscopic Structure of Flue-cured Tobacco Leaves

[Objective] This study aimed to compare the effects of Chinese quality-improving fragrunce-increasing tobacco flue-curing technology, Chinese three- stage tobaeeo flue-curing technology and Zimbabwean tobaceo flue-euring technology on microscopie structure of flue-cured tobacco leaves to provide theoretical basis for tobacco flue-curing. [ Method ] Middle leaves of tobacco cultivar K326 were collected in Pengshui County of Chongqing City for flue-curing experiment using three flue-curing technologies. Leaf samples were collected regularly in the flue-curing process, to investigate the microscopic structure of flue-cured tobaceo leaves. [ Result] During three flue-curing processes, leaves, palisade tissues and sponge tissues shrank gradually. Three flue-euring processes exhibited significant differ- ences in the peak of tissue shrinkage ： microscopic structure of flue-cured tobacco leaves in Chinese three-stage tobacco flue-curing process shrank earliest, follower by Chinese quality-improving fragrance-increasing tobacco flue-curing process; flue-eured tobacco leaves in Zimbabwean tobacco flue-curing process presented the latest shrinkage. At 84 h post-curing, leaf thickness in three flue-curing processes showed a descend order of Chinese three-stage tobacco flue-curing process 〉 Chinese quality-improving fragrance-increasing tobacco flue-curing process 〉 Zimbabwean tobacco flue-curing process. Upper and lower epidermal cells in Zimb- abwean tobacco flue-curing process ruptured earlier than other two flue-curing processes; eventually, the majority of cells ruptured and mixed with palisade tissues and sponge tissues. In Chinese quality-improving fragranee-increasing tobacco flue-curing process, only a small number of epidermal cells in dried leaves ruptured. Among three flue-curing technologies, Zimbabwean tobacco flue-curing technology exhibited the greatest damage to epidermal cells, followed by Chinese three-stage tobaceo flue-curing technology; Chinese quality-improving fragrance-increasing tobacco flue-curing technology had the minimum damage to epidermal cells. Mese- phyll cross-section exhibited significant morphological changes in stomata. To be specific, at 0 - 12 h post-curing, stomata of tobacco leaves closed with slightly prominent stamatal apparatuses on upper and lower epidermis; at 24 -72 h post-curing, stomata of tobaceo leaves changed gradually from opening to closure with significantly prominent stomatal apparatuses on upper and lower epidermis; at 84 h post-curing, stomata of tobacco leaves closed, and the majority of stomatal appa- ratuses were significantly prominent. In Chinese quality-improving fragrance-increasing tobacco flue-curing process, only a small number of epidermal ceils ruptured at 84 h pest-flue-curing; palisade tissues and sponge tissues shrank almost simultaneously. Significant gaps were observed between palisade tissues and between pal- isade tissues and sponge tissues. Chinese quality-improving fragrance-increasing tobacco flue-curing technology exhibited lower disorder level compared with other two flue-curing technologies. [ Conclusion] Chinese quality-improving fragrance-increasing tobacco flue-curlng technology was conducive to maintaining the micro- scopic structure integrity of flue-cured tobacco leaves and obtaining high-quality flue-cured tobacco leaves.

Effects of Different Flue-curing Technologies on Submicroscopic Structure of Flue-cured Tobacco Leaves

[ Objective] This study aimed to compare the effects of low-temperature low-humidity tobacco flue-curing technology, moderate-temperature moderate- humidity tobacco flue-curing technology and moderate-temperature high-humidity tobacco flue-curing technology on submicroscopic structure of flue-cured tobacco leaves to provide theoretical basis for tobacco flue-curing. [ Method] Middle leaves of tobacco cuhivar K326 were collected in Pengshui County of Chongqing City for flue-curing experiment using three flue-curing technologies. Leaf samples were collected regularly in the flue-curing process, to investigate the submicroscopic structure of flue-cured tobacco leaves. [ Result] Morphology changes and structural rupture of chloroplasts occurred at different time during three flue-curing proces- ses. In low-temperature low-humidity flue-curing process, morphology changes and structural rupture of chloroplasts occurred late but rapidly; in moderate-tempera- ture moderate-humidity flue-curing process and moderate-temperature high-humidity flue-curing process, morphology changes and structural rupture of chloroplasts occurred early but slowly. Among these three flue-curing processes, the speed of changes in mitochondria morphology, cristae number and membrane rupture pres- ented an upward order of low-temperature low-humidity flue-curing process 〈 moderate-temperature high-humidity flue-curlng process 〈 moderate-temperature moderate-humidity flue-curing process. In low-temperature low-humldity flue-curing process, starch granules in chloroplasts ruptured after flue-curing for 36 -48 h ; in moderate-temperature moderate-humidity flue-curing process, starch granules in chloroplasts ruptured after flue-curing for 24 - 36 h; in moderate-temperature high-humidity flue-curing process, starch granules in chloroplasts ruptured after flue-curing for 12 - 24 h. [ Conclusion ] Using low-temperature low-humidity flue- curing technology could prolong the maintenance duration of the submicroscopic structure integrity of flue-cured tobacco leaves, which was conducive to fully decom- posing and transforming substances in tobacco leaves and obtaining high-quality flue-cured tobacco leaves.

The Quality Difference of Tobacco Leaves Between Different Flue-curing Processes in Honghe Tobacco-growing Area

[Objectives] This study was conducted to compare the effects of different curing processes,in order to optimize the local supporting intensive fluecuring process.[Methods] A comparative experiment was carried out in Mile,Luxi and Jianshui on the four-layer tobacco-packed intensive curing process(K1)and the eight-point precise and intensive curing process(K2).[Results]The results showed that according to the appearance evaluation of the tobacco leaves,K1 was higher than K2 in respective scores of color,maturity,leaf structure and defects and the total score,while K1 equaled K2 in the scores of identity,oil content,chroma and length.The differences in respective scores of the two processes were not significant.According to the results of sensory evaluation,the two tobacco enterprises got different evaluation results of unblended cigarettes made of the middle leaves due to different raw material requirements of the enterprises by different processes.K1 was higher than K2 in the sensory evaluation of China Tobacco Yunnan Industrial Co.,Ltd.,while it was lower than K2 in that of China Tobacco Zhejiang Industrial Co.,Ltd.,and the difference in the total score between the two processes was significant.From the content of chemical components,in the conventional chemical component contents including total sugar,reducing sugar,chlorine and starch,K1 was higher than K2,while in the contents of potassium,total phytonine,total nitrogen and petroleum ether extract,K1 was lower than K2,but the differences were not significant.K1 was lower than K2 in the contents of neutral aroma components including ketones,alcohols,aldehydes,heterocyclics,neophytadiene and total content,while K1 was higher than K2 in the contents of esters,phenols,but the respective differences were not significant.Except the significant difference in the total score in the sensory evaluation of China Tobacco Zhejiang Industrial Co.,Ltd.,there were no significant differences in other items in the appearance evaluation,sensory evaluation and chemical composition of tobacco leaves between K1 and K2.[Conclusions] The supporting intensive curing process can be further optimized on the basis of this study.

Application of tobacco stems briquetting in tobacco flue-curing in rural area of China

To reduce the conventional energy consumption in rural area of China,tobacco stems briquetting(TSB)was used as fuel during the process of tobacco flue-curing,compared with honeycomb briquette(HB).Three fire furnaces with different heat exchangers using TSB were compared using the tobacco flue-curing.The results showed that the smog temperature of TSB was higher than that of HB,the efficiency of bio-fuel system with TSB was from 43.5%to 54%,while the efficiency of traditional fuel system was 51.5%.And the cost of tobacco flue-curing per hectare with TSB and HB was$750.0 and$1282.5,respectively.It is proved that TSB is an alternative choice using for the industry of tobacco flue-curing,and the improvement in the structure of fire furnace could optimize the process of tobacco flue-curing.

Effects of Different Chemical Fertilizer Reduction Techniques on Flue-cured Tobacco Production

[Objectives]This study was conducted to find out the most suitable special formula fertilizer for flue-cured tobacco production in tobacco-growing areas of Zhaotong City,so as to provide a basis for scientific fertilization and reduced application of inorganic fertilizers with improved efficiency in tobacco production in Zhaotong City.[Methods]Different formulas of special base fertilizer and special topdressing for tobacco were designed by optimizing and adjusting the application amounts and proportions of nitrogen,phosphorus,potassium and medium trace elements in fertilizer formulas,and the formulas of special base fertilizer and special topdressing for flue-cured tobacco production were selected through a field plot experiment.[Results]The combination of special base fertilizer and special topdressing was conducive to the early growth and rapid growth of tobacco plants under the condition of reduced fertilizer application,and the treatment using organic-inorganic compound fertilizer as the special base fertilizer was the most obvious,with an average growth period of two days increased.Compared with conventional fertilization,the yield,output value,average price,proportion of superior tobacco and proportion of medium and superior tobacco increased in the organic-inorganic compound fertilizer treatment,with the yield increasing by 5.96%,the output value increasing by 17.08%,the average price increasing by 10.49%,the proportion of superior tobacco increasing by 4.63%,and the proportion of medium and superior tobacco increasing by 2.44%.It was concluded from indexes including growth period,agronomic traits,disease incidence and economic traits,the fertilization mode of organic-inorganic compound fertilizer with the addition of trace elements(boron,magnesium and zinc)applied as the base fertilizer and nitrogen and potassium topdressing was most efficient and economic.[Conclusions]This study provides a basis for scientific fertilization and reduced application of inorganic fertilizers with improved efficiency in tobacco production in Zhaotong City.

Research on Soil Conservation and Improvement Technology in Zhaoyang District

The environment of tobacco-growing soil directly affects the yield and quality of tobacco leaves.In order to solve problems of tobacco-growing soil degradation,low organic matter content and unbalanced soil nutrient supply and promote sustainable and healthy development of tobacco production,this paper comprehensively discussed conservation and improvement techniques of tobacco-growing soil based on existing problems in Zhaoyang District,aiming to provide reference for tobacco-growing soil conservation.

Comparative Analysis on Chemical Components and Sensory Quality of Aging Flue-Cured Tobacco from Four Main Tobacco Areas of China

Complicated changes are happening during the aging process of flue-cured tobacco （FCT） and understanding of the changing components is of great significance in improving the quality,shortening aging time,and enhancing production and economic efficiency in tobacco industry.The aging samples of FCT from four main producing areas of China,i.e.,Yunnan,Sichuan,Hubei,and Dongbei,were used to study the changing rule of the components such as alkali,acid,and carbohydrate as well as the aroma and their relationship with sensory quality;and based on the correlation among the components and the sensory quality index,multivariable models were established to predict the aging quality.The results showed that the sensory quality of FCT increased steadily during the aging time,and at the same time,the acidic components （total organic acids,volatile acids） increased gradually,while the alkaline substances （nicotine,volatile alkali）,carbohydrate （total sugars,reducing sugar） and pH values showed a downward trend.Correlation analysis found that the sensory quality and pH values were negatively correlated （P0.05）,while the sensory quality with total organic acids and aroma were positively correlated.The optimal model for predicting the quality of FCT was y=56.75-0.63x12＋50.09x2-13.27x22,（y：sensory quality;x1：pH;x2：total organic acids）.The average predicating error was 1.04% with maximum predicating error of 2.89% and the accuracy rate of above 97%.

Characteristics of Potassium-Enriched, Flue-Cured Tobacco Genotype in Potassium Absorption, Accumulation, and In-Ward Potassium Currents of Root Cortex

This study was to investigate the main traits of potassium-enriched, flue-cured tobacco genotypes related to potassium absorption, accumulation, and in-ward potassium currents of the root cortex. Hydroponic methods, K^＋-depletion methods, and patch-clamp, whole-cell recordings were conducted to study the accumulation of dry matter and potassium in different organs, and to measure potassium absorption and dynamic and in-ward potassium currents in potassium-enriched, fluecured tobacco genotypes. The average dry weights of leaves and whole plant of potassium-enriched, flue-cured tobacco genotype ND202 were 10.20, and 14.85 g, respectively, higher than JYH （8.50 and 13.11 g, respectively） and NC2326 （8.39 and 12.72 g, respectively）, when potassium concentration in the solution ranged from 0.1 to 50 mmol L^-1. Potassium accumulation in the leaves of ND202 was 18.6% higher than JYH and 34% higher than NC2326 when potassium concentration in the solution was superior to 0.5 mmol L^-1. The Vmax （the maximum velocity） of ND202 was 118.11 lamol FW g^-1 h^-1, obviously higher than that of JYH （58.87 μmol FW g^-1 h^-1） and NC2326 （64.40 μmol FW g^-1 h^-1）. In the in-ward potassium currents, the absolute value of current density （pA/pF） of ND202 was 60, higher than that of JYH （50） and NC2326 （40）. Potassium concentration in leaves, Vmax, and in-ward potassium currents, could be used to screen potassium-enriched, flue-cured tobacco genotypes.

Proteomics Identification of Differentially Expressed Proteins Relevant for Nicotine Synthesis in Flue-Cured Tobacco Roots Before and After Decapitation

Nicotine is a secondary substance synthesized in tobacco roots. In flue-cured tobacco planting, tobacco decapitation is an effective practice to promote nicotine biosynthesis by regulation of the redistribution of total nitrogen amounts. However, proteins relevant to nicotine synthesis in tobacco roots has not been identified and characterized yet. It is important to explore the regulation of nicotine biosynthesis in tobacco roots. To identify the proteins relevant to nicotine synthesis, the protein patterns in roots of flue-cured tobacco （cv. K326） before and after decapitation were analyzed. In the present study, the protein patterns in roots of flue-cured tobacco were analyzed by two-dimensional electrophoresis （2-DE）, and the differentially-expressed spots were identified by matrix assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF-MS）. Paired comparison of 2-DE maps revealed 26 spots of differentially-expressed proteins in roots before and after decapitation. Furthermore, nine differentially-expressed spots were identified. There were four proteins which were enzymes possibly involved in nicotine biosynthesis. In addition, the roles of the four enzymes in nicotine biosynthesis were discussed in a putative network. Our results would contribute to the understanding of the regulation pathway of nicotine biosynthesis and further to the molecular manipulation on the nicotine contents in flue-cured tobacco.

Relationship Between Hyperspectral Parameters and Physiological and Biochemical Indexes of Flue-Cured Tobacco Leaves

The experiment was set up for examining the physiological and biological indexes quickly and exactly, for obtaining information of tobacco-field fertilizing and tobacco growing. The ASD Field spec FR 2500 was used to measure spectra reflectance of flue-cured tobacco and the relationship between hyperspectral parameters and biochemical contents （total nitrogen, chlorophyll, carotenoid）, and physiological indexes （fresh weight, dry weight, moisture content） of flue-cured tobacco leaves was studied by correlation and stepwise regression statistic methods at different nitrogen and potassium levels. The results indicated that the spectra curves of different treatments had obvious rules and great diversities. There were high correlations between different types of spectra parameters and ten physiological and biochemical indexes of flue-cured tobacco leaves. Hyperspectral characteristic variables of ten physiological and biochemical indexes were found through stepwise regression, and SDr/SDb was the characteristic variable closest to seven biochemical contents. Simultaneously, the R2 and regression coefficient of equations reached 0.05 significant level and the equations had good estimating effects through the examination of other samples. Accordingly, this study suggested that the ten physiological and biochemical indexes could be estimated quickly by the estimating models, at the same time nitrogen-potassium fertilization and growth condition of flue-cured tobacco could be inspected.

Risk Regionalization of Drought for Flue-cured Tobacco Planting in Qujing City Based on GIS

The risk regionalization of drought for flue-cured tobacco planting in Qujing City was studied to provide reference for drawing on advantages and avoiding disadvantages in flue-cured tobacco planting,disaster reduction,and disaster relief services.According to the production practice of flue-cured tobacco and local climate analysis,the risk of disaster-causing factors,sensitivity of disaster-breeding environment,vulnerability of carriers,and disaster prevention and reduction capability were analyzed and evaluated quantitatively.Secondly,starting from the formation mechanism of drought,a risk assessment model of the meteorological disaster was established by GIS technology.Finally,the risk assessment and regionalization of drought in the critical periods for drought-stricken flue-cured tobacco (transplanting period,root extending stage and vigorous growth period) in Qujing City were carried out.The results showed that in Qujing City,the risk areas of drought for flue-cured tobacco planting were divided into five grades in the transplanting period and six grades in the root extending stage and vigorous growth period.

Effect of Different Intercropping Methods on the Reduction of Heavy Metal Content in Flue-Cured Tobacco

Heavy metals not only adversely affect the quality of tobacco leaves,but also have very adverse effects on human health. In order to find out the effective cultivation method of controlling heavy metal content in flue-cured tobacco,the content of four kinds of heavy metals in soil and tobacco leaves in different intercropping treatments was tested. The results showed that there were significant differences between the effects of intercropping on the content of some heavy metals in soil and tobacco leaves. Different interplanting methods had a positive effect on the reduction of heavy metal content in tobacco leaves and play a very important and positive role in actual production.

Effects of Amount of Green Manure Returned to Field on Yield and Quality of Flue-cured Tobacco

The effects of amount of green manure returned to field on yield and quality of flue-cured tobacco were studied by field experiment. The results showed that significant positive correlation existed between tobacco leaf yield and small or moderate amount of green manure returned to field. Path analysis showed that moderate amount of green manure returned to field affected yield and quality of tobacco leaves, small green manure returned to field mainly affected leaf yield, while large amount of green manure returned to field mainly affected leaf quality. Therefore, the effect of moderate amount of green manure returned to field on yield and quality of tobacco leaves was best, and moderate amount of green manure returned to field was recommended in production of flue-cured tobacco.

Effects of Organic Fertilizers on Tobacco Growth and Heavy Metal Contents in Flue-cured Tobacco

Pb, Cd and As are main heavy metal elements in tobacco leaves in China. Through the application of organic fertilizers in the tobacco area of Pu'er City, the effects on tobacco growth and heavy metal contents were investigated. The results showed that the tobacco plants in the treatments applied with organic fertilizers as the base fertilizer grew at a lower rate and had relatively smaller stem girth and leaf number than the treatment applied with the compound fertilizer special for tobacco in early growth period, and the differences between various treatments were not significant. After applying the organic fertilizers, they had a positive effect in reducing heavy metal contents of flue-cured tobacco, and the effect of applying oil cake was better, followed by the treatment of chicken manure plus oil cake. The sole application of chicken manure had a certain effect on the control of Hg, As and Pb, but the Cd content increased. For the areas with high heavy metal levels, the selection of appropriate organic fertilizers has a practical significance to the reduction of heavy metal contents in tobacco leaves.

Comparative Analysis of Climate Conditions and Adaptability of Flue-cured Tobacco Growing in Field in Enshi Prefecture

By the comparative analysis of climate conditions （ten-day average temperature, rainfall and sunshine hours） and physiological needs of flue-cured tobacco growing in field in Enshi Prefecture, it is found that precipitation is insufficient at the seedling stage but very sufficient in the maturation pedod, which has limited the production of high quality tobacco. To produce high quality tobacco in Enshi Prefecture, it is needed to breed middle and late varieties with longer growth period, improve current breeding methods to increase transplanting elasticity, water transported seedlings enough, and control diseases and insect pests.

Effects of N Application Rates and NO_3-N to NH_4-N Ratios on Yield and Quality of Flue-cured Tobacco Planted in Black Soil

A field experiment about effects of nitrogen application rates and different NO3-N to NH4-N ratios on agronomic, chemical and biological characteristics as well as yield and quality of flue-cured tobacco grown in a black soil was conducted from 2004 to 2005 in Heilongjiang Province. The results showed that the nitrogen application rates at 45 kg·hm^-2 with the ratio of 75% NO3-N to 25% NH4-N resulted in the highest potassium and reducing sugar contents in the flue-cured tobacco leaving with the highest quality grade and value. It is recommended that this ni- trogen application rate and NO3-N to NH4-N ratio should be widely applied on flue-cured tobacco grown in the black soil in Heilongjiang Province.

Canonical Correlation between the Leaf Quality Indicators of "Moderate Aroma" Flue-cured Tobacco

In order to find out the correlation between tobacco quality evaluation indicators in China's traditional " moderate aroma" tobaccoproducing areas and simplify the tobacco quality evaluation indicators,we evaluate the appearance quality and smoking quality of 143 flue-cured tobacco leaf samples in China's " moderate aroma" tobacco-producing areas,test the physical traits and chemical component,and analyze the canonical correlation between four quality evaluation indicators. The results show that there is significant or extremely significant canonical correlation between four evaluation indicators( tobacco smoking quality,chemical component,appearance quality and physical trait quality); the cumulative variance contribution rate of evaluation indicators is in the order of chemical component( 69. 17%) > appearance quality( 68. 76%) > physical traits( 64. 13%); appearance quality is most closely related to physical traits( 93. 84%). The individual indicators for tobacco quality evaluation make different contribution to the correlation between quality evaluation indicators. The chemical component evaluation indicators mainly include total sugar and ratio of total sugar to betaine; sensory taste indicators mainly include aroma volume,smoke concentration,irritation and softness degree; physical trait evaluation indicators mainly include leaf weight,leaf length and leaf density; appearance quality indicators mainly include leaf organizational structure,color,maturity and identity. Studies have shown that in the large-scale ecoregion,using canonical correlation analysis to simplify tobacco quality evaluation indicators is feasible.

Com parison of Amino Acids in Root Exudates of Flue-cured Tobacco Varieties with Different Resistances against Black Shank

In order to explore the differences of amino acids in root exudates and plant tissues, we selected four flue-cured tobacco varieties [ Yunyan 87 （ Ⅰ）, K326 （Ⅱ）, NC102（Ⅲ）, Hongda （Ⅳ）] as the test materials and studied the components and mass fractions of amino acids in rhizosphere soil, non rhizosphere soil, roots and leaves via high performance capillary zone electrophoresis. Ten amino acids were detected out from four varieties, including histidine, lysine, tryptophan, phenylalanine, valine, threonine, proline, serine, alanine and glycine. The mass fractions of amino acids in leaves and roots were higher than those in rhizosphere soil and non rhizosphere soil. In rhizosphere soil and non-rhizosphere soil, the mass fractions of lysine, phenylalanine, threonine, proline and glycine in susceptible varieties （ Ⅲ, Ⅳ） were higher than those in resistant varieties （ Ⅰ, Ⅱ）. In rhizosphere soil, the total amino acids successively were Ⅳ 〉 Ⅲ 〉 Ⅰ 〉 Ⅱ, and in non rhi- zosphere soil were Ⅲ 〉 Ⅳ 〉 Ⅰ 〉 Ⅱ. The total amino acids in roots of variety Ⅳ was the highest, up to 6 359. 195 μg/g. In leaves, the total amino acids in varieties I and If were higher than those in varieties IfI and IV. The results indicated that amino acids could secrete to rhizosphere via root secretion, and the compositions and mass fractions of amino acids varied with flue-cured tobacco varieties, thus the secretion amount of susceptible varieties was higher than that of resistant varieties.