Simultaneous inoculating technology was used to mass rear Aphidius gifuensis.Results showed that a desirable rearing benefit could be achieved with the parasitical ratio of Aphidius gifuensis on tobacco aphids of 47% and inoculating 2.8 aphids per plant.The amount of aphids could reach 110 thousand aphids per square meters after 18 days of rearing,and the amount of stiff aphids could reach 4.9 thousand per square meters after 23 days of rearing.

Dali flue-cured tobacco plays an important role in formula of several core cigarette brands.Malic acid is one of major nonvolatile organic acids of tobacco leaf,and it is one of common aroma additives for high-grade cigarettes,so researchers highly focus on tobacco malic acid.The objective of the study was to investigate spatial distribution of malic acid content of Dali flue-cured tobacco,and to provide references for layout of tobacco planting and using of tobacco leaf.The main tobacco planting areas in Dali were selected as the experiment sites.200 flue-cured tobacco samples of C3F grade were collected from 100 sites in 2007 and 2008 via global position system(GPS).Malic acid contents of tobacco samples were determined.The mean value of tobacco malic acid content of samples in each site was regarded as the original data.The original data,data obtained after logarithmic transformation and Box-Cox transformation were tested for normal distribution.Surface trend and spatial distribution of tobacco malic acid content were analyzed by geostatistical analyst.The results showed that the data after logarithmic transformation showed normal distribution.The integrative comparisons of semi-variogram parameters of the ordinary kriging prediction with three trends and four theoretical models indicated that 1-order trend effect and exponential model were preferable.There were moderate spatial correlation and linear surface trend for tobacco malic acid content in Dali.Malic acid content of Dali tobacco ranged from 41.26 mg/g to 123.45 mg/g,the mean was 81.00 mg/g,and the range of background value was from 65.01mg/g to 80.00 mg/g.The growing areas with the highest malic acid content ranged from 100.01 mg/g to 124.45 mg/g were located in Nanjian county,Weishan county,and Midu county.In the southern tobacco growing areas of Dali,malic acid content showed gradient-like distribution with high-to-low trend from south to north.

Content of volatile and semi-volatile acid in flue-cured tobacco Yunyan 85 of different stalk position was studied by GC method.The test materials Yunyan 85 were collected from paddy soil and dry land of Binchuan County and Midu County in Yunnan province.Results showed that volatile and semi-volatile acid content in Midu County were higher than that in Binchuan County,among which 3-methyl valeric acid and benzoic acid showed clear difference.In adjacent pilot sites,content of most volatile and semi-volatile acids in dry land were higher than that in paddy soil,among which 3-methyvaleric,lauric and oleic acid showed notable difference.Content of volatile and semi-volatile acid in upper and middle leaves were higher than that of lower leaves,and this was not affected by tobacco growing areas and fields.

Flue-cured tobacco in Yunnan plays an important role in formula of Chinese cigarette.Polyphenol is one of the main aroma precursors in tobacco leaf,so researchers highly focus on polyphenol compound.The objective of the study was to investigate spatial distribution of polyphenol content in flue-cured tobacco in Yunnan,and to provide references for layout of tobacco planting and using of tobacco leaf.The tobacco planting areas in Yunnan were selected as the experiment sites.1 410 flue-cured tobacco samples of C3F grade in 2007 and 2008 were collected from 705 sites via Global Position System (GPS).Polyphenol contents of tobacco samples were determined,and the original data of tobacco polyphenol contents were taken from the samples mean in every site.The original data,data of logarithmic transformation and data of Box-Cox transformation were tested for normal distribution.Surface trend and spatial distribution of tobacco polyphenol content were analyzed by Geostatistics Analyst.The results showed that the data of logarithmic transformation showed normal distribution.The integrative comparisons of semi-variogram parameters of the ordinary kriging prediction with different trends and theoretical models indicated that 0-order trend effect and gaussian model were preferable.There was moderate spatial correlation (C0/C0+C=35.71%) and no surface trend (0-order)for tobacco polyphenol content in Yunnan.In most tobacco growing areas of Yunnan,the tobacco polyphenol content ranged from 3.50% to 4.00% (acted as background value).The growing areas that the polyphenol content was over 4.00% were mainly located in the west,centre and east of Yunnan.The growing areas that polyphenol content was over 4.50% were sporadically distributed in the areas,with polyphenols contents of 4.00-4.50%.Polyphenol content showed gradient-like distribution with high-to-low trend from center to surroundings in the growing areas.The areas with polyphenol contents of 5.50-6.73% were located in Nanjian county,the northern Yongping county,the north-west of Longling county and the western Wuding county,and the area in Nanjian county was the biggest one among them.

Using ripe middle leaves of flue-cured tobacco cv.Honghuadajinyuan as experimental material,the contents of nonvolatile organic acids,lignin,soluble sugar and nicotine in primary veins,primary lateral veins and secondary lateral veins of tobacco leaves were compared.The results showed that veins accounted for more than 60% of the dry weight of whole leaf;the contents of nonvolatile fatty acid,lignin,soluble sugar and nicotine in various leaf veins differed significantly,the veins in order of the contents of saturated fatty acids,unsaturated fatty acids,high fatty acid and nicotine were secondary lateral vein primary lateral vein primary vein,while the contents of dicarboxylic fatty acid and lignin were on the contrary;as for soluble sugar content,the order was primary vein secondary lateral vein primary lateral vein.

Take the Dali Bai Minority Autonomous Prefecture in Yunnan as an example,the influential factors on the flue-cured tobacco planting distribution were analyzed by using the principal components regression.The result indicates that,the planting area of average per household,the variety difference,the cost of production material on tobacco leaf,the labor force quantity and the output value of unit area are all the key factors which affects the flue-cured tobacco distribution in each tobacco planting area of Binchuan County,in the other hand it also reflects the problems about the dispersive planting,the high cost,the low benefit as well as to the high dependency on manpower in the traditional tobacco leaf production.Therefore,in order to layout flue-cured tobacco producing place scientifically,promote the transformation from traditional tobacco agriculture to the modern one and enhance the tobacco leaf income,the tobacco department should enhance the concentration ratio and mechanization level of tobacco leaf production,optimize the production link and increase the planting area in dominant variety region moderately.

The effects of nitrogen application and plant density on agronomic characters and output value of Hongda were studied in tobacco field,and the differences of light intensity and temperature in various groups were measured.The results showed that leaf area index was mainly affected by the nitrogen application rate,and plant density became more important with the lapse of growth stage.In rosette stage,light intensity at the base site of stem weakened with the increasing nitrogen application rate and plant density.Remarkable difference was found in the interaction effect of nitrogen application rate and plant density on sunlight of lower and middle tobacco plants.Temperature at different vertical height changed slowly with the increasing nitrogen application rate,and lower rate might result in dramatic changes.In vigorous growth stage,the highest temperature at 14:00 in tobacco fields appeared at the canopy,65 cm high from the ground,whereas at other times increased with the increasing vertical height.An increasing plant density could result in high output value at lower nitrogen level,while at high nitrogen level,it demonstrated the opposite,with declined tobacco quality.Comprehensively,the nitrogen application rate of 5 kg and plant population of 1 330 in 666.7 m2 might result in optimium output value.

In order to investigate the effect of fertilizer application on the effect of soil nitrogen and flue-cured tobacco leaf quality in Dali,Yunan province,field experiments were conducted with three treatments(control,chemical fertilizer,organic-inorganic fertilizer) on 5 representative soils in Dali.The result showed that red soil of Haihong had high fertility,thus fertilizer application was not required.Red yellow soil of Zuli,red sand soil of Xinsheng,purple oil of Bozhishu and red clay of Xiaoqiao needed to apply fertilizer to ensure tobacco growth.At the same fertilizer rate,the higher the soil available nitrogen,the higher the total nitrogen of tobacco leaves.Nitrogen supply was lower in the treatment of organic-inorganic fertilizer application at the 5 soils than chemical fertilizer treatment in early growth stage,but N deficiency was not observed for both treatments.For the soils with high available nitrogen and heavy texture,it is necessary to reduce nitrogen fertilizer application to ensure the yield and quality of tobacco.

A pot experiment was carried out to study the malic acid(0,1,2 and 3g/L) on nitrogen metabolism of flue?cured tobacco seedling after 20 d and 40 d transplantation.Three plants were collected from each treatment to test physiological characters and chemical components after 50 d transplantation.The result showed the appropriate amount of malic acid promoted the release of nitrogen in soil and accelerated the accumulation of nitrogen in plant.The root vitality was increased and nitrogen metabolism was strengthened with the increasing of malic acid concentration in terms of the promoted nitrate reductase activity,reduced content of nitrate nitrogen and the increased of content of ammonium nitrogen in root,while the quantity of nitrogen was reduced in terms of reduction of indicates that nitrate nitrogen and nitrate reductase.We can conclude that applying malic acid altered the status of the nitrogen metabolism in the leaf and root. It could increase the proportion of reduction and assimilation in the root and decrease the proportion of reduction in the leaf.In general,malic acid application promoted the nitrogen metabolism of flue-cured tobacco.

This study investigated the effect of soil nitrogen regulator on soil available nitrogen.The lab test results showed that application of soil nitrogen regulator decreased soil available nitrogen content significantly,which decreased 19.81 mg / kg 25 days after application.Field experiment indicated that nitrogen regulator applied after topping could decrease dramatically alkaloid content,increase yield output and ratio of middle-upper class,and improve leaf appearance and quality.The best result was observed on treatment with 1500 kg / ha+microorganism II.

For improving the germination percentage and uniformity of seedlings, the pelleted germinating seeds of fluecured tobacco were experimented. The results showed that the germinating viability and germination percentage of pelleted germinating seeds were increased by 21.7-35.8 and 3.2-9.2 percentage points than that of normal pelleted seeds, respectively. The seedling emergence time of pelleted germinating seeds was 5-7days ahead of normal pelleted seeds in Dali tobacco growing areas, and the growth vigor and uniformity of seedlings in beds and fields were better than those of normal pelleted seeds.

The causes of salinization of medium and its effects on seedling\|growing in float system were studied. The results showed that the degree of salinization of medium was closely related to the temperature, humidity and electroconductivity (EC) of medium during seedling growing process; salinization resulted in low emergence and seedling rate and poor seedling quality. The effects of the salinization of medium could be effectively decreased by reducing the content of salts in medium and keeping the EC(25℃) of its saturation extract ≤1160μs/cm.