| Guizhou Province is one of the best areas for flue-cured tobacco growing, and also one of the most important producing areas of high quality flue-cured tobacco in China. As one of the main industries for Guizhou Province, the taxes from flue-cured tobacco industry makes almost 1/4 to 1/3 of the provincial revenue, and also contributes almost more than 60% of the income for tobacco producing fanners.There are almost 20×104hm2 of the acreage and 33.3×104t of the yield in average for tobacco producing in Guizhou Province, both of which rank No.2 in all China. So the quality and quantity of tobacco producing makes important role in economic and society development for Guizhou Province and also for tobacco industry development in China. In the long term, the studies on flue-cured tobacco in Guizhou Province were focus on chemical elements of nitrogen, phosphorus and potassium, but never systematical studies on the relationship between the nutrition environment of the planting area and the quality of the tobacco leaf, which results in lack of critical theoretic guidance on nutrition management and tobacco growing process. From now on, most of the relevant research on relationship between tobacco leaf's chemical elements and its quality in the whole country were lack of a most important regional perspective, just as county, city and provincial area. At the same time, the chemical indicators in one regional scale research are also not enough.Therefore, this research will mainly focus on the relationship between the nutrition environment and the quality of tobacco leaf with the comparative of different areas in Guizhou Province. According to the research, the basic characteristics of the relationship between nutrition environment and tobacco leaf's quality in tobacco planting area which located in Karst mountain areas in Guizhou Province would be found, and it also could supply scientific guidance for nutrition management and the quality appraise of the tobacco leaf.In the research, a total of 5120 soil samples (including 16 nutrients indicators), 699 tobacco leaf samples (including 15 chemical component indicators) and climatic data of 40 years from 38 counties, which are preponderant in flue-cure tobacco production in Guizhou Province, were used as the objects. The methods of research covered chemical analyzing, data statistical analyzing, and field experimenting. The characteristics about nutrition environment, tobacco leaf's quality and their mutual relationships were studied. Then the characteristics about nutrition environment and tobacco leaf's quality with different regional scales were deeply studied in order to explore the evaluation methods for tobacco leaf's quality with different scales. Finally, the summary and recommendations for nutrition management in high quality tobacco leaf's producing were been provided according to the characteristics of nutrition environment in tobacco-growing regions and the results of fields experiments. Following are the results of the research:1. Basic characteristics of nutrition environment in tobacco-growing regions of GuizhouFor the tobacco-growing soils, the content of organic matter in average was 28.41g·kg-1, of which the soil samples with suitable contents accounted for 59.5%. The total nitrogen content in average was 1.60g·kg-1 of which the samples with rich and moderate contented accounted for 91.8%. The content of organic matter and total nitrogen in most tobacco-growing soils are suitable for the production of high quality tobacco. There also some soils had higher contents of organic matter and total nitrogen, which fertilizers need to be controlled. The available phosphorus content in average was 17.72 mg·kg-1, of which the soil samples with most suitable contents accounted for 35.2%, and also 30.7% in more or much more contents. The available phosphorus had been accumulated noticeably, and the application rate of phosphate fertilizer should be reduced in the soils with rich phosphorus. The available potassium content in average was 139.65 mg·kg-1, of which the soil samples with suitable contents reached 25.3%, and also 63.9% of samples in lack or much lack contents. As the area of potassium not enough is large so that the emphasis must be given to the application of potash fertilizer to these soils. The contents of both exchangeable calcium and magnesium were rich, of which amounting to 4.51cmol·kg-1 and 1.03cmol·kg-1 respectively, and the proportion of the contents from middle to rich values accounted for 83.2% and 77.2% respectively. The contents of available sulfur were the highest among the tobacco-growing soils in southern China with the average value of 43.39mg·kg-1. It is better that the ammonium phosphate and concentrated superphosphate should be chosen as basal fertilizers in order to avoid excessive phosphorus being brought to the soils though the fertilization. The available iron, manganese, zinc and copper contents in average were 37.40 mg·kg-1, 45.85 mg·kg-1, 1.62 mg·kg-1 and 1.86 mg·kg-1 respectively, and the sampled soils of zinc and copper with less than the critical values reached 21.4% and 21.0% respectively. The available boron was in rather deficit with an average of 0.35mg·kg-1, of which about 84.3% were less than the critical value, so it is inadequate for the tobacco production and boron fertilizer should be added in the compound fertilizer for tobacco. Too low contents of water-dissolving chloride have become the major limiting factor that influencing the tobacco quality in Guizhou. The contents of water-dissolving chloride were so low as in average of 7.04mg·kg-1, of which 98.0% of them were less than 30 mg·kg-1 of the suitable chloride content that stipulated by Tobacco Plant Region Distribution. In this context, the potassium sulphate of which the potassium rate is 30% might be replaced by potassium chloride in order to obtain the effects of increasing chloride and decreasing sulfur. The most suitable soil lands for high quality tobacco leaf's growing almost accounted for 62.1% of which the soil lands were light acid or neutron that the pH values varied from 4.19 to 8.83.For the middle part of tobacco leaf, the total nitrogen content in average was 1.75%, of which the suitable samples accounted for 74.2% although there were also parts of leaf were lack in nitrogen nutrition. The phosphorus content in average was 0.19%, of which the suitable samples accounted for 93.4% that means the tobacco leaf's quality had been improved obviously in phosphorus nutrition. The potassium oxide content in average was 2.42%, of which the suitable contents reached 46.0% compared with 32.0% were lower content which means the tobacco leaf were not enough in potassium nutrition. The contents of calcium and magnesium in average were 2.75% and 0.42% respectively, of which the suitable samples were 73.5% and 67.6% respectively. The sulfur content in average was 0.43%, of which the suitable leaf samples accounted for 83.8%, and there also had parts of tobacco leaf were excessive in sulfur nutrition, which resulted in coarse texture and dark leaf color after green leaf flue-curing. The chloride content in average was 0.19%, of which the suitable samples accounted for 12.4%, and also 82.0% in contents less than 0.3mg·kg-1. Lack of enough chloride elements in tobacco leaf has become another major factor that limiting the tobacco quality in Guizhou. The boron, zinc and copper contents in average were 34.03mg·kg-1, 45.20 mg·kg-1 and 8.60 mg·kg-1 respectively, of which the suitable samples accounted for 58.0%, 81.9 % and 32.9% respectively.2. Characteristics of nutrition environment for tobacco planting regions with different scalesIn average, the nutrition levels of the tobacco planting soil and the quality of the leaf were much different in different regional scales. For example, the distribution scale of nutrition level was quite big in county scale. But in regional or city scale, the difference between the soil nutrients and tobacco mineral nutrients became small with the regional scale more and larger. An inverse ratio between the nutrition contents level and regional scale was been found. With the provincial scale which covers the broadest geographical area, and almost all environment conditions and management ways, there had biggest change in nutrition contents. In regional or city scale, with the difference between the environmental and management condition compared with provincial scale, the changeable was becoming small. In a county scale, the changeable was the smallest with almost the same environmental and management condition. There were big differences between different regional scales and distribution of nutrition in tobacco leaf, of which the biggest variable was in county scale compared with the smallest in regional scale.The nutrition distribution of soil and tobacco leaf could briefly represent the basic conditions of the nutrition environment in different regional scale which also could provide a proof for nutrition management and decision making.3. Basic characteristics of tobacco leaf's quality in GuizhouFor the quality of middle part of tobacco leaves, the contents of total nitrogen and protein in average were 1.75% and 7.49% respectively, which were the best among indicators of tobacco leaf's quality, of which the suitable samples accounted for74.2% and 74.8% respectively. The contents of total sugar and reducing sugar in average were 27.36% and 24.02% respectively, which were better among the indicators, of which the suitable samples accounted for 58.6% and 66.2% respectively. Both of the contents of starch and nicotine were rather bad, averaging 5.04% and 2.70% respectively, of which the suitable samples accounted for only 36.9% and 35.2% respectively. The harmony of quality indexes of tobacco leaf should be improved in the future. For example, the Shmuk values were rather high, which in average was 3.92, of which the suitable samples accounted for 6.4%, meaning the ratio of total sugar to protein were not in harmony. The ratio of total nitrogen to nicotine was low that in average was 0.70, of which the suitable samples accounted for 20.3%. The ratio of reductive sugar to nicotine in average was 10.8, of which the suitable samples reached 21.3%, which resulted in gentle taste and tame aroma for parts of tobacco leaves. The ratio of potassium oxide to chloride was rather high that in average was 23.31 and the suitable samples accounted for 19.0%. The total scores for smoking ranged from 30.7 to 41.2 with the average score of 36.9.4. Characteristics of tobacco leaf's quality with different regional scalesThere were different in chemical components, the value of quality indicators and smoking quality of the tobacco leaf in different regional scale, of which had small difference in regional or city scale compared with large difference in county scale. At the county scale, major chemical components influencing leaf quality were rather similar, with the first principal component including total sugar, reductive sugar, nicotine, reductive sugar to nicotine ratio and total nitrogen to nicotine ratio. One or two principal components (or factors) could be used to represent tobacco leaf's quality. At the prefecture scale, the relationship became complicated between chemical components and leaf quality, and more chemical components were needed to represent leaf quality. At the provincial scale, the relationship was more complicated so that overall quality could be represented by using many more chemical components (including carbohydrates, compounds containing nitrogen, ratio and mineral nutrients). It was concluded that more chemical components were needed to evaluate tobacco leaf's quality at prefecture and provincial scales than at county scale.5. Relationship between nutrition environment and tobacco leaf's quality in tobacco-growing regions of GuizhouThe results of stepwise regression and canonical correlation analysis indicated that the leaf quality was correlated with different type of nutrients for tobacco-growing soils. The soil organic matter was significant negatively correlated with leaf total sugar, leaf reductive sugar, reductive sugar to nicotine ratio and copper, whereas positively with nitrogen-containing compounds, zinc and chloride. The nitrite nitrogen was significantly correlated with protein and starch, the ammonium nitrogen was significantly and negatively correlated with potassium oxide. There were significantly positive correlations between available phosphorus and total sugar, among available potassium, exchangeable calcium and starch, among water-dissolving chloride, total nitrogen and nicotine, and between pH and nicotine, whereas significantly negative correlation between available manganese and protein. There was close relationship between tobacco leaf mineral nutrients and tobacco leaf's quality. The total nitrogen was significant positively correlated with nitrogen-containing compounds, whereas negatively with carbohydrates. The significantly negative correlation was found between phosphorus and protein, whereas positive correlation among phosphorus and total sugar and reductive sugar. The potassium oxide was significant positively correlated with protein and total sugar, whereas negatively with nicotine. The calcium was significant negatively correlated with carbohydrates, whereas positively with nicotine. There were significantly negative correlations among chloride and total sugar and reductive sugar, and between zinc and starch.There were significant differences among smoking qualities of flue-cured tobacco leaf in three types of ecological regions. The order of ecological region suitable for tobacco growing was followed as: Ecological region II >Ecological region III>Ecological region I . For the ecological region I , the organic chemical components were influenced mainly by total nitrogen, phosphorus, potassium dioxide and magnesium, and also smoking quality mainly by total nitrogen, phosphorus, chloride, magnesium and potassium dioxide to chloride ratio. For the ecological region II, the organic chemical components were influenced mainly by total nitrogen, phosphorus, copper, chloride, boron and calcium, and also the smoking quality influenced mainly by total nitrogen, boron, chloride, potassium dioxide to chloride ratio, magnesium and zinc. For the ecological region III, the organic chemical components were influenced mainly by the total nitrogen, phosphorus, potassium dioxide and chloride, and also the smoking quality mainly by total nitrogen, sulfur, and calcium.6. Nutrition management for high quality tobacco leafAccording to the characteristics of nutrition environment of tobacco-growing regions and the results of field experiments, and also with the relevant researches in the past many years, the adjustment of nutrition management plan for three major nutrition for flue-cure tobacco production in Guizhou Province might be as follows: the rate of net nitrogen ranged from 90 kg·hm-2 to 112.5 kg·hm-2 in the dry cropland, and but from 75 to 97.5 kg·hm-2 in fertile paddy soils, and the better ratio of N to P2O5 to K2O was 1: 0.7- 1: 2-2.5. For the basal fertilizers, the proportion of nitrate nitrogen accounting for applied total nitrogen could range from 30% to 40%, and the rates of potassium from potassium chloride might reach 30% of the total rate of applied potassium, meanwhile, the ammonium phosphate and concentrate superphosphate were suitable type of phosphate fertilizers. The adaptive boron fertilizer could be mixed into specific fertilizer of tobacco. The nutrition management of tobacco should follow the principle of 'nitrogen-controlling, rational phosphorous, potassium-stabilizing, sulfur decreasing, chloride increasing and boron supplement'.
|
PDF Full Text Request