The Relationship Between Ecological Factors And Quality Of Flue-cured Tobacco Leaves In Shandong Tobacco Growing Regions

Shandong Province is one of the most important producing areas of high quality flue-cured tobacco in China. To explore the relationships between quality of flue-cured tobacco leaves and ecological factors such as soil and climate, in this study, soil samples, flue-cured tobacco samples with grades of C3F and climate data of 23 years from 169 counties, which are representative in flue-cured tobacco -growing areas, were used as the study subjects. The research methods included field survey sampling, chemical analysis, sense evaluation, modern mathematical statistics, and others. The conditions about soil nutrition, climate characteristics, the quality characteristics of flue-cured tobacco, and the effect of ecological factors on the quality of flue-cured tobacco leaves were studied. This research provides theoretical guidance for the high quality of flue-cured tobacco production and tobacco planting division. The main results showed as follows.The chemical component contents of flue-cured tobacco leaves in Shandong Province were appropriate to high quality cigarette production except reducing sugar, total sugar, and manganese, which were a little bit high. From the results of the score of smoking quality of tobacco leaves, the leaves produced in Shandong were characterized by their mild flavor, middle impact, taste concentration of middle to dense, good quality of aroma, fullness volume of aroma, comfortable after taste, lighter undesirable taste, slightly irritancy, middle of combustibility and ash of grey.The average soil organic matter content of tobacco-growing regions was 0.7%, which was relatively low in Shandong. The average pH value of tobacco-growing soils was 6.84. The average content of total nitrogen and available nitrogen were 0.078% and 57.11mg/kg, respectively, which were in the state of moderate or lack in most tobacco-growing soils. The average soil total phosphorus and available phosphorus contents were 0.049 % and 16.48 mg/kg, which varied largely. The soil total potassium and available potassium contents were high, with the average value of 3.29% and 173.84 mg/kg. Soil soluble chlorine content, in most of cases, was in the appropriate range, with an average of 21.2 mg/kg. The exchangeable calcium and magnesium contents were 14.02 cmol/kg and 4.09cmol/kg, which were sufficient to tobacco growth. The distribution of available iron in soil in tobacco growing areas varied largely with an average of 14.47 mg/kg, About 14.64% of the total samples were lightly available iron insufficient and 22.99% were extremely insufficient. The distribution of available manganese in soil in tobacco growing areas varied largely, with an average of 17.68 mg/kg, some areas were slightly lack of available manganese. The available zinc content of tobacco-growing soils in average was 0.83 mg/kg. Some areas were lack of available zinc, about 13.12% of the samples were slightly lack of available zinc and 0.33% samples of the total samples were extremely lack of available zinc. The available boron content of tobacco-growing soils was 0.615 mg/kg. Some areas were lack of available boron, about 25.16% of the total samples were slightly lack of available boron and 0.65% of the total samples were extremely lack of available boron. The contents of soil available molybdenum and available copper in Shandong tobacco-growing areas were sufficient. In Shandong tobacco growing regions,during field periods, sunshine hours are 890.85h, average temperature are 23.3℃,and precipitation are 514.2 mm. These regions have reasonable temperature and abundant precipitation resource during field periods. Sunlight hours are sufficient to the growth and development of flue-cured tobacco, however, there exist large space and time distribution variations for precipitation.The main soil types in Shandong tobacco growing regions are burozem, drab soil, skeleton soil, chao soil, shajiang black soil, lithosoil, and red clay soil, including 19 subgroups, 36 soil genus. Soil type play a great roles to Shandong tobacco leaf quality. Calcareous cinnamon soil, calcareous hapludent, and calcareous leached cinnamon soil can produce better quality tobacco leaves, but non-calcaric fluvisol usually produce poor quality tobacco leaves.It was the soil pH, organic matter, available nitrogen, available phosphorus, available potassium, total nitrogen, total potassium, water-soluble chloride, available iron, available manganese, exchangeable magnesium that largely influenced chemical composition of flue-cured tobacco leaves. The chemical composition of flue-cured tobacco leaf that affected by soil nutrition included total sugar, total nitrogen, protein, chlorine, the ratios of reducing sugar to protein, copper, iron, manganese, zinc, calcium, magnesium and phosphorus. The total alkaloid of tobacco leaf were less affected by soil nutrition of pre-fertilization. The smoking quality of tobacco leaf could improve with the increase of organic matter, total phosphorus, total potassium and available iron content in soil, and declined with the increase of available nitrogen and water-soluble chloride, available phosphorus and available manganese content in soil. But there was the irritation decreasing trend with increase of the available manganese content in soils.Reducing sugar, total nitrogen, total alkaloid, protein, iron, calcium and phosphorus were influenced by the number of sunshine hours, the average temperature and precipitation in May, the average relative humidity in July. Aroma quality,aroma quantity, offensive taste, taste concentration and after taste were influenced by precipitation, sunshine hours and the temperature in May, the temperature and the average relative humidity in June, and sunshine hours in July. The content of reducing sugar, total sugar, potassium, and the ratios of total sugar to nicotine, and the ratios of reducing sugar to protein were positively related to precipitation of May and August. The protein, volatile bases, and phosphorus were negatively related to it. The total alkaloid was negatively related to precipitation from May to August. Aroma type change from middle partial to enriched to middle, or from middle partial to enriched or middle to middle partial to freshly with increased precipitation during May and August. There are improving trend of smoking quality of tobacco leaf with increase of precipitation during field periods in Shandong tobacco growing regions.