Analysis of ecological factors and quality of flue-cured tobacco leaves in Tongshan tobacco-growing areas

Basic conditions for tobacco-growing areas, meteorological factors, status of soil nutrients and quality of tobacco leaves were analyzed in Tongshan, Henan Province. The results indicated that: (1) Tongshan tobacco-growing areas had a long frost-free period, high accumulated temperature of ≥10℃, and a long period of time with daily average temperature of ≥20℃. The soil was yellowish-brown with a hilly topography, neutral to slightly acid pH, and low Cl~-1 content. (2) The stronger solar radiation, the longer sunshine hours and the more suitable precipitation could be the major climatic factors for Tongshan area to produce high quality tobacco leaves with rich aroma and taste. (3) The nutrient content of the soil showed a big variation in locations. The average contents were as follows: organic matter 1.13%, total N 0.084%, available N 85.22mg/kg, NH_4-N 9.55mg/kg, total P 0.033%, available P 11.66mg/kg, total K 1.73%, available K 132.85mg/kg, exchangeable Ca 2127.21 mg/kg, exchangeable Mg 391.55mg/kg, available S 50.24mg/kg, water soluble Cl 26.73mg/kg, available Fe 30.38mg/kg, available Mn 24.66mg/kg, available Zn 1.83mg/kg, available Cu 1.22mg/kg, available Mo 0.026mg/kg and available B 0.32mg/kg. The contents of organic matter, total N and available N were rich in general; the content of available P was rich for half of the soil samples, and poor for the other half; the content of available K was medium to low for most soil samples; the contents of most medium-micro elements were rich. But the ratio of Ca to Mg and the ratio of K to Ca in soil were not balanced, which decreased the absorption to Mg and K. In addition, the contents of available Mo and available B were obviously low, and it was suggested to add B and Mo for balanced fertilization. (4) Tongshan tobacco leaves had distinguishing features of high appearance quality with orange color, reasonable chemical constituents, rich flavor, and good sensory evaluation.