Study On Environment And Fertilization Effect On High Quality Sun-cured Daning Tobacco

Sun-cured Daning tobacco produced in Daning town of Hezhou city in Guangxi province is not only an important special germplasm resource in China but also a special high-quality raw material of cigarette production. But the requirement of massing production of Daning tobacco is limited by its low yield and the traditional backward "slash-and-bum" cultivation mode. So estimating the formed environment and analying the chemical composition of tobacco and testing fertilizer effect are basises for using high quality variety resources of Daning Tobacco. Ecological basis for Daning tobacco quality formation and its traditional planting technology were summarized by investigating the natural environment of Daning sun-cured tobacco and cultivation model. Effects of fertilization on growth, photosynthesis and sun-cured tobacco chemical compositions in Daning tobacco were further investigated by field experiments and frame-culivation experiments. The results were shown as follows:1、Easy to drainage and larger loping mountain environment may be in favour of the quality formation of Daning tobacco. Daning tobacco were cultivated traditionally in non-shady slopes with slope9°-51°, azimuth angle18°-262°, height above sea level ranged from430m to650m in Daning town. It is no special requirements in climate, landform and vegetation.2、Daning tobacco planting soils were characteristed by rich organic matter and shallow soil layer. Daning tobacco was planted traditionally in red soil derived from shale. The soils were characterized for strong acid with lower pH ranged from4.06to4.55. rich for organic matter (29.67-48.97mg/kg), nitrogen (N0.1521-1.935mg/k, available nitrogen153.0-224.9mg/kg) and boron (0.4073-1.762mg/kg) moderated potassium (59.44-106.0mg/kg) content of medium, but deficiency for phosphorus and shallow soil layer. Most of the topsoil was less than10cm with available phosphorus ranged from3.1mg/kg to19.8mg/kg and an average of them only6mg/kg.3、"Slash-and-burn" organic cultivation is the characteristics of Daning tobacco’s cultivation. In general, fertilization method was like follows:manure50-75g/plant and transplanting in late March to early May, spacing of50cmx70cm, planting density in2-3plant/m2. During15to30days after planting chicken chase manure application75-100g/plant, bran from seed tung tree fertilizer50-60g/plant, plant ash fire soil200-500g/plant.4、The chemical composition characteristics of Daning tobacco leaves are distinctive. Tobacco mature leaves with short stem harvesting and sun-curing. The sun-cured tobacco nicotine content was extremely low (0.42%-1.27%), which was relative to11.0%to84.0%of those in other tobacco including Zhangcun tobacco, Gonghui tobacco and Yunyan87. However, the content of crude protein (3.45%-4.95%) in Daning tobacco was higher than other Sun-cured Tobacco. Therefore, Daning tobacco has the characteristics of the high ratio of nitrogen to nicotine and the high ratio of sugar to nicotine, the ratio of nitrogen to nicotine in the upper leaves (2.07) is5times than other tobacco and sugar-nicotine ratio (65.73) is8times higher than other tobacco.The feature of lower nicotine, higher protein, higher sugar alkali ratio is more prominents in upper leaves. However, water soluble sugar distribution was uniform in Daning tobacco, with different leaf soluble sugar and reducing sugar content had little difference.5、It seem to unnecessary for Daning tobacco to grow in the original and specific soil for high qulity tobacco. The indexes including physiological indexes of photosynthesis, plant growth and tobacco smoking quality components did not differ significantly between the control and the treatment replaced other soil with low fertility level.6、Application of N15-45kg/ha, K2O90-270kg/ha as potassium nitrate and plant ash in addition to traditional organic fertilizer resulted in promotion of plant growth but did not decreased the quality of Daning tobacco. Addiction.of fertilizer to paddy soil after planting was benefited tobacco growth and improvement of quantity. On the other hand, the application of potassium fertilizer resulted in lower nicotine, and higher soluble sugar in flue-cured tobacco.