Effects Of Soil And Climate And Its Interaction On Quality Of Flue-cured Tobacco In Hunan High-quality Tobacco Regions

Soil and climate are the main ecological factors that affect the quality of flue-cured tobacco (Nicotiana tabacum). All three typical tobacco regions, which locate in northwestern, southern and middle part of Hunan province, with different soil and climatic conditions are among the important regions with characteristic high-quality tobacco in China, but there are slight differences of quality of tobacco leaf among them. To enhance the research on the relationship between tobacco quality and soil or climatic factors and especially to clarify which is the key ecological factors in affecting the quality of flue-cured tobacco from soil or climate are of great significance on doing better in the regionalization and production technology system of flue-cured tobacco, further improving the quality of tobacco leaves and promoting sustainable development of tobacco industry in Hunan. Therefore, the influences on 17 quality indexes of flue-cured tobacco in Hunan high-quality tobacco regions were talked about by soil, climate and its interaction in 2006-2007 years with pot experiment method by using native soil and imported soil at each trial point which are in Sangzhi, Yongzhou and Liuyang county which representing three tobacco regions above in Hunan region, respectively. The main results are as follows:1. The influences of the climate factor under the same soil conditions on the physical properties, the color difference between opposite leaves, the main chemical components, the main volatile aroma components and sensory quality of tobacco leaves were greater than those of the soil factor under the same climatic conditions. And there were some influences of the interaction of soil and climate on the above quality indexes of tobacco leaves.2. The analysis by partial ETa2 value indicated that the influences of the climate factor on the flue-cured tobacco quality in Hunan region were strongest, followed of the interaction of soil and climate. The influences of the soil factor were least significant. The contribution to total variation rate of flue-cured tobacco quality caused by the climate, the soil and its interaction in Hunan region were followed as 52.4%, 17.2% and 30.4%, respectively.3. The analysis by gray correlation degree showed that the sub--cological factors which are closely relative to different quality properties of tobacco leaves in Hunan were different. The main sub-ecological factors which were related closely to the physical properties of tobacco leaves were 10cm ground temperature, quantity of solar radiation and diurnal temperature variance at rooting stage,10cm ground temperature both at vigorous growth stage and mature stage, etc. Those to the color difference between opposite tobacco leaves were quantity of evaporation at rooting stage, diurnal temperature variance, quantity of evaporation and sunshine hours at vigorous growth stage, quantity of evaporation at mature stage, etc. Those to the main chemical components of tobacco leaves were sunshine hours and quantity of evaporation at rooting stage, diurnal temperature variance and relative humidity at mature stage as well as available potassium in soil, etc. And those to the main volatile aroma substances of tobacco leaves were diurnal temperature variance and air pressure at vigorous growth stage, air pressure, quantity of solar radiation and air temperature at mature stage as well as available iron and available copper in soil, and so on.4. It was obvious that the greatest strength on the flue-cured tobacco quality in Hunan high-quality tobacco regions was by climate factor, next was by the interaction between soil and climate, the last was by soil factor. In a word, climate was the main factor that impacted on the quality of flue-cured tobacco in Hunan high-quality tobacco regions. So the influences on the tobacco quality of local ecological conditions, especially climate factor, should be fully taken account of in making the regionalization of Hunan tobacco perfectly and in establishing tobacco production technology projects.