Abstract:

To evaluate and screen out the best green manure crops suitable for crop rotation with flue-cured tobacco, four treatments were set up in the field test, including flue-cured tobacco and winter fallow, flue-cured tobacco and smooth vetch, flue-cured tobacco and radish and flue-cured tobacco and ryegrass, to explore the yield, output value, agronomic characters, chemical components of flue-cured tobacco and the nutrient content of the tobacco-growing soil. The results showed that different green manure rotations significantly increased the average price and output value of tobacco leaves. Among them, the average price of tobacco leaves in the rotation with smooth vetch, radish and ryegrass was increased by 15.37%, 20.04% and 17.72%, respectively, and the output value was increased by 23.6%, 24.1% and 18.3%, respectively, compared with those of the winter fallow treatment. The smooth vetch treatment increased the proportion of middle and upper class tobacco. The nicotine content, difference between total sugar and reducing sugar and the non-nicotine nitrogen/total nitrogen of the tobacco leaves in the smooth vetch and radish treatments all reached the level of high-quality tobacco leaves. In summary, the planting and utilizing of smooth vetch and radish could significantly increase the average price and output value of flue-cured tobacco, and make the chemical composition of tobacco be more harmonized and the chemical qualities meet the standards of high-quality tobacco. These green manure and flue-cured tobacco rotation systems are the effective methods to be promoted in Yunnan.

Key words: green manure, rotation, output value, quality of tobacco leaves, chemical composition