The Impact Of Different Amounts Of Potassium Sulphateon The Effectiveness Of Rhizosphere Nutrient And The Microflora Of The Flue-cured Tobacco

Potassium is an important quality element of the tobacco leaf. The level of potassium is commonly low in tobacco leaves in China. The chief measure for improving the level of potassium in tobacco leaves is to apply potassic fertilizer. And potassium sulphate is the primary potassic fertilizer. In order to study the impact of different amounts of potassium sulphate on the effectiveness of rhizosphere nutrient and the microflora of the flue-cured tobacco, an experiment was carried out in the Qingdao Experimental Farm of the Tobacco Research Institute of Chinese Academy of Agricultural Sciences in 2013, which consisted of five treatments: the Blank treatment, the control treatment and three treatments with different amounts of potassium sulphate applied. By means of measuring the dry weight of flue-cured tobacco and the content of nitrogen, phosphorus, potassium and sulfur, the impact of different amounts of potassium sulphate on growing of the flue-cured tobacco was studied; by measuring the p H and effective sulfur content of the rhizosphere soil and the extraradical soil, the impact of different amounts of potassium sulphate on the rhizosphere nutrient of flue-cured tobacco was studied; and by measuring the quantity and compositions of microorganism of the rhizosphere soil and the extraradical soil, the impact of different amounts of potassium sulphate on the rhizosphere microflora of flue-cured tobacco was studied. Specific results are as follows: 1. Applying potassic fertilizer obviously increases the dry weight of the root, stem and leaf of the flue-cured tobacco. Different amounts of potassium sulphate have more impacts on the dry weight of the leaf than that of the stem. The dry weight of the root is not impacted by the amounts of potassium sulphate. 2. Potassium sulphate with different dosages exerts little effect on the nitrogen accumulation of flue-cured tobacco root and stem. From vigorous growth stage to mature stage, the nitrogen accumulation of flue-cured tobacco root and stem increasingly grows. With the increasing dosage of potassium sulphate, the total nitrogen accumulation of the whole flue-cured tobacco is on the decline, the nitrogen content in mature tobacco leaves shows a declining curve, the potassium and sulfur content of flue-cured tobacco leaves in mature period increase. The using of potassium sulphate significantly reduces the phosphorus content of mature tobacco leaves. 3. The use of potassium sulphate obviously lowers the p H of the tobacco planting soil, but the different handling of application amount of potassium sulphate is not so striking. The p H of the extraradical soil is lower than that of the rhizosphere soil. Along with the growth of flue-cured tobacco, the p H of rhizosphere soil gradually increases. Raising application amount of potassium sulphate can increase the available sulfur content and quick-acting potassium content in the soil, while application amount of potassium sulphate affects not much on the available sulfur content in the soil. 4. The way of using potassium sulphate increases the bacteria number in the rhizosphere soil while decreases the bacteria number in the surface soil; However, different quantity of potassium sulphate has no obvious effect on the number of funguses in soil. The number of funguses in rhizosphere soil and soil out of roots in mature period>fast growing period>rosette period. The use of potassium sulfate will reduce the number of actinomycetes in the soil around and out the rhizosphere. The potassium sulfate may have the ability to inhibit the growth of the actinomycetes. 5. With the dosage increase of the potassium sulfate, the diversity of soil microorganism is increased. The variety of microorganism in the rhizosphere soil is larger than that of the extraradical soil. That is, in the tobacco-planting soil, the microorganism mainly includes Proteobacteria and Actinobacteria, in which the Proteobacteria is divided into Alpha-proteobacteria and Beta-proteobacteria. The Proteobacteria is the advantaged flora in the tobacco-planting soil.