| The contents of chlorine in tobacco-planting soils and tobacco leaves, as well as the effect of different C1 application on the growth, nutrient absorbed and quality of tobacco were studied by investigation, field experiments and laboratory analysis in Chongqing. The purposes of this study were to understand the status of chlorine content in tobacco-planting soil and tobacco leaves, in order to provide detailed information for improving the quality of flue-cured tobacco leaves in Chongqing. The main results were as follows:The content of chlorine in various tobacco-planting soils was low, which average content was 13.4mg/kg with the range of trace to 99.7mg/kg in Chongqing. The chlorine contents in 90% of the soil samples were lower than 30mg/kg, which was very fit for tobacco planting. The chlorine contents in 3.7% of the soils were more than 45mg/kg and were not fit for tobacco planting according to the Handbook of Tobacco Planting Division. However, the chlorine contents in some soils were less than 2mg/kg that occupied 19.2% in the soils in the investigation regions, the chlorine was deficient, there were 50% chlorine potential deficient soils which chlorine content less than 10mg/lg. The yellow soil was a dominant tobacco planting soil, its proportion in the tobacco-planting soil accounts for 75.6% in Chongqing. The chlorine content in different soil types showed the order of yellow soil (15.2mg/kg) >lime soil (12.8mg/kg) >pale brown soil (5.6mg/kg)>purple soil (5.3mg/kg)>rice soil (1.8mg/kg).In the tobacco planting regions in Chongqing, the average chlorine content that was 2.6mg/kg in soil was the lowest in Fengdu and Shizhu county, the chlorine deficiency soils were in the proportion of 57.0% and 55.7%,respectively. The average content of chlorine in soil that was 5.8mg/kg was lower in Wulong county. In other counties, the chlorine content in soil was in the range of 10.0~22.0mg/kg.The content of chlorine in tobacco leaves was very low, which average content was 0.7g/kg with the range of 0.11g/kg to 9.19g/kg in Chongqing. The chlorine contents in 99% of the leaves samples were lower than 3.0mg/kg, which was the lower limit that demand of high quality tobacco leaves. The chlorine content in tobacco leaves were less than 0.25g/kg that occupied 19.2% in the investigation regions, the chlorine was deficient. The chlorine contents only 0.5% leaves samples were range 3.0g/kg to 6.0g/kg, which was the fit chlorine content of high quality tobacco leaves.Two years' results indicated that the proportion of first class tobacco leaves, the yield and the output value of tobacco raised with the increasing of chlorine application. There were decreasing trend of the quality indexes when chlorine application more than 60.0kg/hm2. Among all treatments, the growth status, yield, output value and the proportion of first class leaves of tobacco were the bestwhen application of 45.0mg/kg chlorine.The chlorine content of tobacco leaves raised with the increasing of chlorine application, which were straight line or index correlation. Under the condition of film-covering, leaves chlorine content of each part .which were 3.00~4.40g/kg ,was the best when the chlorine applied from 30.0~45.0mg/km2 in soil. But uncovered, leaves chlorine content of each part , which were 2.10~5.00g/kg, was moderate ,when the chlorine applied from 45.0~60.0mg/km2 in soil, when the chlorine applied less than 30.0mg/km2 in soil, the leaves chlorine content were lower than 3.00g/kg under the above two conditions. According the leaves chlorine content, the treatment of Cl application with 45.0mg/kg in soil was the best. The leaves chlorine content in different parts showed the order of upper>middle>lower. The leaves sulphur content decrease and the content of Ca, Mg, Fe, Mn, Cu and Zn of leaves increased with the application of chlorine fertilizer.The contents of total sugars and reduced sugars in the tobacco leaves were increased by application of proper chlorine, and decrease the content of nicotine and total nitrogen of upper as... |
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