Study On The Effect Of Irrigation Water And Precipitation On The Chloride Content Of Flue-cured Tobacco And Chlorine Control Measures

Flue-cured tobacco can easily uptake chloride ions from the environment,but higher chloride ion content can affect the growth of the tobacco plant and reduce the quality of the tobacco,resulting in lower quality indicators such as combustibility and aroma and taste of the tobacco.More than 60 % of the chloride ions in tobacco plants come from the soil,and their chloride ion content basically varies with the chloride ion content in the soil.The high chloride content of soils in some tobacco areas in China has led to occasional exceedances of chloride levels in tobacco,which has a negative impact on quality tobacco production.There are many factors affecting the chloride ion content of tobacco leaves,among which soil and groundwater chloride ion exceedance is the main cause.Therefore,this study will monitor the soil and watering water dynamics in the test field to identify the trend of chloride ions in the soil and the influencing factors throughout the year,and design three different methods to explore the effectiveness of reducing chloride ion content through field cultivation and laboratory hydroponics.The following conclusions were obtained from the experiment:1.Soil chloride ion content and precipitation showed a significant negative correlation.In this experiment,four tobacco plots were selected in the test area,and soil and irrigation water samples were collected monthly to determine the chloride ion content,and the correlation between soil chloride content,irrigation water chloride content and precipitation was analyzed.Soil chloride ion content decreases with increasing precipitation;the amount of soil chloride ion content changes with increasing precipitation,the leaching effect increases with increasing precipitation,soil chloride ion loss becomes faster and soil chloride ion content decreases.2.Intercropping alfalfa in large fields can reduce the chloride ion content in soil,and the chloride reduction effect increases with the increase of intercropping density.In order to investigate the effect of different alfalfa intercropping methods on soil and tobacco leaf chloride ion content,in the experimental area with different alfalfa intercropping methods to grow tobacco,soil and tobacco samples were collected to determine the chloride ion content,and it was found that the three intercropping methods of alfalfa in the middle of five rows of tobacco planted with five rows of tobacco width,three rows of tobacco planted with three rows of tobacco width in the middle of tobacco,and tobacco planted with alfalfa in between the rows of tobacco were all lower than the control group soil and tobacco leaf chloride ion content.The comparison of the three intercropping methods showed that the denser the intercropping,the better the effect of chlorine reduction,with one row of tobacco intercropped with one row of alfalfa having the best effect of chlorine reduction.3.Anion exchange resin significantly reduced the chloride ion content in water.In order to reduce the chloride ion in irrigation water,different amounts of anion exchange resin were used to treat water containing different chloride ion concentrations,and the chloride ion concentrations were measured at different time periods,and it was found that the anion exchange resin could effectively reduce the chloride ion content in irrigation water,and the chloride reduction effect increased with the amount of resin added;when the anion exchange resin absorbed chloride ion to a certain extent,it would re-release the originally absorbed chloride ion.The amount of anion exchange resin absorbs the highest amount of chlorine ions between 40 and 60 minutes after it is added to the water.4.Zn ions could inhibit chloride ion uptake in different tobacco varieties,and there was a significant negative correlation between the chloride ion content in the lower part of the ground and the amount of Zn ions added.Studies on the chloride ion content of five common tobacco varieties,NC55,NC102,K326,China Tobacco 100 and Zhongchuan 208,with different Zn ion additions under hydroponic conditions showed that Zn ion could reduce chloride ion uptake in tobacco,and the chloride ion content of both above and below ground leaves showed a significant negative correlation with Zn ion additions,and the above ground was significantly more affected by Zn ion than the below ground;the above ground of NC102 variety was the most affected by Zn ion.The above-ground chloride ion content of NC102 variety was most affected by Zn ion,and the below-ground part of Zhongchuan 208 variety was most sensitive to the effect of Zn ion,and the linear relationship was relatively significant.