Ecological Characteristics Evaluation Of Flue-cured Tobacco Planting In Jiaxian County

Jiaxian County is one of the four major sources of flue-cured tobacco in China,and is one of the core producing areas of strong-flavor tobacco.This study took the climate characteristics and soil chemical compositions of Jiaxian County as the research object and integrated the chemical composition of tobacco leaves to build the ecological suitability division of Jiaxian tobacco area,in order to provide reference for optimizing the layout of Jiaxian tobacco area and promoting the development of high quality tobacco leaves.The main results are summarized as follows:1.Established the suitability evaluation system of tobacco-growing soil in Jiaxian County.The soil p H,content of organic matter,alkali-hydrolyzable nitrogen,available phosphorus,available potassium and water-soluble chlorine were determined by expert scoring method(Delphi method).The evaluation weights of the above indexes were 0.0422,0.2564,0.2564,0.0943,0.2564,0.0943 by analytic hierarchy process.2.The climatic characteristics and changing trend of the field period and each growth stage from 2001 to 2020 were analyzed.The average temperature during the field growing period was 23.08℃,showing an overall upward trend.The average days of field growing period ≥20℃ were 112 days.The average sunshine hours in the field growing period was1132.70 h,the annual average rainfall during the field growing period was 485.65 mm,the average relative humidity of the field growing period in Jiaxian County was 71.76%,and the average ground temperature at 10 cm was 24.73℃.The average temperature of root extending period,vigorous growing period and mature period(the same below)was 21.66℃,26.29℃ and 25.43℃;The average sunshine hours were 214.90 h,196.57 h and 466.86h;The average rainfall of each growing period was 55.25 mm,76.65 mm and 301.25 mm,the rainfall of root extending period and vigorous growing period was less than common,and the rainfall at mature period was more than common;The average relative humidity of each growing period was 64.03%,63.93% and 79.39%,the early stage was low,and the later stage was high;The ground temperature at 10 cm was 22.88℃,27.32℃ and 27.66℃.The average temperature,sunshine hours,average relative humidity and 10 cm ground temperature in the field growing period of Jiaxian County were generally suitable,which could meet the needs of high-quality tobacco production.Irrigation should be strengthened for insufficient rainfall and the low average relative humidity in the early growing period,besides,drainage and water conservancy facilities should be strengthened for excessive rainfall in the later growing period.3.The suitability of soil chemical composition was evaluated and divided.The average p H of tobacco-growing soil in Jiaxian County was 7.70,and 86.99% of the soil had high p H(>7,which was at the neutral and alkaline level.The soil p H in Likou,Tangjie and Yaozhuang townships was relatively suitable,and the rest of the townships were higher.The content of soil organic matter was rich,with an average value of 16.22g/kg,and 70.55% of the soil organic matter content in Jiaxian County was in the suitable range;The average alkali-hydrolyzed nitrogen content was 119.70mg/kg,and 76.03% of the alkali-hydrolyzed nitrogen content was more than 100mg/kg,the content was higher than the suitable range.The average soil available phosphorus content was 20.59mg/kg,and the content of soil available phosphorus in most towns was above 12mg/kg.The average content of soil available potassium was 180.59mg/kg,and the area with content ≥100mg/kg accounted for91.10%.The average content of soil water-soluble chlorine was 23.42mg/kg,and 76.71% of the samples contained were less than 30mg/kg chloride.The cluster analysis results of the comprehensive evaluation index of soil suitability in each township showed three types:Wangji,Yaozhuang,Likou,Tangjie and Baimiao township were the first type,their soil suitability was the best.Huangdao,Zhongtou,Changqiao,Ciba,Anliang and Zhayuan Town were in the second category,the comprehensive evaluation index of this category was relatively close,and the soil suitability was relatively suitable.Xuedian town was the third category,and its soil suitability index was the lowest.4.The chemical composition and coordination of tobacco leaves were evaluated.The nicotine content of B2 F and C3 F in Jiaxian County was relatively suitable as a whole,Nearly 50% of the samples of B2 F and C3 F had a suitable total sugar content;The reducing sugar content was moderate,72.31% of B2 F and 67.69% of C3 F samples were in the suitable range;The total nitrogen content was in the suitable range,the potassium content was generally low,and the chlorine content was generally high;Nearly 50% of the tobacco samples of B2 F and C3 F had a low two-sugar ratio,and more than 60% of B2 F and C3 F tobacco leaves were in the suitable range;the overall potassium-chloride ratio was low.The chemical composition of tobacco leaves in different towns showed different degrees of differences.The climate of Jiaxian Tobacco area is generally suitable to meet the production needs of high-quality tobacco leaves,but the rainfall is less in the early stage and more in the later stage,so it is necessary to strengthen the irrigation in the early stage and the waterlogging prevention in the later stage.It is suggested that tobacco planting regions should be preferentially concentrated in the most suitable and more suitable soil regions.In view of the problems of soil properties and tobacco leaf quality,comprehensive regulation should be carried out by optimizing nutrient fertilization cultivation and modulation techniques to improve tobacco leaf quality.