Effect Of Ecological Factors On The Economic Characters Of Flue-cured Tobacco In Chongqing Based On CART

As a kind of economic crop,flue-cured tobacco(FCT)is very sensitive to the growing environment.The ecological condition is the basic of FCT growth and flavor and quality.Chongqing tobacco-growing area is one of the most suitable production area for high-quality tobacco in China.However,the geographical environment of Chongqing is quite complicated,and the ecological factors are very different,which makes a great regional difference of FCT in Chongqing.It is very important to clarify the influence of ecological factors on the quality of FCT.However,due to the lack of spatial distribution of tobacco-growing counties and dry land that has the possibility of tobacco-growing,it is difficult to match the ecological data and specific planting points,increasing the difficulty of research.In addition,there is a lack of work on the climatic conditions classified by the growth periods of FCT according to the different demands of FCT for light,temperature and precipitation at different growth stages in related systematic studies.Regarding the issue above,the regional characteristics of ecological environment in Chongqing tobacco-growing areas were systematically analyzed by investigation,geostatistics,correlation analysis,fuzzy c-means clustering,single factor ANOVA test and CART in this paper.The climatic factors were classified according to the growth period of FCT,and the relationships between the ecological factors and the economic characters of FCT were further clarified.Based on the calculation results of CART,the relative importances of the effects of the ecological factors on the economic characters of FCT in Chongqing were sorted,so as to select the limiting factor of FCT growth.The results provide references for cultivating management and production technology with local ecological conditions,which was helpful to improve the rational allocation of FCT resources in Chongqing.The main results are as follows.1.The special database of climatic factors,geological strata,geology and geomorphology,soil nutrients and the economic characters of FCT in Chongqing tobacco-growing areas was constructed,and their regional characteristics were clarified.Then the ecological factors significantly correlated with the economic characters of FCT were screened.The average values of monthly sunshine hours,monthly mean temperature and monthly mean precipitation were122.5 h,19.0? and 150.1 mm,respectively.The sunshine hours of northeast of Chongqing were higher than that in southeast.The monthly mean temperature in southeast and a few northeast were higher than that in the middle of Chongqing.The precipitation in Nanchuan,Wulong and Pengshui were lower than that in Qianjiang and Youyang,the precipitation of seedling rooting period was lower but that in mature period was higher in Wuxi.In the dry land of 600-1400 m in Chongqing tobacco-growing village,there were 30 types of geological strata,the area of Daye group limestone dolomite was the largest,accounting for 45.22% of the total area,Liangshan formation of Permian Wujiaping limestone and dolomite secondly,the mean values of altitude,slope and curvature of the profile was 1010 m,17°and 5.21°,the proportion of the semi-sunny slopes and the semi-shady slopes in the southeastern Chongqing area was larger,the distribution of shady slope and sunny slope in the northeastern Chongqing was more concentrated.There were great spatial differences of the soil nutrients.The sunshine hours and mean temperature of each period,the precipitation of mature period and field period,altitude,soil p H,total phosphorus and available S,Fe,Cu and Mn were very significantly or significantly correlated with the FCT yield.The mean sunshine hours of each period,the mean temperature of mature period,the precipitation of mature period and field period,altitude,aspect,soil p H,exchange Mg and available S,Cl,Zn and Mn were very significantly or significantly correlated with proportion of middle and first-class tobacco of FCT.2.The yield and the proportion of middle and first-class tobacco of FCT were classified,respectively.The relative importances of the ecological factors on the classification were discussed to clarify the limiting factors of improving the economic characters of FCT.The results of fuzzy c-means clustering method show that when the yield and the proportion of middle and first-class tobacco of FCT was respectively divided into three classes,the classification performed best.The group with high yield had the characteristics of more sunshine hours at vigorous period and precipitation at field period,lower average temperature at mature period,higher altitude,and the soil index of higher p H,TP and available S,and lower available Mn content.The group with high proportion of middle and first-class tobacco had the characteristics of more sunshine hours at vigorous period and precipitation at mature period,lower average temperature at mature period,higher altitude,more semi-sunny and sunny slopes,and higher soil p H and exchange Mg,lower available Mn.And the proportions of limestone dolomite in geological strata of high yield or high proportion of middle and first-class tobacco of FCT were both above 70%.The results of CART showed that the relative importance of each factor to the yield of FCT was as follows: sunshine at vigorous period > mean temperature at mature period > available Mn > p H > altitude > precipitation at field period > available S > TP > geological background > available Zn > available Cu > available Fe.The relative importance of the factors on the proportion of middle and first-class tobacco of FCT was as follows: sunshine at vigorous period > precipitation at mature period > geological background > available Mn > mean temperature at mature period > altitude > p H > aspect > exchange Mg > precipitation at seeding and rooting period > Cl > available S > available Zn.3.The ecological factors significantly correlated with the FCT economic characters had different significant differences among the 9 economic trait classes of FCT.The relative importance of the ecological factors on the FCT production(or proportion of middle and first-class tobacco)in different tobacco-growing area of different proportion of middle and first-class tobacco(or production)was clarified.The proportions of the economic characters with high yield–high quality,middle yield-high quality and middle yield-middle quality were higher,the sample with high yield –high quality accounted for only 1.64% of the total sample.In space,the level of economic characters in Wushan was highest with the proportion of high yield-high quality sample accounted for 96.83%.The fewer classes of FCT the tobacco-growing county included,the more concentrated and stable the level of flue-cured tobacco was.On the contrary,it showed that the quality of FCT production in this region is quite different,and different measures could be taken to manage the tobacco fields.In economic trait with high yield,the effect of climatic conditions and soil nutrients on the proportion of middle and first-class tobacco was greater than terrain factors and geological background.In economic trait with medium yield,the effect of climatic conditions on the proportion of middle and first-class tobacco was greatest,and that of terrain factors and geological background were greater than soil nutrients.In economic trait with low yield,the effect of climatic conditions,soil nutrients and terrain factors on the proportion of middle and first-class tobacco had no significant difference.In economic characters with high or medium proportion of middle and first-class tobacco,climatic conditions and geological background were the main reasons for FCT yield classification.In economic characters with low proportion of middle and first-class tobacco,Soil nutrients were the main reasons for FCT yield classification,and the geological background contributed the least.In this paper,by analyzing the relationship between the ecological factors and the economic characters of FCT,it was found that the sunshine hours,precipitation,altitude and soil available manganese content had a great effect on the FCT growth.The characteristics of different ecological factors in the grades with different yield,proportion of middle and first-class tobacco and the combination of the two were analyzed.of the effects of climate,geological strata,geology and geomorphology,and soil nutrients on the economic characters of FCT production were clarified.The factors leading to the difference of economic characters of FCT and their spatial distributions were screened,which provided important references for the optimization of the production layout of high-quality tobacco in Chongqing.