| Flue-cured tobacco,as a foliar economic crop with importance both of yield and quality,is very sensitive to environmental conditions.Ecological factors such as climate,soil,topography and geology have an important impact on the growth,quality and flavor formation of tobacco leaves.Wuxi County,Chongqing City belongs to the tobacco planting area in the Qinling-Daba tobacco area.The topography of the study area is complex,and the three-dimensional climate of the mountain tobacco area is obvious.The spatial data of ecological factors such as climate,soil,topography and geology has not been fully constructed in the study area.There is great complexity and uncertainty in the management of flue-cured tobacco cultivation.Therefore,it is of great significance to understand the characteristics of the eco-environment and explore the potential of the eco-environment suitability of high-quality tobacco leaves to improve the pertinence of flue-cured tobacco planting management in a large-scale range and to promote high-quality and suitable crop yields.Taking Wuxi County,Chongqing City,a typical area of Qinling-Daba tobacco area as the research object.Geostatistics and spatial analysis methods were used to construct a spatial dataset of ecological factors.Geostatistics and spatial analysis methods were used to construct a spatial dataset of ecological factors.The ecological suitability evaluation index of high-quality tobacco leaves was screened by analyzing the relationship between the sensory evaluation quality and ecological factors.The ecological suitability index（SI）was calculated by combining the weights determined by the analytic hierarchy process and the entropy weight method with the membership degree determined by the fuzzy comprehensive evaluation,and the SI of each grid was used to further evaluate and delineate high-quality tobacco leaf production areas.Then,combined with the sensory evaluation and chemical composition of the verified tobacco leaf samples,the results of the regional division of ecological suitability of high-quality tobacco leaves were preliminarily verified.The main results are as follows:（1）The ANUSPLIN interpolation method was the best spatial prediction method in the spatial interpolation of rainfall,temperature and sunshine hours,the IDW interpolation method was the best spatial prediction method in the relative humidity spatial interpolation,and the OK interpolation methodwas the best spatial prediction method in soil factors.Based on the above spatial data extraction methods,the ecological characteristics of study area were analyzed.In Wuxi County,Chongqing City,the precipitation of each flue-cured tobacco growing season were 161.62,218.63 and 461.72mm,the average temperature were 17.45,20.62 and 21.88℃,the sunshine hours were162.98,129.26 and 467.67 h,the average relative humidity were 73.21%,77.03%and75.31%,respectively.The average soil p H was 6.56,and the average contents of soil SOM,TN,AN,AP and AK were 23.35 g·kg-1,1.30 g·kg-1,110.12 mg·kg-1,20.88 mg·kg-1 and240.26 mg·kg-1,respectively.The lowest elevation is 209 m and the highest elevation is2494 m.The terrain is dominated by mountains,with steep slopes and obvious three-dimensional landforms.There were 22 types of geological rock formations,of which the Triassic Jialingjiang Formation dolomite,breccia and limestone accounts for the largest proportion（47.23%）.（2）Based on the sensory evaluation of tobacco leaf samples in 2019,the relative comprehensive scores of tobacco leaves were calculated by principal component analysis method and relative score method,and the tobacco leaf samples were divided into high-quality group and control group（the relative comprehensive score equal or greater than97.5 was classified as high-quality tobacco leaves）.The ecological characteristics of tobacco leaf samples in different groups were analyzed,and there were significant differences in ecological factors such as average temperature,sunshine hours,soil p H and altitude（P<0.05）.After independent sample t-test and bivariate correlation analysis,the important ecological factors with significant differences between different groups and significantly correlated with high-quality tobacco leaves were determined（21 factors）,and included in the comprehensive evaluation of ecological suitability of high-quality tobacco leaves.The ecological suitability index（SI）was classified into 4 grades（SI value≥0.85 is the highly suitable,0.65～0.85 is suitable,0.45～0.65 is moderately suitable,<0.45 is not suitable）,and the comprehensive evaluation of ecological suitability of high-quality tobacco leaf was obtained.The results showed that the highly suitable,suitable,moderately suitable and not suitable areas were respectively accounted for 31.93%,21.34%,23.80%and 22.93%of the total area of the study area.（3）In 2020,10 tobacco leaf samples were taken to evaluate sensory evaluation and chemical composition indicators were evaluated.According to the relative comprehensive scores of tobacco leaf samples,all samples were divided into two groups:high-quality group and control group according to the same evaluation standard.Among them,high-quality tobacco leaves scored for aroma amount（6.17 points）,irritation（6.21points）and sweetness（6.24 points）were significantly higher than the control tobacco leaves（P<0.05）,and the coincidence rate between the quality of tobacco leaf samples and the distribution of ecological suitability reached 80%.Each tobacco leaf sample was within the appropriate range of chemical composition of high-quality tobacco leaves in Qinling-Daba Mountain Area,and the content of total sugar,reducing sugar and nicotine and the comprehensive index of chemical components in high-quality tobacco leaves were significantly lower than those in control tobacco leaves（P<0.05）.The results showed that there were significant differences in the content of total sugar,reducing sugar and nicotine between the most suitable area and the ecologically suitable area of high-quality tobacco leaves,and the above chemical components were all low within the suitable range.To sum up,this paper constructed a high-precision ecological factor spatial data set and combined tobacco leaf samples to classify and verify the ecological suitability of high-quality tobacco leaves,which provided an effective way to excavate suitable areas for high-quality tobacco leaves.The climate,soil,topography and geology have important influences on the suitability of high-quality tobacco leaves.The highly suitable areas were distributed in all tobacco-growing towns.In addition to the high quality of sensory evaluation of high-quality tobacco leaves,total sugar,reducing sugar and nicotine contents were low in the appropriate range.The results of this study provided a decision-making reference for making use of ecological resources in Qinling-Daba tobacco area according to local conditions,optimizing the planting layout of flue-cured tobacco,and promoting high-quality and suitable yield of flue-cured tobacco. |
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