| In this study,the meteorological data of Yibin tobacco growing area in recent ten years were monitored and sorted out by meteorological station.A large number of precise corresponding samples of soil and tobacco were collected.Cluster analysis and factor analysis were used to evaluate the ecological adaptability of Yibin tobacco growing area in combination with the specific changes of ecological factors in vertical space.The suitable areas for Yibin tobacco growing were further refined and excavated.The ecological basis and influencing factors of each region were studied.The effects of different ecological conditions on carotenoid degradation products in tobacco leaves were explored,and the key ecological influencing factors were identified.The aim is to find out the ecological characteristics of Yibin city,to make suggestions for the rational division of planting areas and the scientific management of flue-cured tobacco production,and to provide theoretical basis for regulating the content of carotenoid degradation products in tobacco leaves and improving the quality of tobacco leaves.The main research results show that:1.The climate conditions in Yibin tobacco-growing area are characterized by obvious synchronization of light,temperature and water,and high average temperature in mature period.The trend of climate change in different tobacco counties during the field period is the same as a whole,but the rainfall and sunshine time in different months are quite different among tobacco-growing counties,and the climatic conditions in Yibin tobacco-growing area have prominent regional characteristics,which can be divided into three regions:Area Ⅰ:Gaoping,Shangluo,Wangjia,with abundant rainfall,moderate temperature and sunshine hours;Area Ⅱ:Zhongdu,Jinping,Daba,with high temperature,suitable rainfall and sunshine hours.Zone Ⅲ:Artemisia sinensis and Xianfeng,with high sunshine hours,relatively low average temperature and rainfall,and the climatic conditions in Zone Ⅰ and Zone Ⅲ can better meet the needs of high-quality tobacco production for ecological conditions.2.Yibin tobacco-growing soils have abundant organic matter and total potassium,insufficient total phosphorus and chloride ions,and uneven distribution of nitrogen content.The characteristics of tobacco-growing soils in different tobacco-growing counties are relatively different,and the abundance and coordination of soil nutrients are better in Junlian County,followed by Xingwen County,and the deficiencies of nitrogen and phosphorus in Pingshan and Gongxian County.Among them,pH and organic matter are the important factors affecting the soil fertility performance of Yibin tobacco planting.Excessive Na content in soil is the limiting factor to reduce nutrient content.The tobacco-growing soils in Yibin are divided into three regions:Gaoping,Haoba,Daba,Shangluo and Wangjia,Zhongdu and Jinping,and Xianfeng.Among them,the third area has the best soil fertility performance,which has the advantages of abundant soil organic matter,alkali-hydrolyzed nitrogen,available phosphorus and available potassium,and the chloride ion content is also higher than other areas;the first area has the second comprehensive performance,and all soil fertility indicators are within the appropriate range,and the content of Al,Cu and Fe in mineral elements is rich.The organic matter,alkali-hydrolyzed nitrogen,total phosphorus and available phosphorus content in Area Ⅱ were significantly lower than those in other areas,while Na content was significantly higher than those in other areas.Pay attention to the regulation of soil acidity and alkalinity,give full play to the rich content of organic matter in Yibin tobacco-growing soil,"carbon conservation,nitrogen control,phosphorus extraction" is the focus of soil nutrient management in the future.3.The climatic and soil characteristics of Yibin tobacco-growing area in vertical space showed a significant trend of decreasing average temperature and increasing sunshine hours with the increase of altitude,while the rainfall was more abundant in the planting area at medium altitude.With the increase of altitude,the comprehensive performance of tobacco-growing soils increased significantly.The positive correlation between organic matter,total nitrogen,alkali-hydrolyzed nitrogen,total phosphorus,available potassium and altitude reached a significant level or above,and the low level of available phosphorus and chloride ions also improved in the middle and high altitude areas.When the altitude exceeds 900 m,the damage of high temperature to tobacco leaf growth and development can be reduced,and the rainfall is relatively moderate and the sunshine is abundant,and the comprehensive performance of soil is obviously improved,which is suitable for the high-quality production of tobacco leaf.4.With the increase of altitude,the content of carotenoid degradation products in Yibin production area increased gradually.Total phosphorus,available potassium,Fe and Mn in tobacco-growing soils were the key factors affecting the content of carotenoid degradation products in tobacco leaves,while Na and Zn were the main limiting factors.Mean temperature and sunshine hours in meteorological factors are the key factors affecting the content of carotenoid degradation products in tobacco leaves.With the increase of sunshine hours and rainfall in early growth stage,the increase of sunshine hours in vigorous and long-term,and the decrease of average temperature and sunshine hours in mature stage,the accumulation of carotenoid degradation products in tobacco leaves can be promoted to a certain extent. |
