Classification of cigar tobacco leaf planting areas in Hunan based on climatic conditions

【Objective】To clarify the climatic similarity between cigar tobacco leaf planting areas in Hunan and foreign high-quality cigar tobacco leaf planting areas, so as to provide reference for climate evaluation on different cigar tobacco planting areas in Hunan and select suitable cigar tobacco leaf types.【Method】Eight cigar tobacco leaf planting areas in Hunan(Ningxiang of Changsha, Changning of Hengyang, Shuangpai of Yongzhou, Yongding of Zhangjiajie, Cili of Zhangjiajie, Sangzhi of Zhangjiajie, Guidong of Chenzhou and Mayang of Huaihua) were selected. The monthly temperature, rainfall, relativehumidity, short-wave radiation net intensity and sunshine hours from the first month to the fifth month after transplanting were usedas climatic factors, and the climatic similarity among the planting areas and foreign high-quality cigar tobacco leaf planting areas(wrapper planting area in Saint Luis, Cuba;fillerplanting area in San Juan Martínez, Cuba;Non-Cuba wrapper planting area Ecuador;Non-Cuba filler planting area Dominica) was analyzed.Cluster analysis and orthogonal partial least squares discriminant analysis(OPLS-DA) were combined for classification of the planting areas and further explication of their differences in climatic conditions.【Result】The results showed that the climatic conditions of the eight cigar tobacco leaf planting areas in Hunan were moderately similar to those in Cuba wrapper planting area, and the climatic conditions of Ningxiang of Changsha, Sangzhi of Zhangjiajie and Guidong of Chenzhou were also moderately similar to those in Non-Cuba filler planting area Dominica. Based on climatic conditions, the above areas could be divided into two classes. Class I was the areas that had the potential to produce cigar wrapper, with five areas included Cili of Zhangjiajie, Yongding of Zhangjiajie, Mayang of Huaihua, Changning of Hengyang and Shuangpai of Yongzhou, while class II was the areas that had the potential to produce both cigar wrapper and cigar filler, including Ningxiang of Changsha, Sangzhi of Zhangjiajie and Guidong of Chenzhou. The OPLS-DA model could successfully distinguish between class I and class II areas, indicating that climatic conditions of the two classes of areas were greatly different. The analysis results of variable importance in projection(VIP) predicting value showed that seven climatic indexes including short-wave radiation net intensity in the first, second, third and fifth months and sunshine hours in the first, second and third months after transplanting were the difference indexes between the two classes of areas(VIP>1.2). The higher short-wave radiation net intensity and sunshine hours of the class II areas were the main reasons for the production of cigar filler.【Conclusion】Cigar tobacco leaf planting areas in Hunan can be divided into wrapper production potential area and wrapper & filler production potential area. The most influential climatic factors of this classification are short-wave radiation net intensity and sunshine hours.