Comprehensive Evaluation of Main Physical Indices of Flue-cured Tobacco Based on Principal Component and Cluster Analysis

107 of flue-cured tobacco from 13 tobacco-growing counties were selected to analyze in order to evaluate the physical quality of flue-cured tobacco more accurately in Hubei province. Five physical indices, including leaf tension stress, tensile strength, breaking elongation, leaf weight and thickness, were analyzed by descriptive statistics and correlation analysis, and principal component analysis was employed to build a composite score mathematical model, then the composite score was further analyzed by hierarchical cluster. The results showed that different positions of physical indices presented different otherness, and the physical indices had significant or highly significant positive correlation among each other, in addition to the breaking elongation and thickness. The 107 of samples were assembled into 5 classes according to their composite scores, whose quality and score were as follows: the best, 0.99~1.62; second to the best, 0.30~0.80; moderate, -0.11~0.24; poor, -0.89~-0.21; and very poor, -1.09~-0.97. The results had significance on the assessment of physical quality of flue-cured tobacco and industrial application of tobacco materials.