Relationship Between Pigment Concentration and Color Attributive Parameters of Tobacco Leaves During Flue-curing

In order to find out the relationship between color attribute and pigment concentration of tobacco leaves, their variation and relationship during flue-curing were studied by taking tobacco leaves of different maturities of cv. Honghuadajinyuan as objects. The results showed that in the whole process of flue-curing, the R4B values of leaf was R (the brightness value of red in color digital image) > G (the brightness value of green in color digital image) > B (the brightness value of blue in color digital image). The samples of different maturities in the order of R, G and B mean values were overripe leaves > ripe leaves > unripe leaves. Chlorophyll degraded faster in leaves of lower maturities than in leaves of higher maturities. The content of carotenoid in unripe leaves decreased sharply at yellowing and color-fixing stages, and closed to that in ripe and overripe leaves at the end of color-fixing stage; however, less carotenoid was degraded in overripe leaves. The R value was extremely significantly negatively correlative to chlorophyll content, and B value significantly correlated to carotenoid content. The combination of R and G, r and g (hue component) had a good correlation with pigment concentration. There was a significantly positive relationship between H (tone) value and the contents of chlorophyll and carotenoid. Eight parameters significantly correlated to pigment concentration of tobacco leaf, including H, g, r-g, G-R, G/R, G/(R +B), (G-R)/(G +R) and (R-G)/(R +G +B), were selected to establish the stepwise regression equations for pigment concentration, which reached a significant level by F-test. Therefore, the correlation between color attribute and pigment concentration of tobacco leaves of different maturities was significant during flue-curing, and it could be used as an auxiliary means to judge the pigment concentration of flue-cured tobacco leaves.