Figure 4.

Differences in pigment content (a), carotene content (b), chlorophyll a (c), chlorophyll b (d) in flue-cured tobacco and burley tobacco at the same nitrogen level and same leaf biomass accumulation condition. NL_G1: low nitrogen level, HD; NL_G2: low nitrogen level, Z100; NL_Y1: low nitrogen level, TN90; NL_Y2: low nitrogen level, TN86; NH_Y1: high nitrogen level, TN90; NH_Y2: high nitrogen level, TN86. Error bars indicate standard error of the means (n = 3). Symbols ** ¹ indicate that the significant differences between flue-cured tobacco and burley tobacco at the same nitrogen application are at 0.01, respectively. Symbols ** ² indicate that the significant differences between flue-cured tobacco and burley tobacco at the same leaf biomass accumulation condition are at 0.01, respectively.