TABLE 2.
Changes of SPAD and chloroplast pigments in different curing stages with different salicylic acid concentrations.
| Treatment | Sampling temperature (°C) | Continuous curing time (h) | SPAD | Chlorophyll a (μg/g) | Chlorophyll b (μg/g) | Lutein (μg/g) | β-Carotene (μg/g) |
| Control | Fresh tobacco leaves | – | 35.6Aa | 154.04Ba | 78.27Ba | 137.73Aa | 2,089.93Aa |
| 38 | 23.5 | 8.7Abc | 24.9Ab | 13.21Ab | 129.38Aa | 2,046.98Ba | |
| 42 | 16.5 | 5.8Ac | 16.41Bb | 10.54Ab | 142.05Ba | 2,170.23Ba | |
| 48 | 15 | 6.2Ac | 9.81Ab | 4.45Ab | 127.61Aa | 2,351.72Aa | |
| 54 | 22.5 | 12.9Ab | 11.5Ab | 7.06Ab | 128.42Aa | 2,173.94Aa | |
| Initially flue-cured tobacco leaves | – | 11.32Ab | 7.77Ab | 136.5Aa | 2,350.62Ba | ||
| SA-1 | Fresh tobacco leaves | – | 40.8Aa | 238.05Aa | 142.1Aa | 170.07Ab | 2,116.48Ac |
| 38 | 23.5 | 6.6Ab | 28.79Abc | 16.4Ab | 186.32Ab | 2,357.03ABbc | |
| 42 | 16.5 | 5.5Ab | 111.49Ab | 56.93Ab | 291.5Aa | 4,048.59Aa | |
| 48 | 15 | 5.9Ab | 7.46Ac | 4.32Ab | 146.93Ab | 2,648.99Abc | |
| 54 | 22.5 | 4.5Bb | 3.27Ac | 2.83Ab | 197.09Ab | 3,077.14Aabc | |
| Initially flue-cured tobacco leaves | – | 12.08Ac | 7.45Ab | 199.85Ab | 3,386.15ABab | ||
| SA-2 | Fresh tobacco leaves | – | 40.2Aa | 232.35ABa | 161.56Aa | 196.78Aa | 2,544.12Aab |
| 38 | 23.5 | 10.9Ab | 57.55Ab | 22.84Ab | 197.26Aa | 3,265.91Aab | |
| 42 | 16.5 | 5.9Ab | 12.28Bb | 6.36Ab | 142.36Ba | 2,664.09Bab | |
| 48 | 15 | 10.8Ab | 6.35Ab | 2.88Ab | 141.25Aa | 2,531.51Aab | |
| 54 | 22.5 | 8.8ABb | 4.85Ab | 4.14Ab | 149.45Aa | 2,193.89Ab | |
| Initially flue-cured tobacco leaves | – | 8.8Ab | 5.63Ab | 209.69Aa | 3,559.81Aa |
Different capital letters indicate significant differences between treatments at the same stage (P < 0.05). Different lowercase letters indicate significant differences between the same treatments at different curing stages. Values represent the averages of three biological replicates.