Purpose In order to know the curing characteristics of different tobacco cultivated varieties (strains) in Guizhou, some suggestions were put forward for improving the quality of flue-cured tobacco leaves.
Method Taking the middle leaves of K326, Bina 1, Jiucaiping 2, Hongda, Guiyan 2, Nanjiang 3 as materials, the difference of physiological indexes, color and yellowing degree during loose leaves bulk curing and economic characters and appearance quality of flue-cured tobacco leaves were studied.
Result The results showed that K326, Bina 1 and Guiyan 2 had a better coordination between yellowing and water loss rate, a high yellowing rate, an easier color fixation during 0-96 h of loose leaves curing and a better economic characters of flue-cured tobacco leaves. Then, Jiucaiping 2 and Nanjiang 3 had a medium yellowing rate and pigments degradation, a better performance of endurable curing potential during curing and a medium to higher economic characters of flue-cured tobacco leaves. However, Hongda had the lowest yellowing rate, a quicker water loss, a higher content of pigments and a lower rate of green color fading during curing. Thereby, Hongda had a poor appearance quality and economic characters of flue-cured tobacco leaves. The flue-curing characteristics of different flue-cured tobacco varieties (strains) were strongly related to the anti-oxidation and defense capability of POD and LOX. In addition, the chlorophyll enzyme and LOX were closely associated with the easy curing potential, while POD and PPO were closely related to the endurable curing potential of flue-cured tobacco leaves.
Conclusion According to the curing characteristics of different flue-cured tobacco varieties (strains), K326, Bina 1 and Guiyan 2 should moderate water loss and promote tobacco leaves yellowing based on synchronization between yellowing and reducing air humidity of bulk curing barn. Additionally, Jiucaiping 2 and Nanjiang 3 should turn yellow under relatively high moisture condition and prolong yellowing time of 10-15 h. Then all of them turn to normal leaf drying stage. As for Hongda, it should turn yellow under high moisture condition in the early stage of yellowing. Then it should properly decrease air humidity of bulk curing barn in the middle and later yellowing stage, and prolong yellowing time of 20-30 h based on leaf color change. In the leaf drying stage, it should keep leaf drying under relative higher moisture condition, promote the yellowing of tobacco leaves and the transformation of internal substances. These findings provide an important basis for flue-curing of different flue-cured tobacco varieties (strains).
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