Effect of Removing the Lower Leaves on the Physiological Features and Aroma Constituents of Flue-Cured Tobacco

Yunyan 97 was selected as the raw material. The effects of removing different number （0, 2, 3 and 4） of lower leaves on root activity, chlorophyll content, physiological features and contents of neutral aroma constituents in the flue-cured tobacco were analyzed. The results showed that the removal of lower leaves could significantly increase the root activity, chlorophyll content, net photosynthetic rate （Pn） and transpiration rate （Tr）, and delay the photosynthetic functional decline. Such effects were the greatest in lower leaves, followed by middle leaves and upper leaves. Moreover, the degree of the effects increased with higher number of leaves removed. After She lower leaves were removed, the water use efficiency （WUE） of leaves in the first 10 d became higher with more leaves removed. In the later periods （24 d, 38 d）, WUE decreased with more leaves removed. For the middle and upper leaves, the removal of three leaves （T2） and two leaves （T1） resulted in the highest contents of aroma constituents, respectively. For the tobaccos cultured in soil with moderate fertility under the experimental conditions, the appropriate number of lower leaves removed should be 2-3.

Study on Improving the Internal Quality of Tobacco Stems by Using Pectinase

[Objective] This study aimed to reduce the content of cell wall materials in tobacco stems and improve their internal quality. [Method] Pectinase was used to decompose cell wall materials in tobacco stems, followed by determination of the contents of four cell wall materials, six routine chemical components, as well as aroma constituents. [Result] Pectinase could effectively reduce the contents of cell wall materials in tobacco stems, with the largest decrease of 6.84%; after pectinase treatment,the content of reducing sugar in tobacco stems increased obviously, and the contents of total sugar, potassium ion, chloride ion and total nitrogen increased to varying degrees, of which the contents of potassium ion and reducing sugar displayed upward trends with the increase of pectinase concentration. Pectinase treatment significantly increased the contents of Maillard reaction products, with the most increase of 67.2%;the contents of carotenoid degradation products, phenylalanine degradation products and neophytadiene all increased to varying extents, and the contents of both Maillard reaction products and phenylalanine degradation products revealed ascending trends with the increase of pectinase concentration. [Conclusion] Pectinase treatment can effectively decompose cell wall materials in tobacco stems, improve routine chemical constituents, and increase the contents of aroma constituents.