贵州省烟草科学研究院

【Objective】Exploring the effects of frequency conversion regulation of intensive baking circulating fans on the dehydration and yellowing characteristics of tobacco leaves and their stress tolerance during the baking process, it will provid theoretical and practical support for optimizing the frequency conversion regulation of intensive baking circulating fans, and improving the quality and economic benefits of tobacco drying in actual production.【Method】Using the middle leaves of 'Yunyan 87' as the material, a comparative analysis was conducted on the water loss characteristics, color parameters, pigment content, antixidant enzyme activity, MDA content, physical properties, and chemical composition of tobacco leaves after baking under the fixed high-frequency group (CK, frequency 50 Hz) and the variable frequency control group (T, frequency 35 Hz-40 Hz-45 Hz-40 Hz).【Result】The frequency conversion control of the intensive baking fan prolonged the yellowing and color fixing periods of tobacco leaves, shortened the dry gluten period, and extended the total baking time by 8 hours. The variable frequency control group lost water slower in the middle and late stages of yellowing and color fixing, and the moisture content of tobacco leaves was significantly higher than that of the fixed high-frequency group after 60-96 hours of baking, which was beneficial for the degradation of total chlorophyll and carotenoids. After baking, the total chlorophyll and carotenoids of the variable frequency control group were significantly lower than that of the fixed high-frequency group, reduced by 58.03% and 73.79%, respectively. The variable frequency control group has a relatively high activity of antixidant enzymes during the color fixation period, which is beneficial for clearing ROS during the baking process. The MDA content significantly decreased at 48-96 hours, with a decrease of 29.18% to 53.35%. The overall color change of variable frequency control group was uniform and the color was relatively bright. Analysis of tobacco leaves after baking revealed the variable frequency control group increased leaf width and single leaf mass by 10.63% and 27.5%, respectively, while reducing softness value by 9.92% and improving softness. The variable frequency control treatment of the fan promoted the decomposition of large molecular substances such as starch and protein. After baking, the content of total nitrogen, potassium, starch, and protein in the leaves of the variable frequency control group decreased by 4.70%, 5.70%, 3.94%, and 8.65% respectively, compared to the fixed high-frequency group, and the total sugar content increased by 4.01%. The sensory evaluation quality test showed that the sensory evaluation quality of tobacco leaves in the variable frequency control group was significantly better than that in the fixed high-frequency group.【Conclusion】Compared to fixed high-frequency baking, variable frequency control of fans is more conducive to the coordination of yellowing and dehydration of tobacco leaves, which can improve the stress tolerance of tobacco leaves during baking, promote the transformation of internal substances and the improvement of physical properties of tobacco leaves after baking, and enhance the quality and sensory evaluation of tobacco leaves after baking.

The main cultivated soil types(yellow soil)in Guizhou Province was selected in this study.Soil samples were collected from fields that had been planted with tobacco and maize for a long time,and the content of organic carbon and the characteristics of clay minerals in the soil were determined.The study aimed to investigate the differences in the influence of clay mineral composition on organic carbon fixation under the cultivation of tobacco and maize.The results indicate that the organic carbon content in the soil for maize cultivation is higher than that in the soil for tobacco cultivation.The results of mineral analysis by XRD reveal that the compositions of clay minerals in the soils of the two crops are similar,both containing illite,kaolinite and vermiculite.Nevertheless,the content of illite in the corn cultivated soil is significantly higher than that in the tobacco cultivated soil,and the content of kaolinite in the tobacco cultivated soil is significantly higher than that in the corn cultivated soil.The main 2:1 type clay mineral in the corn cultivated soil is illite,while the main 1:1 type clay mineral in the tobacco cultivated soil is kaolinite.The content of illite is significantly positively correlated with the content of organic carbon(r=0.69,P＜0.05),while the content of kaolinite is significantly negatively correlated with the content of organic carbon(r=0.81,P＜0.05).Furthermore,the activity of Ribulose-1,5-diphosphate carboxylase/oxygenase(RubisCO)in the corn cultivated soil is significantly higher than that in the tobacco cultivated soil.In summary,corn cultivated soil is more favorable for the retention of organic carbon than tobacco cultivated soil.The composition of clay minerals and their relative contents exert a significant influence on the adsorption of organic carbon.

The stability of phyllosphere microbial community is closely related to plant health.In order to understand the microecological characteristics of tobacco leaves infected with wildfire disease,community structure and diversity of phyllosphere microbiome in diseased spots and healthy tissues of tobacco leaves with different degrees of disease were analyzed using high-throughput sequencing technology in this paper.The results were as follows:(1)The dominant microorganisms in diseased and healthy tissues were Proteobacteria and Ascomycota,and their relative abundance in diseased tissues was significantly higher than that in healthy tissues.The dominant genera were Pseudomonas,Pantoea,Alternaria,Plectosphaerella and Conocybe,and only the relative abundance of Pseudomonas in diseased tissues was significantly higher than that in healthy tissues.(2)The diversity and richness of bacterial communities in diseased spots were higher than those in healthy tissues,and the diversity index showed a trend of decreasing and then increasing with the increase of the disease degree,and the richness index showed a trend of increasing and then decreasing.The richness and diversity index of fungal communities in diseased spots showed a trend of increasing and then decreasing with the increase of the disease degree,and the diversity index and richness of fungal communities in diseased spot tissues of mildly and moderately diseased leaves were higher than those in healthy tissues,but the diversity index and richness of fungal communities in heavily diseased tissues were lower than those in healthy tissues.(3)Gene functional information and relative abundance of bacteria in diseased spots and healthy tissues were generally similar,primarily were metabolism,genetic information processing and environmental information processing.The dominant functional taxa of fungus were plant pathogen,animal pathogen-endophyte-plant pathogen-wood saprotroph,undefined saprotroph,wood saprotroph and plant pathogen-wood saprotroph.The results provide a reference for the understanding of evolutionary pattern of tobacco wildfire disease and characterization of the phyllosphere microbial community.

α-Cembrenediol displays a diverse array of biological activities,encompassing antibacterial,antitumor,and neuroprotective effects.To comprehensively understand the in vivo transport,distribution,and elimination mechanisms associated with α-cembrenediol,its interaction with bovine serum albumin(BSA)was investigated.In this study,the interaction between α-cembrenediol and BSA was explored using various techniques,including UV absorption,steady-state fluorescence,circular dichroism spectrum,molecular docking,and molecular dynamics simulation.The results showed that there was a clear interaction between BSA and α-cembrenediol.Specifically,the KSV and Kb decreased with increasing temperature at 293,303,and 310 K,indicating that α-cembrenediol interacted with BSA through a static quenching mechanism.Furthermore,the number of binding sites was approximately 1 at the three temperatures,suggesting the presence of a single specific binding site for α-cembrenediol on BSA.Moreover,the binding process occurred spontaneously(ΔG＜0),primarily driven by hydrogen bonds and van der Waals forces(ΔH＜0 and ΔS＜0).α-Cembrenediol bound to the Sudlow site Ⅰ of BSA.Binding of BSA to α-cembrenediol also caused its conformation to change.This study provides essential insights into the interaction between α-cembrenediol and BSA,contributing to a better understanding of the pharmacokinetic properties of the compound.