Effect of Integration of Stem Retention and Post-Ripening Technology on Roasting Quality of Upper Leaves
Li Chang
Zhan Jiawei
Guo Shiping
Feng Changchun
Wu Deyang
Qin Yanqing
Yang Xingyou
Song Chaopeng
Xie Liangwen
Jia Hongfang
Abstract：To clarify the effects of stem retention and post-harvest curing technology integration on curing quality of upper tobacco leaves,improve the proportion of medium-high grade tobacco,and establish theoreti-cal foundations and technical supports for further enhancing the curing quality of upper leaves,the upper Yun-yan 87 leaves were investigated in this study subjected to three treatments including conventional harvesting and curing(CK),conventional harvesting+24-hour post-harvest curing(ZC24),and 6-leaf stem-retention harvesting+24-hour post-harvest curing(DJ24).Scanning electron microscopy(SEM),transmission elec-tron microscopy(TEM),and real-time fluorescence quantitative analysis of gene expression were employed to elucidate the impacts of stem retention and post-harvest curing integration on curing quality at cellular biologi-cal and molecular levels.The results demonstrated that the leaf browning proportion followed the order of DJ24＜ZC24＜CK,with DJ24 showing 23.17％reduction of mild browning tobacco leaves compared to CK,indica-ting suppressed browning reactions.Post-curing grade analysis revealed that ZC24 and DJ24 treatments in-creased premium-grade tobacco proportion by 25.69％and 38.65％respectively compared to CK,while DJ24 achieved 8.52％overall improvement in medium-high grade proportion.Stem-retained and post-harvest cured leaves exhibited looser tissue structure and enhanced starch granule degradation,with DJ24 showing 35.78％reduction in starch content,49.04％and 14.82％increase in reducing sugars and total sugars compared to CK,indicating effective promotion of macromolecule degradation and chemical component coordination.Com-pared with CK,DJ24 demonstrated very significant reductions in contents of total fatty acids(P＜0.01),pal-mitic acid,stearic acid and arachidic acid,along with significant decreases in oleic acid,linolenic acid and linoleic acid(P＜0.05).Expression analysis of genes related with sugar and fatty acid metabolisms revealed downregulation of sucrose synthase(SS),invertase(INV),AGPase(AGP),lipid transfer protein 1(LTP1),MYB106 and CER10 genes in ZC24 and DJ24 treatments with more pronounced suppression in DJ24,which suggested that the integrated technology with stem retention and post-harvest curing effectively in-hibited the sugar and lipid metabolism during curing,improving chemical composition and leaf coloration.In conclusion,the 6-leaf stem-retention+24-hour post-harvest curing protocol could effectively suppress the ex-pression of sugar and lipid metabolism-related genes,mitigate leaf browning,enhance intrinsic chemical quali-ty,and reduce defective cured leaf proportion.
Keywords：Flue-cured tobaccoSix-leaf with stem and post-harvest processing integrationUpper leav-esSugar metabolismFatty acid metabolismBrowning
Publication Date：2025-10-30
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：8( 50-57 )