Effects of Exogenous Spraying of Methyl Jasmonate on Maturation and Cured Quality of Late-maturing Upper Tobacco Leaves

WANG Tingting; ZHAO Yuanyuan; XIA Yulan; WANG Dexun; LI Juan; SUN Junwei; SHI Hongzhi

doi:10.15933/j.cnki.1004-3268.2025.05.006

Abstract：To investigate the effects of exogenous methyl jasmonate(MeJA)application on maturation and quality improvement in delayed-maturity upper leaves of flue-cured tobacco,a field experiment was conducted using the Yunyan 300 cultivar.Four MeJA concentrations(1,5,10,15 mmol/L)were foliar-applied for three consecutive days during the late growth stage of upper leaves.Morphological changes in the tobacco leaves were recorded,and the SPAD values of fresh leaves were measured.Additionally,the contents of conventional chemical components(starch,protein,nicotine,and water-soluble sugars)in fresh leaves were determined.After curing,the contents of conventional chemical components,physical properties,appearance quality,sensory quality,and neutral aroma components of the cured leaves were also determined and evaluated.The results showed that the leaves treated with 10 mmol/L and 15 mmol/L MeJA solution exhibited significant chlorophyll degradation and yellowing after 24 hours of the final application,with SPAD values decreasing by 13.75％and 15.33％,respectively.Compared to the control group(0 mmol/L MeJA solution,CK),exogenous applications of 5,10,15 mmol/L MeJA solution significantly reduced the contents of starch,soluble protein,reducing sugar,and total sugar in fresh leaves,while nicotine content increased significantly.Among these treatments,the 10 mmol/L MeJA solution resulted in the highest nicotine content,which increased by 48.34％compared to CK.After curing,the reducing sugar and total sugar contents in leaves treated with 10 mmol/L MeJA increased by 47.37％and 13.06％,respectively,compared to CK,indicating a more balanced chemical composition.Exogenous applications of different concentrations of MeJA solution also improved the sensory and aromatic quality of cured leaves,with an increase in neutral aromatic compounds.Notably,the content of solanone increased the most,with a 90.90％increase in leaves treated with 10 mmol/L MeJA compared to CK.In summary,exogenous MeJA solution can effectively promote the maturation and yellowing of flue-cured tobacco,as well as enhance its quality.Continuous foliar applications of 10 mmol/L MeJA solution for three days result in significant chlorosis and yellowing in fresh leaves,with the quality of cured leaves being significantly enhanced.