烤烟生育期间主要非挥发性有机酸含量及相关酶活性变化特征

Main Non-volatile Organic Acid Concentrations and the Relative Enzymatic Activity Changes during the Growth Periods of Flue-cured Tobacco

以12个烤烟品种为材料,通过测定烤烟中部叶有机酸总量、苹果酸含量、柠檬酸含量、代谢相关酶活性的动态变化以及烤后烟碱含量和感官质量,探讨烤烟生长过程中叶片主要非挥发性有机酸含量及代谢相关酶活性变化规律.结果表明：（1）随着烟株的生长发育,烤烟中部叶有机酸总量呈先升高后降低趋势,于叶龄50～60 d时达到最高值；烤烟品种间中部叶有机酸总量在各叶龄时期存在极显著差异,而在调制前后变化不大.（2）苹果酸含量呈“逐渐升高”趋势；柠檬酸含量呈缓慢“增-减”的趋势；苹果酸含量与苹果酸脱氢酶（NAD-MDH）活性之间极显著负相关；柠檬酸含量与柠檬酸合成酶（CS）活性之间极显著正相关,而与异柠檬酸脱氢酶（NAD-IDH）活性相关性不大.（3）当有机酸总量大于32％,同时烟碱含量介于1.5％～2.6％时,“酸碱比”较高的烟叶感官质量较好.研究认为,烤烟叶片苹果酸和柠檬酸的积累受其代谢相关酶活性变化的调控,“酸碱比”影响烤烟烟气的醇和度,可通过调控NAD-MDH和CS活性来调节苹果酸和柠檬酸的含量,协调“酸碱比”,提高烟叶质量.

In order to clarify the changes of main non-volatile organic acid concentrations and metabolism re- lated enzymatic activities in the process of the growth of flue-cured tobacco leaves,we used 12 flue-cured tobacco varieties to study the dynamic changes of total organic acid content,malic acid content, citric acid content, metabolism related enzymatic activities, the nicotine content and sensory quality of modulated smoke sample. The results showed that ： （1） With the growth of tobacco plants, flue-cured tobacco total or- ganic acid content indicated a trend of first increased and then decreased,in the middle of leaf age 50~60 d reached the highest value. The total organic acid content of different flue-cured tobacco variety middle leav- es had significant differences in different age periods, while had little changes before and after modulation. （2）Malic acid content had a trend of gradually growth. Citric acid content displayed a slow ＂increase-de- crease＂ trend. Malic acid content and the NAD-MDH（malic dehydrogenase） activity had a significant nega- tive correlation. Citric acid content and the CS（citrate synthase） activity had a significant DOsitive correla tion, while had little correlation with the NAD-IDH （isocitrate dehydrogenase） activity. （3） When the total organic acid content was more than 32~ ,nicotine content was between 1.5% and 2.6% at the same time, the higher ＂acid-base ratio＂,the better sensory quality of flue-cured tobacco. In summary,the accumulation of malic acid and citric acid in flue-cured tobacco leaf were regulated by the changes of its metabolism relat- ed enzymatic activities. ＂Acid-base ratio＂ influenced the smoke mildness of flue-cured tobacco. Through regulating NAD-MDH and CS activities to adjust the contents of malic acid and citric acid, coordinating ＂acid-base ratio＂ and improving the quality of tobacco.