采收时间对烤烟碳氮代谢关键酶活性和烟叶化学成分的影响

Influence of Harvesting Time on Key Enzyme Activities to Carbon and Nitrogen Metabolism and Main Chemical Components in Flue-cured Tobacco

为明确广东烟区烟叶充分成熟的外观特征,采用田间试验探讨了采收时间对烤烟碳氮代谢关键酶及烟叶主要化学成分的影响。结果表明:除腰叶之外,其他各部位烟叶淀粉酶活性均随着采收时间的推迟而逐渐升高,硝酸还原酶活性则随着采收时间的推迟呈先升高后降低的趋势。与当地习惯采收时间相比,推迟采收的烟叶淀粉和总氮含量普遍降低,可溶性总糖和还原糖含量升高,烟碱积累增加。上部叶淀粉酶活性与淀粉含量呈显著负相关,其硝酸还原酶活性与总氮含量呈极显著正相关;腰叶硝酸还原酶活性与淀粉含量呈极显著负相关,而与其烟碱含量呈极显著正相关;下二棚叶淀粉酶活性与总糖、烟碱含量呈极显著正相关,而与总氮、蛋白质含量呈极显著负相关。在当前的烟叶采收标准下,脚叶采收时间适宜,下二棚以及中上部叶宜推迟5～10 d采收,同时提出了广东烟区烟叶成熟的外观特征。

To investigate the appearance characteristics of fully mature flue-cured tobacco leaves growing m Guangdong, the effects of harvesting time on the enzymes key to carbon and nitrogen metabolism and main chemical components in flue-cured tobacco were studied with field experiments. The results showed that： except for middle leaves, the amylase activity in tobacco leaves increased gradually, while nitrate reductase （NR） activity in tobacco leaves raised first, then declined with the delay of harvesting time. The delay of harvesting time was beneficial to reducing starch and total nitrogen contents, increasing total sugar and reducing sugar contents, and promoting nicotine accumulation. In upper leaves, amylase activity significantly negatively correlated to starch content, while NR activity extremely significantly positively correlated to total nitrogen content. In middle leaves, NR activity extremely significantly negatively correlated to starch content, while extremely significantly positively correlated to nicotine content. In lugs, amylase activity extremely significantly positively correlated to total sugar and nicotine contents, while extremely significantly negatively correlated to total nitrogen and protein contents. The current standard of leaf harvesting was proper for flyings, however, itwas recommended to delay for 5-10 days for lugs, middle and upper leaves. Meanwhile, the appearance characteristics of mature flue-cured tobacco leaf in Guangdong were proposed.