Abstract: In order to investigate curing characteristics of upper tobacco leaves, the difference of water loss rate, yellowing and browning characteristics, chlorophyll relative content (SPAD), color values, polyphenol oxidase (PPO) activity and chemical composition content of the different maturity leaves of K326, Bi’na1, Zunyan6, Guiyan1, Guiyan4 and Honghuadajinyuan (Hongda) were studied during curing or during drawer testing. The results showed that Bi’na1 had smaller water loss rates while Hongda and Guiyan1 had larger water loss rates; Bi’na1 and K326 had shorter yellowing time while Hongda had a longer yellowing time during curing and drawer testing. The average PPO activity of Bi’na1 was less than 0.4 U and that of Guiyan1 was larger than 0.5 U during curing. As for chlorophyll relative content, Hongda had larger SPAD values, then were Zunyan6 and Guiyan1, and the last were Bi’na1, Guiyan4 and K326 during drawer testing. Hongda and Zunyan6 showed a relatively poor color values, and Guiyan1 showed a more serious browning. However, Bi’na1 had a lighter browning during drawer testing. Moreover, flue-cured tobacco leaves of Bi’na1, Guiyan4 and Zunyan6 had a relatively suitable chemical composition content. Following progressive improvement of tobacco leaves maturity levels, the yellowing time of fresh tobacco leaves was shortened and the activity of PPO increased during curing, the total content plant alkaloid and nitrogen decreased, and the content of water-soluble total sugar and reducing sugar increased. In addition, the yellowing time and browning time of tobacco leaves were shortened, the SPAD value was reduced, and the color showed better before the leaf became browning with the improvement of tobacco leaf maturity levels during drawer testing. Variety and maturity not only affected the leaf phenotype, but also had a significant impact on its intrinsic physiology. The curing characteristics of different flue-cured tobacco varieties were not only closely related to the chemical composition, but also the genotypes. As for drawer testing, SPAD value could be used as a phenotypic indicator for judging the easy curing portential, and the color parameters could be used as a phenotypic indicator for judging the easy and endurable curing portential. Taken together, K326, Bi’na1, Guiyan1 and Guiyan4 had a better easy curing portential, then was Zunyan6, and Hongda showed the worst performance. In addition, Bi’na1 had a better endurable curing portential, then were K326, Guiyan4, Hongda and Zunyan6, and Guiyan1 showed the worst performance. According to the difference of curing characteristics of different flue-cured tobacco varieties, we have put forward some specific measures for different tobacco varieties curing, which lay the theoretical foundation for different flue-cured tobacco varieties curing and the improvement of upper tobacco quality.

Key words: flue-cured tobacco, variety, upper leaves, maturity, curing characteristics

摘要： 为明确烤烟叶片上部叶烘烤特性,以K326、毕纳1号、遵烟6号、贵烟1号、贵烟4号、红花大金元(红大)不同成熟度上部叶为材料,研究比较了烘烤或暗箱试验中烟叶失水速率、变黄变褐特性、叶绿素相对含量(SPAD)、颜色值、多酚氧化酶(PPO)活性以及烤后烟叶化学成分含量的差异。结果表明,烘烤和暗箱试验中毕纳1号失水速率较小,红大和贵烟1号失水速率较大,毕纳1号和K326变黄时间最短,红大变黄时间最长;烘烤过程中毕纳1号PPO活性均值低于0.4 U,贵烟1号高于0.5 U;暗箱试验中红大SPAD值较大,其次是遵烟6号和贵烟1号,毕纳1号、贵烟4号、K326较小,红大和遵烟6号颜色值相对较差,毕纳1号变褐较轻,贵烟1号变褐最严重;烤后烟叶毕纳1号、贵烟4号和遵烟6号化学成分含量相对适宜。随着烤烟叶片成熟度的提高,烘烤试验中烟叶变黄时间缩短,PPO活性增加,烤后烟叶总植物碱、总氮含量降低,水溶性总糖、还原糖含量增加;暗箱试验中烟叶变黄、变褐时间缩短,SPAD值减小,颜色较好,但变褐后颜色较差。品种与成熟度不仅影响烟叶的外观表型,而且显著影响其内在生理。不同烤烟品种烘烤特性与化学成分和基因型均密切相关。对于暗箱试验,SPAD值可作为烟叶易烤性的表型判断指标,颜色参数可作为易烤性和耐烤性的表型判断指标。综合来看,K326、毕纳1号、贵烟1号、贵烟4号上部叶易烤性较好,遵烟6号较差,红大最差;毕纳1号上部叶耐烤性较好,其次是K326、贵烟4号、红大和遵烟6号,贵烟1号最差。根据不同烤烟品种烘烤特性差异,本研究有针对性地提出了上部叶烘烤工艺措施,为烤烟品种烘烤和上部叶品质提升奠定了理论基础。

关键词: 烤烟, 品种, 上部叶, 成熟度, 烘烤特性