| Reducing nicotine content in tobacco leaves has become an important consideration for the international community in trying to reduce tobacco consumption,in order to explore a new way to regulate nicotine content in tobacco leaves,tobacco intertype grafting,tobacco interspecific grafting and low-nicotine cultivation mode planting experiments were conducted in Xiangcheng County,Xuchang City and climate Room of National Tobacco Cultivation Physiology and Biochemistry Research Base,Henan Agricultural University from 2019 to 2022 to study the changes of tobacco leaf agronomic traits,alkaloids and other conventional chemical components and sensory quality.In order to through agricultural measures to reduce and adjust the content of nicotine to provide technical support,the main results were as follows:(1)The difference in agronomic traits of different varieties was small under LBP,but the effect of LNM on their later growth period was significant.The alkaloid contents of the three varieties varied greatly under LBP.The nicotine contents of the upper and middle leaves of NC926 were 0.28% and 0.21% respectively.The content of nicotine and total alkaloid in tobacco leaves decreased significantly at LNM,but the degree of nicotine decrease in low-nicotine tobacco leaves was relatively small,the nicotine content in the upper leaves of ITB697 and NC926 decreased by 43.50% and 38.03%,respectively,and that in the middle leaves of ITB697 decreased by 23.21%,while the middle leaves of NC926 showed no significant difference,the decrease range of nicotine in high-nicotine leaves was relatively large at LNM,the upper and middle leaves of Zhongyan 100 decreased by 44.11%and 30.01% respectively.The content of reducing sugar,total sugar and total nitrogen in flue-cured tobacco leaves of different varieties at the same position were Zhongyan100>ITB697>NC926 at LNM,which could decrease the content of total nitrogen and increase the content of reducing sugar and total sugar in upper leaves,however,the contents of reducing sugar and total sugar in the middle leaves decreased.There was no significant difference in the content of neutral aroma components among different varieties under LBP.Under LNM,the total amount of neutral aroma components decreased,the quality of aroma became worse,the quantity of aroma,concentration,impact and irritancy decreased,the excitability became better and the aftertaste became lighter,at the same time,the economic characters of tobacco leaf became worse.(2)After the burley is grafted with the eggplant,there was no significant change in morphological construction and agronomic characters of burley tobacco.The content of alkaloid in fresh tobacco leaves,the content of nicotine and total alkaloid of the burley grafted with the eggplant was 94.81% and 95.10% lower than that of CK at 60 days after grafting,and the content of nicotine and total alkaloid of the grafted with the eggplant treatment was 0.080% and 0.087% at 90 days after grafting,it decreased by 97.35% and97.33% compared with CK,and the content of nicotine in upper and middle leaves decreased to 0.120% and 0.088% respectively,it decreased by 97.04% and 97.59%respectively compared with CK.The contents of total sugar,reducing sugar,starch and amino acid in grafted tobacco leaves increased,while the contents of total nitrogen and protein decreased.The contents of NNN,NNK and TSNAs in tobacco leaves after grafting and curing decreased significantly.There were no significant changes in smoke concentration and aroma quality of grafted tobacco leaves,but the quantity of aroma,vigor and irritability were decreased.(3)After grafting of oriental tobacco and burley tobacco,there was no significant change in morphological construction and agronomic characters of scions.Burley tobacco as rootstock and oriental tobacco as scion were grafted,the contents of nitrate,alkaloids and total nitrogen increased significantly,while the contents of total sugar,reducing sugar and amino acid decreased,the content of nicotine and total alkaloid in fresh tobacco leaves increased by 35.38% and 38.33%,respectively,compared with that of normal cultivated tobacco leaves,the content of nicotine and total alkaloid in fresh tobacco leaves after 90 days of grafting was 65.38% and 65.42% higher than that of normal oriental tobacco leaves,and the content of nicotine and total alkaloid in upper tobacco leaves after curing was70.74% and 75.85% higher than that of normal oriental tobacco leaves,respectively,the content of nicotine and total alkaloid in middle leaves increased by 86.88% and 90.34%,respectively.After burley tobacco was grafted on oriental tobacco stock,the contents of total sugar,reducing sugar and amino acid increased significantly,while the contents of nitrate,alkaloid and total nitrogen decreased significantly,the content of nicotine and total alkaloids in fresh tobacco leaves were 22.73% and 23.53% lower than that of normal burley tobacco at 60 days after grafting,respectively,the content of nicotine and total alkaloid in fresh tobacco leaves were decreased by 37.91% and 38.66%,respectively,compared with that of normal burley tobacco leaves at 90 days after grafting,and the content of nicotine and total alkaloid in upper leaves were decreased by 42.44% and 43.73%,respectively,the content of nicotine and total alkaloid in middle leaves decreased by 41.44% and 42.22%,respectively.After grafting with burley tobacco as rootstock,the aroma of the upper leaves increased,the vigor and irritation increased,and the vigor of the middle leaves increased;After grafting with oriental tobacco as rootstock,the upper leaves of burley tobacco scion had less aroma,less vigor and irritation,and less vigor of middle leaves.This study provided technical support for regulating nicotine content in tobacco leaf through agricultural measures,the low nicotine cultivation mode can further reduce the nicotine content of flue-cured tobacco,it will have a significant negative effect on quality and benefit of tobacco leaves.Although the grafting of burley tobacco with eggplant,burley tobacco with flavoring tobacco could change the nicotine content of tobacco leaves without affecting the agronomic characters of tobacco plants,and the contents of other chemical components and sensory quality indexes of tobacco leaves were affected to different degrees,while the alkaloid content of flue-cured tobacco could be selectively reduced significantly through genetic breeding. |
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