不同生态区烤烟叶片稳定碳同位素组成特征

Stable carbon isotope composition of tobacco leaves in different ecological regions

在河南、福建和云南3个生态区大田种植烤烟K326,采集不同叶位生理成熟的烟叶,测定δ13C值、总碳、全氮及比叶重,探讨了不同生态区烟叶δ13C值组成特征。结果表明:河南烟叶δ13C值分布范围为-31.2%—-27.3‰,平均值-29.7‰;福建烟叶δ13C值分布范围为-28.6%—-24.6‰,平均值-26.3‰;云南烟叶δ13C值分布在-27.1—-24.0‰之间,平均值-25.6‰;河南烟叶全氮含量最高,其总碳、碳氮比和比叶重均显著低于其余两地;福建和云南烟叶各生理指标值较为接近;各生态区烟叶δ13C值均与全氮含量呈负相关,与碳氮比及比叶重呈正相关。河南与其余两地烤烟生理特征的差异性,以及福建与云南烤烟生理特征的相似性表明,δ13C值可能与烤烟的品质存在关联。

The quality of crops attracts the attention of many scholars,and tobacco crops are no exception. Tobacco produced in the Fujian and Yunnan ecological regions is distinguished by its delicate fragrance,while tobacco produced in Henan is famous for its strong aroma. Research has shown that meteorological factors cause these differences,although evaluating how the meteorological conditions of any ecological particular region influence the flavor of tobacco has proved difficult. However,use of the stable carbon isotope technique,which has been widely used in ecological studies,provides a possible approach for solving the above problem. Many studies have demonstrated that the amount of δ^13C（ stable carbon isotope composition） found in plants is influenced by environmental conditions, such as temperature, moisture,illumination,and so on. In addition,δ^13C has been closely connected with various physiological characteristics. Therefore,the amount of δ^13C found in plants could be a link between environmental conditions in a region and the resulting physiological characteristics of individual plants. This paper investigates the distribution of δ^13C in the ecological regions of Henan,Fujian and Yunnan provinces,China. We also wanted to know if the amount of δ^13C found in plants could be used to evaluate the effect of the environment on the quality of tobacco. The Tobacco cultivar K326 was planted in three different ecological regions; one test site was located in each of three provinces,Henan,Fujian and Yunnan. During the tobacco growing season,the Fujian and Yunnan test zones have adequate precipitation and low average temperatures（20. 8 ℃ and22. 8 ℃,respectively） in contrast to the Henan test zone,which has sparse precipitation and high temperatures（25. 7 ℃）that are not as favorable for growing tobacco. Mature leaves from different leaf positions（ from ground to top,selecting the 7^th,10^th,13^th and 16^th leaf from tobacco plants） were collected as test samples; then,δ^13C,total organic carbon,total nitrogen and LMA（ leaf mass per area） were determined. The results suggested that the δ^13C levels in both Yunnan and Fujian tobacco increased with leaf position. The δ^13C of Henan tobacco did not exhibit this trend. The δ^13C in samples from the Henan test zone ranged between- 27. 3 ‰ and- 31. 2 ‰,averaging- 29. 7 ‰. The δ^13C in samples from the Fujian and Yunnan test zones had similar levels and were between- 24. 0 ‰ and- 27. 1 ‰ and between- 24. 6 ‰ and- 28.6 ‰,respectively,averaging- 26. 3 ‰ and- 25. 6 ‰,respectively. Henan tobacco had the highest leaf total nitrogen content,but the total organic carbon content,C / N ratio and LMA were lowest in Henan tobacco. However,the data for each measurement of Fujian＇ s and Yunnan＇ s tobacco leaves were quite similar. Additionally,while Fujian and Yunnan tobacco obviously had similar physiological characteristics,they were quite different from Henan tobacco. The correlation analysis suggested that δ^13C was negatively correlated with total nitrogen,and positively correlated with the C / N ratio and LMA. In conclusion,based on the relationships of δ^13C with total organic carbon and total nitrogen,δ^13C could provide a link for biochemical coupling between nitrogen and carbon metabolism. Plastid segments,nicotine,protein and neutral aroma constituents,which are known to be decisive factors that determine tobacco quality,were all allied to nitrogen and carbon metabolism. That is,the results verified our hypothesis that δ^13C could be a link between meteorological factors and tobacco quality. In summarizing the above arguments,we believe that δ^13C can be used to evaluate the effects of environmental variables on tobacco quality.