海拔高度和移栽期对烤烟烟碱含量及其氮素来源的影响

Effects of Altitude Height and Transplanting Date on Nicotine Concentrations and Sources of Nicotine-N in Tobacco (Nicotiana tabacum L.) Plants

[目的]探讨环神农架烟区适宜的植烟海拔高度和移栽期,为"金神农"优质烤烟生产提供理论依据。[方法]采用15N同位素示踪微区试验与田间试验,研究了2个不同海拔高度(903和1130m)和3个不同移栽期(5月5、15、25日)对烤烟烟碱含量及其氮素来源的影响。[结果]烤烟吸收的土壤氮和肥料氮用于烟碱合成的比例随生育期的推进而逐渐增加,而地上部各器官烟碱氮中来源于肥料氮的比例则与之相反。与低海拔地区相比,高海拔地区烤烟各生育期体内吸收的肥料氮和土壤氮用于烟碱合成的比例分别降低了1%～29%和5%～47%;打顶期～成熟期,上、中、下部叶中肥料氮占烟碱氮的比例分别降低了41%～56%、32%～24%、22%～33%,从而导致烟碱含量降低了11%～35%。推迟移栽期降低了烤烟体内吸收的肥料氮和土壤氮用于烟碱合成的比例及烟叶中烟碱氮来源于肥料氮的比例,从而降低了烟叶中的烟碱含量。与5月5日移栽相比,5月15～25日移栽烤烟上、中和下部叶烟碱含量分别降低了8%～19%、12%～22%和12%～40%;但与5月15日移栽相比,5月25日移栽烤烟上、中部叶中烟碱含量有增加趋势。[结论]适当提高植烟海拔高度和推迟移栽期至5月15日左右更有利于降低烟叶中烟碱含量,尤其是上、中部叶。

[Objective] The aim was to study the proper altitude height and transplanting date around Shennongjia region. [Method] A field experiment with ^15N isotope tracing micro-plots was carried out to study the effects of two different altitude heights （903 and 1 103 m） and three transplanting dates （May 5, 15 and 25 ） on nicotine concentrations and sources of nicotine-N in tobacco plants. [ Result] The results showed that the proportion of fertilizer-N and soil-N which absorbed by tobacco plants, increased with the plants growing, yet the proportion of ^15 N-nicotine to total nicotine-N decreased. Compared with lower altitude height, the proportion of fertilizer-N and soil-N, which absorbed by tobacco plants in higher altitude height, decreased by 1% -29% and 5% -47%, the proportion of ~5 N-nicotine to total nicotine-N in upper, middle and lower leaves decreased by 41% -56% , 32% -24% and 22% -33% respectively, so the nicotine concentration decreased by 11% -35 %. Moreover, postponing the transplanting date decreased the proportion of fertilizer-N and soil-N absorbed by tobacco plants and the proportion of JSN-nicotine to total nicotine-N and also nicotine concentrations in tobacco leaves. Compared with the transplanting date 5＇h May, postponing thr transplanting date to 15^th- 25^th May, nicotine concentrations of upper, middle and lower leaves decreased 8% - 19%, 12% -22% and 12% -40%, however, the nicotine concentrations in upper and middle leaves of tobacco plants transplanted in 25^th May were higher than that transplanted in 15＇h May. [ Conclusion ] Improving altitude height properly and postponing the transplanting date to 15th May or so were advantage of decreasing the nicotine concentrations of tobacco leaves, especially in upper and middle leaves.