光、氮及其互作对烤烟含氮化合物含量、抗氧化系统及品质的影响

Effects of Cooperation of Light and Nitrogen on the Content of Nitric Compound,Antioxidant System and Quality of Flue-cured Tobacco

【目的】揭示光照强度和氮素水平对烤烟含氮化合物形成与积累及叶片衰老的调控效应,探明适宜烤烟生长的最佳光氮条件。【方法】以烤烟品种"豫烟5号"为供试材料,采用4种光照强度和3种氮素水平的复因子盆栽试验,分析光氮互作对烤烟含氮化合物及衰老指标的影响。【结果】烤烟的硝酸还原酶(NR)、游离氨基酸(FAA)、可溶性蛋白(SP)含量在整个生育期内呈先上升后下降趋势,遮阴和增加施氮量有利于烤烟含氮化合物含量的增加,提高氮代谢水平。中、低氮处理的NR活性高峰出现在移栽后45d,高氮处理则出现在移栽后60d,表明氮代谢转向碳代谢的时间推后。遮阴处理的烤烟适当增施氮肥有利于延缓叶片衰老,遮阴处理L2(70%光照强度)的超氧化物歧化酶(SOD)活性最高且丙二醛(MDA)含量最低,说明适度弱光可提高烤烟的抗氧化能力,延长叶片功能期。随光强减弱和施氮量增加,烟碱、总氮含量上升,碳水化合物含量下降,总体上呈现氮代谢强于碳代谢的趋势。【结论】光氮互作效应对烟株体内代谢活动和衰老进程影响显著,在同一氮素水平下适度减弱光照(本试验70%光照强度)和在弱光条件下增施氮肥,能够有效地提高烟株的抗衰老能力及氮代谢强度,有利于延缓叶片衰老,高氮处理的烟株氮代谢滞后影响了碳氮代谢平衡,而中、低氮条件下氮代谢及时转入碳代谢,有利于品质形成。

Objective Nitrogen metabolism plays an important role in growth and development as well as in yield and quality of flue-cured tobacco.It is necessary to study the interaction effects of light intensity and nitrogen supply on the formation and accumulation of nitric compounds and senescence of flue-cured tobacco.A systematic experiment was conducted on the farm of Henan Agricultural University during 2008-2009 in order to elucidate a feasible combination of light and nitrogen by which the growth of flue-cured tobacco could be better advanced.Method With Yuyan 5（Nicotiana tobacum L.） as an experimental material,two elements including light intensity（four levels） and nitrogen supply（three treatments） were designed in a pot experiment to study the effects of the cooperation of light and nitrogen on the dynamic changes of nitric compounds and senescence characteristics in flue-cured tobacco.Result The content of nitrate reductase（NR）,free amino acids（FAA）,soluble protein（SP） increased first and then decreased in the whole growth period.With the increasing rate of nitrogen and shading,the activity of nitrate reductase reached the maximum at 45 days after transplant in N1,N2 and 60 days after transplant in N3,showing that the nitrogen metabolism was postponed.The activity of superoxide dismutase（SOD） was the maximum and the amount of malondialdehyde（MDA） was the lowest when the light level was at 70% of the natural light transmittance,a moderate low-light could increase the antioxidant capacity of flue-cured tobacco.The results also showed that the contents of total nitrogen and nicotine increased with the increasing rate of shading and nitrogen,but the content of carbohydrate reduced.Generally,the nitrogen metabolism was likely stronger than the carbon metabolism.Conclusion Light,nitrogen and their interactions had a significant influence on nitric compounds and senescence index of flue-cured tobacco.With 70% of the natural light intensity（in this experiment）,proper application of nitrogen in the low light intensity could improve the degree of nitrogen metabolism and delay aging of flue-cured tobacco leaves,nitrogen metabolism was postponed at high nitrogen levels so that the balance of carbon-nitrogen metabolism was broke,but the timely conversion of nitrogen metabolism to the carbon metabolism at low and moderate nitrogen levels promoted the quality of flue-cured tobacco.