镁营养对高温强光下烟草碳氮代谢的影响研究

为探究镁营养对高温强光胁迫下烟草碳氮代谢的影响,以烟草‘翠碧一号’为材料,设置4个镁浓度(0、12.0、48.0、120.0 mg/L)与33℃高温下2个光强600、1200 µmol/(m²·s)]处理,分析不同镁供应浓度和光强处理对烟草植株糖类物质积累、碳氮代谢生理以及钾钙含量的影响。结果表明：（1）镁供应和光强均显著影响烟株地上和地下部的蔗糖和可溶性糖含量,且光强对烟株淀粉含量也有显著影响。强光能使烟株地上和地下部可溶性糖累积,在镁营养为48.0 mg/L时地上部可溶性糖达到最大值。（2）随着镁离子浓度的增加,烟株的蔗糖合成酶(SS)、蔗糖磷酸合成酶(SPS)、酸性转化酶(AI)、谷氨酰胺合成酶(GS)和硝酸还原酶(NR)等碳氮代谢关键酶的活性呈现先升高后降低的趋势,在48.0 mg/L时活性达到最大,且强光处理下活性均高于正常光。镁浓度、光强及镁浓度×光强对烟株地上部NR、AI活性的影响均达1%极显著水平。（3）高温强光促进烟株对钾、钙离子的吸收,但随着镁离子浓度的增加,吸收受到抑制。镁浓度、光强及镁浓度×光强对地下部钾和钙含量的影响均达5%显著水平。适宜的镁营养(48.0 mg/L)增强了烟株碳氮关键酶的活性,促进了碳氮代谢,提高了可溶性糖的积累,从而缓解高温强光对烟株的伤害。

The Physiological Basis of Magnesium Recovering Tobacco Plants from High Temperature and Strong Light Stress

In this study, flue-cured tobacco ‘Cuibi No.1’ was used as the material, and four concentrations of magnesium supply (0, 12.0, 48.0 and 120.0 mg/L) and two light intensities 600 and 1200 µmol/(m²·s)] at 33℃ were designed to study the effects of magnesium supply on the physiology of tobacco plants under high light intensity and high temperature stress. The results showed that: (1) the contents of sucrose and soluble sugar in the shoots and roots of tobacco plants were significantly affected by the supply of magnesium and the intensity of light, while the starch content of tobacco plants was also significantly affected by the light intensity; high light intensity could induce the accumulation of soluble sugar in the shoots and roots of tobacco plants, and the soluble sugar in the shoots reached its maximum value under high light intensity when the magnesium supply was 48.0 mg/L; (2) with the increase of magnesium supply, the activities of key enzymes in carbon and nitrogen metabolism, including sucrose synthase (SS), sucrose phosphate synthase (SPS), acid invertase (AI), glutamine synthase (GS) and nitrate reductase (NR), increased first and then decreased, and reached the maximum at 48.0 mg/L of magnesium supply; these enzyme activities in tobacco plants under high light intensity were higher than those under normal light intensity; magnesium supply, light intensity and magnesium supply × light intensity significantly affect NR and AI activities in the shoots of tobacco plants; (3) high temperature and high light intensity enhanced the absorption of K⁺ and Ca²⁺ in tobacco plants, but the absorption was inhibited with the increase of magnesium supply; magnesium supply, light intensity and magnesium supply × light intensity significantly changed the contents of K⁺ and Ca²⁺ in the roots of tobacco plants. Appropriate magnesium supply (48.0 mg/L) could enhance the activities of key enzymes of carbon and nitrogen, promote the metabolism of carbon and nitrogen, increase the accumulation of soluble sugar, and then alleviate the damage of high temperature and high light intensity to tobacco plants.