Physiological Effect of Magnesium in Relieving Temperature-and-light-induced Damage to Tobacco Plants

  Objective   Application of magnesium to alleviate the physiological damage that seriously ill-affects the yield and quality of a tobacco plant by high temperature and strong light was studied.

  Method   Flue-cured tobacco, Cuibi No. 1 (Nicotiana tabacum), plants were supplied with magnesium at 0, 12.0, 48.0, and 120.0 mg·L⁻¹ under 33 ℃ with light exposures of 600 or 1 200 µmol·m⁻²·s⁻¹. Effects of the nutrient supplement on the physiology of tobacco plants were monitored.

  Result   A magnesium deficiency on the plants with the symptoms of sun-burn, H₂O₂ and malondialdehyde accumulations, and a heightened leaf membrane permeability was observed under the stress of 33 ℃ and the light exposure at 1 200 µmol·m⁻²·s⁻¹. Through supplementing 48 mg·L⁻¹ magnesium the tobacco plants significantly rose on the activities of superoxide dismutase and catalase, which eliminated ROS, as well as the chlorophyll content and net photosynthetic rate. The adverse effects caused by the stress were significantly relieved.

  Conclusion  Appropriate application of magnesium fertilization could alleviate the physiological damages on tobacco plants caused by high temperature and strong light exposure.