镁对烟草生长及叶片叶绿素荧光参数的影响

Effects of magnesium on tobacco growth and chlorophyll fluorescence parameters of tobacco leaves

通过水培试验，研究了不同镁素水平对烟草生长、叶片叶绿素含量及叶绿素荧光参数的影响，为烟草优质栽培和镁肥的合理施用提供理论依据。结果表明，营养液中镁浓度在2～4mmol／L时，烤烟的干物质积累显著高于其它处理，最适宜烟株的生长，镁浓度过高或过低都会抑制烟株的生长；营养液中镁浓度在0～2mmol／L范围内，烟草叶片叶绿素含量随镁浓度的升高而逐渐升高，但高于2mmol／L时，烟草叶片叶绿素的含量逐渐下降；营养液中镁浓度在8mmol／L时，烟草叶片量子产量（EQY）光合电子传递速率（ETR）、非光化学猝灭（NPQ）均达到最高。烟草叶片对强光有最大的适应性，缺镁和高镁均能导致烟草量子产量降低，光合电子传递受阻，减少对过剩的激发能的耗散，使植株对强光的保护性调节能力降低。

This study focused on the changes of tobacco growth, chlorophyll content and chlorophyll fluorescence of tobacco leaves under different concentration of magnesium supplementation （Mg^2＋ 0, 0.5, 1, 2, 4, 8, 16 mmol/L） using solution culture, and the results provide the theoretical foundation for rational application of magnesium fertilizer and high quality culture of tobacco. The results showed that application of Mg increased dry matter accumulation of flue-cured tobacco, with the concentration of Mg^2 ＋ 2-4 mmol/L having the highest effect. Neither too high nor too low concentration of Mg had any beneficial effect on the growth of flue-cured tobacco. Leaf chlorophyll content was increased first but decreased when the Mg^2 ＋ concentration was 〉 2 mmol/L. Chlorophyll content of tobacco leaves was decreased significantly under either Mg^2 ＋ -deficient or Mg^2 ＋ -excessive conditions. The effective quantum yield （EQY）, electron transport rate （ETR） and non-photochemical quenching （NPQ） were all the highest at the concentration of 8 mmol/L Mg^2＋ . Tobacco leaves had the largest adaptability to high light intensity at the concentration of 8 mmol/L Mg^2 ＋ . Both Mg^2 ＋ -excessive and Mg^2 ＋ -deficient conditions decreased the effective quantum yield, suffocated the electron photosynthetic rate and reduced the dissipation of excessive excitation energy.