不同光强和缺镁胁迫对黄瓜叶片叶绿素荧光特性和活性氧产生的影响

Effect of light intensity and magnesium deficiency on chlorophyll fluorescence and active oxygen in cucumber leaves

不同光强和镁离子浓度对黄瓜叶片叶绿素荧光特性和活性氧产生的影响研究发现 ,在强光和缺镁胁迫下 ,黄瓜叶片发生了明显的光抑制 ,主要表现为Pn下降 ,叶绿素荧光参数Fv/Fm、Fv/Fo、qP和 qN降低 ;活性氧超氧阴离子产生速率和H2 O2 以及膜脂过氧化产物MDA增加。这些结果表明 ,缺镁黄瓜叶片在强光下qP和 qN的降低使叶片吸收的过剩光能通过光化学反应途径和非辐射能量途径耗散受阻 ,从而增加了过剩光能所激发的电子用来生成活性氧的比例 ,这在一定程度上可缓解光抑制 ;但其不能被及时清除掉时 ,会加剧光抑制 ,甚至引起光氧化对光合机构造成破坏 ,最终导致叶片的失绿坏死。适当遮荫有利于提高PSII的光化学效率 ,减轻光抑制。

Effects of different light intensities and Mg 2+ concentrations on chlorophyll fluorescence and active oxygen in cucumber leaves were studied. The results showed that high light intensity and Mg deficiency induced obvious photoinhibition, which was mainly exhibited by the decrease of the photosynthetic rate (Pn), chlorophyll fluorescence parameters such as Fv/Fm, Fv/Fo, qP and qN, and the increase of O -· 2 producing rate, H 2O 2 and MDA contents. Adequate shading would help to increase photochemical efficiency of PSII and reduce photoinhibition.