缺镁对龙眼光合作用的影响

The Effect of Magnesium Deficiency on Photosynthesis of Longan( Dimocarpus longana Lour.)Seedlings

缺镁胁迫下 ,龙眼 (DimocarpuslonganaLour .)幼苗叶片光合色素含量、叶绿体对光吸收能力、表观量子产量和羧化效率下降 ;光补偿点和CO2 补偿点提高 ,光饱和点和CO2饱和点下降 ;Chl.a荧光动力学参数Fv/Fo、Fv/Fm和Fd/Fs的降低说明缺镁龙眼PSⅡ活性下降 ;F685/F73 6比值的下降则表明缺镁降低了激发能在两个光系统之间分配的调节能力。

The effect of magnesium deficiency on photosynthesis of longan( Dimocarpus longana Lour.)seedlings was studied using hydroponic experiment.Magnesium deficiency led to the decline of the contents of chlorophyll and carotenoid,the capability of light energy absorption of chloroplast as well as maximum photosynthesis at both light and CO 2 saturation conditions.On the other hand,the apparent quantum yield,carboxylation efficiency and both light and CO 2 compensation points turned out to become higher as magnesium become deficient.The results of chlorophyll a fluorescence induction measurement showed a decrease of Fv/Fo,Fv/Fm and Fd/Fs in magnesium deficient longan leaves,indicating that primary light energy conversion ability and potential photosynthetic activities of PSⅡ were inhibited.The decrease in F 684 /F 736 under magnesium deficiency condition suggested that the regulation of excitation energy distribution between PSⅡ and PSⅠ was reduced.The discussion was made on the responsive mechanism of longan to magnesium deficiency.