缺镁对北碚447锦橙光合作用特性的影响

Effect of magnesium deficiency on photosynthesis characteristic of Beibei 447 Jinchen orange

以北碚447锦橙为材料,测定叶片镁质量分数、光合色素质量分数、光响应和CO2响应有关指标,研究在自然条件下缺镁对锦橙叶片光合特性的影响。结果显示,随着黄化程度增加叶片的镁质量分数显著降低,叶片受镁胁迫程度加剧。随着缺镁程度增加,叶片光合色素呈极显著的下降趋势,叶片的光饱和点、Pnmax、表观量子效率(AQY)、CO2饱和点和羧化效率(CE)显著降低,叶片的光补偿点和CO2补偿点显著提高;在光响应和CO2响应上,随着缺镁程度增加,锦橙叶片气孔导度显著降低,而细胞间隙CO2显著增大,表明缺镁锦橙的光合作用主要是受非气孔限制。这些结果为柑橘优质、高产栽培提供了理论指导和相关依据。

In order to elucidate the photosynthesis characteristics of Beibei 447 Jinehen orange （Citrussinensis Osbeck） under magnesium（Mg） deficiency stress, we measured Mg content, chlorophyll content,light response and CO2 response of the leaves with different Mg deficient levels. The results revealed that the magnesium content of the leaves showed a significant downward trend with the increment of leaf yellowing degree ; those having deep yellowing leaves were stressed heavily by Mg deficiency. Photosynthetic pigment,the light saturation point, maximum net photosynthetic rate （Pn）, the apparent quantum efficiency （AQY）, CO2 saturation point and carboxylation efficiency （CE）decreased significantly with Mg deficient degree of leaves increasing. At the same time, Mg deficiency remarkably increased the light compensation point and CO2 compensation points. Furthermore,in response of light and CO2 concentration, the stomatal conductance of leaves decreased significantly, but the intracellular CO2 concentration increased remarkably with the magnesium content of the leaves decreasing, which indicated that the photosynthesis of Jincheng orange under Mg deficient stress was mainly due to non-stomatal limitation. The present study provides the theoretical guidance and related basis for citrus quality and high-yield cultivation.