缺镁对龙眼光合产物生产和分配的影响

EFFECTS OF MAGNESIUM DEFICIENCY ON THE YIELD AND DISTRIBUTION OF PHOTOSYNTHATE OF LONGAN ( Dimocarpus longana LOUR)

缺镁对龙眼 (DimocarpusLonganaLour.)光合产物的生产和分配有明显的影响。缺镁胁迫下 ,龙眼叶片单位面积和单位重量的叶绿素、类胡萝卜素含量均降低 ,光合速率下降 ,叶绿体亚显微结构发生明显的改变 ,叶绿体中可见有大量的淀粉粒。随着缺镁胁迫程度的加重 ,14 C -光合产物在标记叶中的滞留量增加 ,输出率降低。叶片非还原糖、淀粉含量增加 ,茎秆、根系的非还原糖尤其是淀粉含量降低。

The effects of magnesium deficiency on the yield and distribution of photosynthate in longan( Dimocarpus Longana Lour)young seedling were studied using hydroponic experiment. Under magnesium deficiency stress,not only the contents of chlorophyll and carotenoid per unit area and per unit fresh weight in leaves were reduced,but also the rate of photosynthesis was reduced.Magnesium deficiency had markedly effects on chloroplast ultrastructure of longan.The chloroplast suffering from magnesium deficiency was distinguished by an accumulation of starch vacuoles.Magnesium deficiency stress increased the proportion of 14 C photosynthate remaining in labelled leaves and decreased the rate of 14 C photosynthate exportation.The inhibition of 14 C photosynthate exportation in magnesium deficient plant coincided with the increase of sucrose,starch concentration in leaves,and with the decrease of sucrose,starch concentration in shoots and roots as compared with normal plant.Discussion was made on the responsive mechanism of longan photosynthate production and distribution to magnesium deficiency.