墨兰幼叶和成熟叶不同部位叶绿体超微结构和光合作用

墨兰试管苗植株成熟叶片叶绿体基粒较发达，类囊本膜垛叠较紧密。幼叶叶绿体中少有亲锇颗粒，成熟叶的叶绿体中往往既有亲锇颗粒又有淀粉粒。幼叶中基粒数目比成熟叶的少，叶绿体也比成熟叶的小。幼叶的光合放氧速率比成熟叶的低。幼叶中叶尖部叶绿体最大而叶基部最小，但叶尖部的光合放氧速率比叶基部小。成熟叶中叶绿体大小及光合放氧速率区别不明显。通过对各部位叶绿素含量的测定发现，叶绿素含量与光合放氧速率之间没有正相关性

ULTRASTRUCTURE OF CHLOROPLASTS AND PHOTOSYN-THESIS IN DIFFERENT SECTIONS OF YOUNG AND MATURE LEAVES OF CYMBIDIUM SINENSE (ANDR.) WILLD.

Ultrastructural observation of chloroplasts in different sections of young and mature leaves of Cymbidium sinense (Andr.) Willd. showed that the grana in chloroplasts of mature leaves were well developed, with tight thylakoid membrane. Osmiophilic granules in young leaves were few, whereas those in mature leaves were many, and so were the starch grains. In comparison with mature leaves, fewer grana, smaller chloroplasts and lower photosynthetic oxygen evolution rate were found in young leaves. In young leaves, chloroplasts in leaf apex were biggest, and in leaf base, smallest, but lower oxygen evolution rate was shown in leaf apex. No significant difference was found in chloroplast size and chlorophyll content among various parts of mature leaves. Chlorophyll content is not in direct proportion to oxygen evolution rate.