龙眼叶片冻害症状及细胞超微结构变化

以石硖龙眼为试材,于霜冻期间取叶片作超薄切片电镜透射观察,同时对叶片冻害症状进行观察,结果表明:龙眼叶片结霜时细胞结构尚未受到明显破坏,叶片外部亦未表现出明显的冻害症状。在霜晶快速溶化后细胞结构受破坏,出现质壁分离、细胞膜破裂等现象,从而导致细胞液大量外流,叶片出现褐色或黑褐色冻斑。随着阳光照射和气温继续升高,受冻害的叶片进一步失水,导致细胞壁破裂,细胞质、细胞器等原生质裂解、互溶,使细胞结构发生不可逆转的变化,致使细胞死亡。

Frosted symptom and ultrastructural changes of longan leaf

The frosted leaf ultrastructures of longan named‘Shixia’were detected under electron microscope and the freezing injury symptoms were observed. The results indicated that there were not obvious damages in cellular structure when leaves were frosted,and the freezing injury symptoms of outer part of leaves were not obvious. But the ultrastructures were damaged when frost crystal dissolved fleetly,such as plasmolysis,membranolysis and cytoplasm flowing out,which caused the phenomenon of brown or black-brown frost spots. With the sunlight exposure and the increase of air temperature,the frosted leaves dehydrated further,cell wall ruptured,and cytoplasm clearaged or dissolved,which led to the reversibly changes of cellular structure,then the cell died.