5个龙眼品种叶片结构研究

Observational study on leaf structures of five Longan cultivars

为研究不同龙眼品种的叶片结构及差异性,以仲恺农业工程学院钟村农场果树标本园的5个龙眼品种为试材,通过石蜡切片、扫描电镜和离析法对5个品种的叶片组织结构进行观察,同时对叶片结构进行分析。结果表明,各龙眼品种叶片均为异面叶,上下表皮由单层细胞组成;下表皮密布乳状突起,每一乳状突起均由呈管状的细胞围绕而成;气孔仅分布在下表皮,主要在各级侧脉附近。不同品种在叶片厚度、上表皮角质层厚度及气孔长轴等方面无显著差异,但不同品种的栅栏组织厚度、海绵组织厚度、栅/海比、乳状突起密度及气孔短轴存在差异。龙眼叶片气孔数量少。不同龙眼品种叶片结构的差异性可以为龙眼种质资源的鉴定和开发利用提供依据。

The objective of the study is to elucidate the differences among the leaf structures of longan cultivars.Taking Dimocarpus longan Lour.＇Chuliang＇,D.longan Lour.＇Dawuyuan＇,D.longan Lour.＇Fuyan＇,D.longan Lour.＇Guihua＇,D.longan Lour.＇Shixia＇ as materials,and they were compared under paraffin section,scanning election microscope and maceration.The leaf structure parameters were measured and analyzed.The results showed that the leaf was typical bifacial,the upper and lower epidermis were consisted of monolayer of cells,the upper epidermis cells arranged regularly,the lower epidermis cells were uneven;the lower epidermis was covered with numerous mammillae,each mammilla was composed of a number of tubular cells;stomas were few and only distributed on lower epidermis,mainly near lateral veins.Leaf thickness,horny layer thickness and stoma long axis of five longan cultivars had no significant difference.The thickness of upper epidermis cells,palisade tissue,spongy tissue,and the value of palisade tissue thickness/spongy tissue thickness,mammilla density,stoma short axis had significant differences among different longan cultivars.It was only a few stomas that we observed on the lower epidermis of the leaves.The lower epidermis was covered with numerous mammillae.The results can provide basis for the identification and development of longan germplasm resources.