Bahamonde Héctor A, Gil Luis, Fernández Victoria
Instituto Nacional de Tecnología Agropecuaria, Buenos Aires, Argentina.
Department of Natural Resources, Universidad Nacional de la Patagonia Austral, Río Gallegos, Argentina.
Front Plant Sci. 2018 Apr 18;9:494. doi: 10.3389/fpls.2018.00494. eCollection 2018.
Plant surfaces have a considerable degree of chemical and physical variability also in relation to different environmental conditions, organs and state of development. The potential changes on plant surface properties in association with environmental variations have been little explored so far. Using two model tree species (i.e., , sessile oak and , beech) growing in 'Montejo de la Sierra Forest,' we examined various traits of the abaxial and adaxial surface of leaves of both species collected at a height of approximately 15 m (top canopy), versus 3.5-5.5 m for beech and sessile oak, lower canopy leaves. Leaf surface ultra-structure was analyzed by scanning and transmission electron microscopy, and the surface free energy and related parameter were estimated after measuring drops of 3 liquids with different degrees of polarity and apolarity. The permeability of the adaxial and abaxial surface of top and bottom canopy leaves to CaCl was estimated by depositing 2 drops of 3-4 μl per cm and comparing the concentration of Ca in leaf tissues 24 h after treatment, and also Ca and Cl concentrations in the washing liquid. Higher Ca concentrations were recorded after the application of CaCl drops onto the veins and adaxial blade of top canopy beech leaves, while no significant evidence for foliar Ca absorption was gained with sessile oak leaves. Surprisingly, high amounts of Cl were recovered after washing untreated, top canopy beach and sessile oak leaves with deionised water, a phenomenon which was not traced to occur on lower canopy leaves of both species. It is concluded that the surface of the two species analyzed is heterogeneous in nature and may have areas favoring the absorption of water and solutes as observed for the veins of beech leaves.
植物表面在化学和物理性质上也存在相当大的变异性，这与不同的环境条件、器官和发育状态有关。迄今为止，与环境变化相关的植物表面特性的潜在变化鲜有研究。我们利用生长在“蒙特霍·德拉谢拉森林”中的两种模式树种（即无柄栎和山毛榉），研究了这两个树种在大约15米高度（树冠顶部）采集的叶片正反两面的各种性状，而山毛榉和无柄栎下层树冠叶片的采集高度为3.5 - 5.5米。通过扫描电子显微镜和透射电子显微镜分析叶片表面超微结构，并在测量了3种具有不同极性和非极性程度的液体的液滴后，估算表面自由能及相关参数。通过每平方厘米沉积2滴3 - 4微升的氯化钙，并比较处理后24小时叶片组织中钙的浓度以及洗涤液中钙和氯的浓度，来估算树冠顶部和底部叶片正反两面对氯化钙的渗透性。在山毛榉树冠顶部叶片的叶脉和叶片正面滴加氯化钙后，记录到较高的钙浓度，而无柄栎叶片未获得明显的叶面钙吸收证据。令人惊讶的是，用去离子水冲洗未经处理的树冠顶部山毛榉和无柄栎叶片后，回收了大量的氯，而在这两个树种的下层树冠叶片上未发现这种现象。得出的结论是，所分析的这两个树种的表面本质上是异质的，并且可能存在有利于吸收水分和溶质的区域，如山毛榉叶片的叶脉。
