Zhao Wanli, Fu Peili, Liu Guolan, Zhao Ping
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China.
AoB Plants. 2020 Sep 11;12(5):plaa047. doi: 10.1093/aobpla/plaa047. eCollection 2020 Oct.
Emergent aquatic plants mostly occur in shallow waters and root in bottom substrates, but their leaves emerge from the water surface and are thus exposed to air, similar to the leaves of terrestrial plants. Previous studies have found coordination between leaf water supply and demand in terrestrial plants; however, whether such a coordination exists in emergent aquatic plants remains unknown. In this study, we analysed leaf veins and stomatal characteristics of 14 emergent aquatic and 13 terrestrial monocotyledonous herb species (EMH and TMH), with 5 EMH and 8 TMH belonging to Poaceae. We found that EMH had significantly higher mean leaf area, leaf thickness, stomatal density, stomatal number per vein length and major vein diameter, but lower mean major vein length per area (VLA) and total VLA than TMH. There was no significant difference in stomatal length, minor VLA and minor vein diameter between the two groups. Stomatal density and total VLA were positively correlated among the EMH, TMH, as well as the 8 Poaceae TMH species, but this correlation became non-significant when data from both the groups were pooled. Our results showed that the differences in water supply between emergent aquatic and terrestrial plants modify the coordination of their leaf veins and stomatal traits.
挺水水生植物大多生长在浅水区，根系扎入底部基质，但它们的叶子露出水面，因此与陆生植物的叶子一样暴露在空气中。先前的研究发现陆生植物叶片的水分供需之间存在协调关系；然而，这种协调关系在挺水水生植物中是否存在仍不清楚。在本研究中，我们分析了14种挺水水生单子叶草本植物（EMH）和13种陆生单子叶草本植物（TMH）的叶脉和气孔特征，其中5种EMH和8种TMH属于禾本科。我们发现，与TMH相比，EMH的平均叶面积、叶厚度、气孔密度、单位叶脉长度的气孔数量和主脉直径显著更高，但单位面积的平均主脉长度（VLA）和总VLA更低。两组之间的气孔长度、小叶脉VLA和小叶脉直径没有显著差异。EMH、TMH以及8种禾本科TMH植物中，气孔密度和总VLA呈正相关，但将两组数据合并后，这种相关性变得不显著。我们的结果表明，挺水水生植物和陆生植物在水分供应上的差异改变了它们叶脉和气孔特征的协调性。
