Responses of two macrophytes of the genus Polygonum to water level fluctuations and interspecific competition

The anatomy of two species of emergent macrophytes of the genus Polygonum differentially changes in response to water‐level fluctuations

“…Plants in general and aquatic macrophytes in particular exhibit adaptive responses to waterlogging and submersion, and these adaptations are key in flooded habitats, where anoxia or hypoxia in sediment along with low CO 2 availability is common. These adaptations include anatomical and morphological changes that vary across macrophyte species of different life forms (Liu et al, 2016;Murillo et al, 2019;Scoarize, 2016). The development of aerenchyma (hereafter referred to as intercellular spaces) is a key adaptation to waterlogging and submergence because it enhances oxygen translocation to underground organs and diffusion of CO 2 (Parent et al, 2008;Raven, 1996;Sculthorpe, 1985).…”

“…Members of the Polygonaceae family colonize predominantly aquatic and semi-aquatic habitats. Some Polygonum species exhibit morphological plasticity that allows them to colonize habitats subject to natural and artificial hydrological and limnological alterations (Murillo et al, 2019;Sultan, 2001). The aquatic plants Polygonum ferrugineum Wedd.…”

“…and Polygonum acuminatum Kunth are species of Polygonaceae that occur in a variety of aquatic habitats of South America, for example, the Pantanal wetland (Pott & Pott, 2000) and the Upper Paraná River floodplain (Souza et al, 2017). A previous study demonstrated that the high abundance of these species can be related to their ability to etiolate and maintain their photosynthetic tissues above the water surface despite changes in water depth (Murillo et al, 2019). In general, this morphological adaptation can also lead to anatomical changes; however, these changes may not occur in some species if the water-level fluctuates too fast (Deegan et al, 2007).…”

“…In addition, the anatomic adaptations may differ between P. ferrugineum and P. acuminatum because they present different strategies to escape flooding. For example, P. ferrugineum produces plagiotropic branches and floats and morphological characteristics that avoid flooding stress (Murillo et al, 2019) We conducted an experimental study to measure the anatomical responses of P. ferrugineum and P. acuminatum when subjected to water-level oscillations. We hypothesized that (1) anatomic traits related to gas transfer and photosynthesis of P. ferrugineum and P. acuminatum change in response to water-level fluctuations and depth and that (2) P. acuminatum shows greater phenotypic plasticity than does P. ferrugineum to variations in water depth.…”

“…The rationale for hypothesis (1) is based on studies demonstrating that the anatomy and morphology of macrophytes adjust to changes in limnological conditions caused by water-level fluctuations (Cruz et al, 2019(Cruz et al, , 2020Sculthorpe, 1985). The rationale for hypothesis (2) was inspired in the fact that there is previous evidence that P. acuminatum has greater morphological plasticity than does P. ferrugineum (Murillo et al, 2019) because it is more subject to evolutionary pressures associated with floods.…”