Photosynthetic response of the floating-leaved macrophyteNymphoides peltatato a temporary terrestrial habitat and its implications for ecological recovery of Lakeside zones

Abstract

Key-words: Nymphoides peltata, gas exchange, water-use efficiency, acclimation, lakeside zone restorationFor the ecological recovery of lakeside zones in shallow eutrophic lakes, choosing suitable aquatic macrophytes which could adapt to the temporary terrestrial habitat due to water level change is very important. In the present study, an experimental approach was carried out to explore the photosynthetic response of the typical floating-leaved aquatic plant Nymphoides peltata (N. peltata) to varying environmental factors. N. peltata grown under aquatic and terrestrial habitats showed similar photosynthesis-irradiance response patterns. The investigation of diurnal changes in gas exchange revealed that the net photosynthetic rate (P N ) and water-use efficiency (WUE) of the N. peltata grown in the terrestrial habitat were 68% and 94% higher, respectively, than those in the aquatic habitat at nine in the morning. N. peltata grown in the terrestrial habitat had approximately 51% less stomatal density and a 77% smaller stomatal aperture area compared with those grown in aquatic habitats. The above results indicated that N. peltata could be well-acclimated to the terrestrial habitat by developing a series of photosynthetic acclimation features. Our study may provide an important reference for restoration in lakeside zones of shallow eutrophic lakes. RÉSUMÉRéponse photosynthétique d'un macrophyte à feuilles flottantes Nymphoides peltata à un habitat terrestre temporaire et ses implications pour la restauration écologique de zones littorales lacustres Mots-clés :Pour la restauration écologique de la zone littorale dans les lacs eutrophes peu profonds, le choix des macrophytes aquatiques appropriés qui pourraient s'adapter à l'habitat terrestre temporaire dû aux changements du niveau de l'eau est très important. Dans la présente étude, une approche expérimentale a été menée pour étudier la réponse photosynthétique d'une plante aquatique à feuilles flottantes typique Nymphoides peltata (N. peltata) à des facteurs environnementaux changeants. Des N. peltata cultivés dans des habitats aquatiques et terrestres ont montré des schémas « photosynthèse-éclairement » de réponse similaires. L'étude des variations diurnes des échanges gazeux a révélé que le taux de photosynthèse (EUE) des N. peltata cultivés dans l'habitat terrestre étaient de 68 % et 94 % plus élevés, respectivement, que ceux de l'habitat aquatique à neuf heures du matin. N. peltata cultivés dans l'habitat terrestre avaient une densité stomatique environ 51 % inférieure et une surface d'ouverture des stomates inférieure de 77 % par rapport à ceux qui sont cultivés dans les habitats aquatiques. Les résultats ci-dessus montrent que N. peltata pourrait être bien acclimaté à l'habitat terrestre en développant une série de caractéristiques d'acclimatation photosynthétiques. Notre étude pourrait fournir une référence importante pour la restauration dans la zone littorale de lacs eutrophes peu profonds.

Using White Star (Nymphoides humboldtiana) for lake landscaping

“…When plants were grown under 30 cm water depth, the leaves showed more than twice the leaf area of those cultivated under water saturation conditions, and in this case, when submitted to low luminosity, a higher reduction in leaf area was noticed (Figure 1). In N. peltata, the authors noticed physiological adaption to water level variation, which may suggest different behavior for this species (Yu et al, 2014). This biomass accumulation of White Star in a high luminosity environment and high water depth favored floral exuberance, since no flowering or minimum flowering was noticed, when the plant was grown in a shaded place under low water depth.…”

Plant traits and environment: floating leaf blade production and turnover of Nymphoides peltata (S.G. Gmel.) O. Kuntze (Menyanthaceae)

“…Floating leaves with their petioles contribute most to the biomass production of N. peltata ( Brock et al, 1983a ). Floating leaf blades are important for the plant by processes such as photosynthesis ( Smits et al, 1988 ; Yu et al, 2014 ), gas ventilation ( Grosse & Mevischutz, 1987 ; Grosse & Bauch, 1991 ), chemical accumulation ( e.g ., heavy metals by hydropotes ( Brock, 1983 ; Lavid et al, 2001 )) and suppression of other aquatic macrophytes by shadowing ( Larson, 2007 ; Zhu et al, 2019 ). Furthermore, floating leaf blades function as substratum for particular organisms (periphyton, sessile animal eggs), free moving species at and near the water surface, as isles in the open water for air-breathing animals, as substratum and nutrient for fungi and microbes and as food for more or less specialized invertebrates and for vertebrates.…”

“…The seedlings can quickly grow towards full grown plants ( Brock, Van der Velde & Van de Steeg, 1987 ). The plant also adapts easily to a terrestrial way of life ( Li et al, 2010a ; Li, Yu & Xu, 2010b ; Yu et al, 2014 ) and can even be cultured as a pot plant ( Heimans & Thijsse, 1956 ). Emergent leaves show a longer life span than floating leaves ( Tsuchiya, 1988 ).…”