Ramet versus sporocarp production in the aquatic fern Salvinia auriculata (Salviniaceae): the role of shading

Abstract

Aquatic plants exposed to environmental changes exhibit plastic responses, resulting in functional adjustments to reduce stress effects. Lack of light can limit plant development and can affect biomass allocation and reproduction, stressing plants and sometimes halting their growth. Shading techniques have been used to control the excessive growth of weed plants, such as the aquatic fern Salvinia auriculata Aublet that can form dense mats on the water surface, causing problems in water use. We used shading nets in a greenhouse experiment to evaluate the effect of shade on the biomass of S. auriculata, and to determine if the fern changes its allocation of biomass to sexual (sporocarps) or asexual (buds) reproduction under different shade levels (full-sun control, 35% shade, and 70% shade). Under shade conditions, ramet biomass decreased and no sporocarps were produced, although the number of buds increased. Production of structures for sexual reproduction incurs a high energy cost, so S. auriculata invested in bud production (clonal reproduction). The differing energy requirements resulted in a significant trade-off between bud and sporocarp production. In conclusion, our study indicated that shading is not an efficient control technique for S. auriculata since it did not affect the clonal reproduction, a strategy that accelerates colonisation and facilitates rapid spread.

Self-shading effect in the growth, photosynthesis and anatomy of Typha domingensis Pers.

“…It is important to note that the shading effect on aquatic plants is poorly understood and no information can be found for cattail species. For the fluctuant macrophyte Salvinia auriculata Aubl., shading did not affect the clonal growth and stimulated the production of reproductive structures (Medeiros et al 2018). It is reasonable that, despite competition effects, T. domingensis individuals from a HDP condition can promote a self-shading effect by creating a microclimate with reduced radiation intensity and that this modification may have consequences to plant ecophysiology, anatomy and growth.…”

Sex allocation in aquatic ferns: The role of body size

“…Due to this plasticity, trade-offs between different organs and functions have been reported in several aquatic plants (Coelho, Deboni, & Lopes, 2005a;Demetrio, Barbosa, & Coelho, 2014;Li, Barrett, Song, & Chen, 2019;Thompson & Eckert, 2004). Among the species of aquatic ferns belonging to the family Salviniaceae, the species Salvinia auriculata exhibits great morphological plasticity under densely crowded conditions (Coelho, Lopes, & Sperber, 2000) and under shade conditions (Julien, Center, & Tipping, 2002;Julien, Hill, & Tipping, 2009;Room, 1994), and exhibits a trade-off between bud and sori production (Medeiros et al, 2018). Salvinia species are considered aquatic weeds due to their fast clonal growth, which can result in rapid expansion on the water surface associated with negative impacts in aquatic environments, (Room, 1994;Julien, Center, & Tipping, 2002;Julien et al, 2009).…”

Morphological and allometric variation due to percentage of cover in Eichhornia azurea (Swart) Kunth (Pontederiaceae)

“…Thus, intraspecific trait variation may be the main factor underlying the species capacity to colonize new environments, resist environmental changes and respond to intraspecific competition (Lankau 2011;Silva et al 2019). Aquatic plants, for instance, may modify their morphology, presenting an adaptive capacity allowing for higher population survival rates (Coelho et al 2005;Medeiros et al 2018). Additionally, they have morphological functional traits that assist them in adapting to environmental variation and their successful colonization in aquatic environments is in part due to their life history plasticity (Catian et al 2018).…”