Efeitos do sombreamento na biomassa, reprodução e anatomia de Salvinia auriculata (Salviniaceae)

Abstract

Aquatic plants exhibit great plasticity to adapt to the environment. This plasticity is attached to the ability of the organism to change it physiology or morphology to respond the environment conditions variations. Plants that are in situation of limited resources can development strategies to go over stress. One of the essential resources to aquatic macrophytes is the light availability, especially for conducting photosynthesis and others metabolic processes. Salvinia auriculata is an aquatic fern know to be a weed plant with a fast growth. Its ramets can expand in a rampant way on the water surface and harm the environmental balance. Knowing the morphological changes under harsh conditions is important to understand the strategies that plant develops to growth and reproduction. The aim of this study was to observe the shading effects on biomass allocation, reproduction and leaf anatomy of S. auriculata to understand the changes that the plant presents under light limitation. The experiment was conducted on a greenhouse using shading nets to three treatments (0%, 35% and 70% of shading). The results show that the shaded condition decreased the ramets biomass and the sporocarps biomass, structures originated by sexual reproduction. The plant invested in asexual reproduction by buds production in shaded treatments. Moreover, there were changes in leaf anatomy with the reducing of tissues thickness attached to the photosynthesis. However, the leaf architecture was maintained and the ramets develop even in low light. It shows that S. auriculata presents reproduction and leaf anatomy plasticity that is capable to maintain the ramets development even in shaded conditions.