Plasticity in structural and functional traits associated with photosynthesis in Fimbristylis complanata (Retz.) Link. under salt stress

摘要

Fimbristylis complanata (Retz.) Link. is a halophytic sedge and commonly found in salt-affected wetlands and salt marshes. This species is less explored, particularly no information available on salinity tolerance in the literature. In the present work, structural and functional modifications of photosynthesis in F. complanata were evaluated under salt stress. A complete randomized design with three replications and three salt regimes (0, 200 and 400 mM NaCl) were maintained throughout the experiment. Population SH collected from the highest saline habitat (ECe 49.28 dS m-1 ) ranked as the highest tolerant, which showed an increase in biomass and chlorophyll pigments under salt stress. Modification in gas exchange parameters include decline in transpiration rate (E), while increase water use efficiency (WUE) and net CO2 assimilation rate (Pn), while structural modifications in SH population include increase in leaf succulence, cortical region thickness, bulliform thickness, aerenchyma formation, metaxylem and phloem area. Moderately saline population KM (ECe 29.56 dS m-1 ) exhibited significant alterations, like E (transiently up to 200 mM NaCl) and maintence of Pn up to 400 mM. This population altered leaf structural and epidermal traits related to photosynthetic efficiency. Least saline population LR (ECe 21.49 dS m-1 ) accumulates high chlorophyll content, increased leaf succulence and secured higher abaxial stomatal density. Present results suggest that F. complanata could proficiently maintain photosynthesis by several structural and functional modifications.