Salinity and phosphorus availability differentially affect plant growth, leaf morphology, water relations, solutes accumulation and antioxidant capacity in Aeluropus littoralis

Abstract

In this study, we examined the combined effect of moderate salinity (100 mM NaCl) and three phosphorus (P) levels: low, moderate and high (5 µM, 60 µM and 180 µM KH2PO4, respectively) on several physiological parameters in the facultative halophyte Aeluropus littoralis. Our results showed that plants cultivated under low P availability exhibited higher leaf hair and trichome densities, root length, and shoot soluble sugars concentrations. The response of plants to combined salinity and P deficiency was similar to that of plants cultivated under P deficiency only. Furthermore, in the absence of salt, A. littoralis plants reached maximum biomass at 180 µMP. However, in the presence of 100 mM NaCl, plants exhibited maximum growth from 60 µMP which suggests that salt supply decreased P requirements of A. littoralis plants. Moreover, salinity has no significant effect on biomass production, shoot water content and shoot potassium (K+) content when combined with 5 µMP and it significantly decreased gradually these parameters when combined with 60 µMP and 180 µMP. This was associated with higher values of P and K use efficiencies, leaf hair and trichome densities, total polyphenol content, and total antioxidant capacity in plants cultivated under combined effects of salinity and P deficiency.