Altered water relations, selective nutrient uptake, and reduced Na+ flux make Halopeplis perfoliata an obligate halophyte

Abstract

Halopeplis perfoliata, a succulent halophyte of coastal marshy habitats, was grown in a greenhouse to study its adaptive responses in terms of growth, osmoregulation, and N-metabolism following one-month exposure to salinity (0, 150, 300, and 600 mmol $L^{–1}$ NaCl). Biomass was optimal in 150 mmol $L^{–1}$ NaCl with unaltered malondialdehyde (MDA) levels. On the other hand, biomass remained comparable to non-saline control with some increase in MDA in 300 and 600 mmol $L^{–1}$ NaCl. Osmotic potential $(ψ_S)$ was maintained up to 300 mmol $L^{–1}$ NaCl that correlated with an increase in succulence (SC) and lower water deficit (WD), whereas sap $ψ_S$ was lowest in 600 mmol $L^{–1}$ NaCl along with lower SC and high WD. Sodium level gradually increased in shoot and was higher than the root. Potassium deficiency was not observed up to high salinity. Both soluble sugars and nitrogen isotope $(δ^{15}N)$ increased transiently in 300 mmol $L^{–1}$ NaCl. Hence, modulations in water relation, selective nutrient uptake, and controlled $Na^{+}$ flux appear important for salinity tolerance of H. perfoliata.