Effect of salinity on the vegetative characteristics, biomass and chemical content of red mangrove seedlings in the south of Iran

We selected six months old seedlings of Rhizophora mucronata (Lam.) to evaluate the effect of different salinity on seedling growth, biomass and ion content in roots and leaves. We planted red mangrove propagules in plastic pots and irrigated them with freshwater (control), low salinity (EC: 8500 μm.cm; 25% sea water+75% freshwater), moderate salinity (EC: 29000 μm.cm; 50% sea water+50% freshwater) and high salinity (EC: 57000 μm.cm; 100% sea water) for six months. Seedling grown at moderate salinity, had higher leaf number, collar diameter, height, root length, root dry weight, total dry mass weight and leaf area relative to seedlings grown at lower or higher concentrations. Concentrations of sodium and chloride ions in both leaves and roots increased with increasing salinity. Calcium, potassium and nitrogen in both leaves and roots were highest in the moderate treatment, followed by control, low salinity and high salinity treatments. All ions were higher in leaves, except for calcium, which was higher in roots. It can be concluded that the moderate salinity levels as it balances seedling quality with reduced demand for freshwater.