Salt response of Crithmum maritimum, an oleagineous halophyte

Crithmum maritimum is a perennial Apiaceae growing naturally in rocky coasts. The oil extracted from its seeds seems to be convenient for human consumption. Physiological aspects of its salt response were studied in a laboratory with NaCl concentration ranging from 0 to 300 mM. The results show that C. maritimum is a facultative halophyte, since it does not require salt for maximal growth. Fifty percent reduction in shoot DW, leaf surface area and leaf number were observed at 150 mM NaCl, indicating that C. maritimum is moderately tolerant to NaCl. Culture in the presence of NaCl led to large accumulation of Na super(+) and Cl-in leaf tissues, without significant change in leaf water content. Thus, C. maritimum seemed to be able to sequester salt in leaf cells for osmotic adjustment. Indeed, the mean salt concentration in leaf tissue water was always higher than medium osmolarity. Growth was limited mainly by salt-induced decrease in the number of leaves. Biomass production per unit of leaf surface area was diminished only at highest salt concentrations. The presence of NaCl in the medium imposed a strong restriction in nutrient (K super(+) and Ca super(2+)) acquisition, which was due to inhibition of both root intrinsic performance for ion transport and root growth. In summary, salinity restricts C. maritimum growth through limitation of mineral nutrient acquisition, rather than osmotic and ionic deleterious effects.