Differences in growth rate and salt tolerance between varieties of the halophyte Centaurium littorale (Turner) Gilmour, and their ecological significance

Four varieties of Centaurium littorale were cultured on Hoagland’s nutrient solution with and without extra NaCl. The varieties investigated were var. littorale. var. iberoides (two biotypes), and var. latifolium from The Netherlands, and var. minus from England. The experimental plants were vegetative rosettes. The increase in fresh weight, the shoot:root ratio, the dry matter content, and the mineral composition of the leaves were determined. There appear to be infraspecific differences in growth rate. These agree with maximal plant size in the field. The growth rate in C. littorale is determined by the shoot:root ratio, the dry matter content of the leaves, but also by the leaf morphology. The physiological properties of the varieties investigated were affected in the salt treatments. Growth was reduced by a suction tension of 3.51 atm NaCI. The disturbance of the ionic balance by the accumulation of NaCl is a major factor in this growth reduction. Var. latifolium seems to have a low salt tolerance, which is in agreement with its occurrence on almost desalinized salt marshes.