Salt tolerance in the halophyte Suaeda maritima (L.) Dum. The influence of the salinity of the culture solution on leaf starch and phosphate content

The starch concentration in mature leaves of the halophyte Suaeda maritima increased from 4.7 to 7.3 mg mg-1 chlorophyll when sodium chloride (680 mol M-3) was added to the solution in which the plants were grown. This effect of salinity on the starch: chlorophyll ratio was greater in young than in old leaves. Electron micrographs showed the starch to be in the chloroplasts and this was confirmed by measurements on isolated chloroplasts. Total phosphorus concentration (mg mg-1 chlorophyll) in leaves of all ages from plants of S. maritima decreased on salinization of the growth medium suggesting an inverse relationship between phosphorus and starch concentrations. However, although leaf starch concentration varied with leaf age, phosphorus concentration did not. The cause of starch accumulation in chloroplasts at salinities which are optimal for growth (340 mol m-3) remains unclear.