Variation of sodium uptake rate in Suaeda glauca (Bunge) and its relation to plant size and salt acclimation

To characterize the pattern of sodium uptake by Suaeda glauca (Bunge) plants at mild salinity, this study investigated the temporal variation of sodium uptake rate (mmol Na+ plant(-1) d(-1)) and its relation to plant size (i.e., main stem length) and salt acclimation for S. glauca grown in nutrient solutions with 6, 8, or 10 mM NaCl. During the 23-d salt treatment, sodium uptake rate in S. glauca increased gradually at 5-to 7-d intervals with time advancement and showed a positive exponential relationship with the development of plant size. During the first week (0-7 d) of salt treatment, the weekly average sodium uptake rate was higher in larger plants than in smaller ones. During the last week (18-23 d) of salt treatment, non-salt-acclimated plants showed a similar sodium uptake rate (on a weekly average) to salt-acclimated plants when their plant sizes were not significantly different. These results suggest that at the largest plant size (i.e., 1 wk before harvesting as a leafy vegetable), S. glauca reached the maximum level of sodium uptake rate, which was affected to a larger degree by plant size than by salt acclimation on a weekly scale.