Sodium uptake of Iris wilsonii and its photosynthetic responses to high-salinity stress in microcosm submerged beds.

In order to investigate the performance of Iris wilsonii in high-salinity wastewater, seven microcosm submerged beds were built with rectangular plastic tanks and packed with marble chips and sand. Each submerged bed was transplanted with six stems of I. wilsonii. The submerged beds were operated in a 7-d batch mode in a greenhouse with artificial wastewater for three 42-d periods. Influent to the seven submerged beds had different contents of NaCl, 0, 1, 2, 4, 6, 8, and 10% (by weight). The results suggested that lower salinity contents (1-2%) in influent or during short stress time (0-14d) did not inhibit net photosynthetic rate, stomatal conductance, and transpiration rate of I. wilsonii, and the chlorophyll of I. wilsonii was not damaged. When initial NaCl contents were at 4% and above, however, all photosynthetic parameters were significantly decreased. It was concluded that I. wilsonii could take up Na+ in wastewater, but higher salinity (4-10%) in wastewater would inhibit the growth of I. wilsonii.