2.3.3. Nitrogen, phosphorus content and water contentdetermination in plants
At the end of every two weeks in the pilot scale experiments,water spinach was carefully harvested and removed from the floating bed and gently washed with tap water. It was blotted with absorbing paper, and the fresh weights were measured. Then, it was dried at 80◦C for 48 h in oven, and the dry weights were recorded.
The concentrations of total nitrogen (TN) and total phosphorus (TP) in different organs (leaf, steam and root) of water spinach plants were measured according to standard methods (ISSCA,1980). Every sample was measured three times and the averagevalue was adopted.