Effects of Temperature and Phosphorus Concentration on Nitrogen and Phosphorus Uptake of Azolla imbricata

The growth status of Azolla imbricata under different temperature and phosphorus concentrations was simulated and studied, so as to understand the growth rule of A. imbricata biomass and the optimal temperature and optimal phosphorus concentration for phosphorus absorption in the water. The results showed that A. imbricata can grow well under 10 - 30 ℃, with optimal temperature of 20 - 25 ℃. The tissue phosphorus and nitrogen contents of A. imbricata and their relative growth rates increased with the increase of phosphorus concentration in water, with the tissue phosphorus content reaching highest under the water temperature of 25 ℃. This indicates that A. imbricata is a good aquatic plant to remove phosphorus in the water, but the absorption can be affected by interaction of water temperature and phosphorus concentration in the water. The phosphorus absorption increases with the increase of water temperature and phosphorus concentration in the water, although the absorption rate has the trend of decreasing. The optimal phosphorus absorption by A. imbricata can be achieved under the water temperature of 25 ℃ and phosphorus concentration of 0.075 mg/L.