Differences in Nitrogen and Phosphorus Removal under Different Temperatures in Oenanthe javanica Cultivars

Plant selection plays a critical role in phytoremediation. However, previous research has focused on comparing different plant species but has ignored different cultivars. Here, a laboratory experiment was performed to analyze the nitrogen (N) and phosphorus (P) removal performance of different cultivars of Oenanthe javanica, which are widely employed for phytoremediation in China. Seven cultivars were planted on simulated livestock wastewater with high N and P content prepared with compounds for 22 days in two artificial climate chambers with different temperatures. N and P contents were monitored to estimate the nutrient removal performance of the cultivars. ‘Suzhou Yuanye’ had the highest N removal ability at room temperature (45.33 ± 1.92%) and under cold stress (39.63 ± 2.15%) in 22 days, and it could also remove P effectively (99.32 ± 0.33% at room temperature and 77.50 ± 0.08% under cold stress). ‘Yixing Yuanye’ performed the best in P removal (97.90 ± 2.89% at room temperature and 99.57 ± 0.61% under cold stress). ‘Liyang Baiqin’ performed well in N removal only at room temperature (44.30 ± 1.03%). ‘Suqian Jianye’ had low removal efficiencies for both N and P. From the biomass and N content, we could conclude that the high N removal efficiency of ‘Suzhou Yuanye’ is due to high N assimilation of the plant. However, ‘Yixing Yuanye’ did not show higher P assimilation ability than other cultivars. Taken together, the selection of cultivars is important for phytoremediation projects using O. javanica, and ‘Suzhou Yuanye’ is much more suitable for phytoremediation than other cultivars.