5种浮床植物对宁夏引黄灌区稻田退水中氮磷的去除效果

为了探索植物浮床技术应用和农业面源污染防治的有效措施，采用稻田退水沟渠原位实验，研究了美人蕉(Canna indica)、千屈菜(Lythrum salicaria)、黄菖蒲(Iris pseudacorus)、空心菜(Ipomoea aquatica)、水稻(Oryza sativa)5种不同浮床植物对退水中氮、磷的去除效果。结果表明，在稻田退水中生长4个月后，5种浮床植物生物量均大幅度增加。其中，美人蕉生物增长量最大，为97.2 g·株⁻¹，其次为千屈菜达到81.3 g·株⁻¹；空心菜成活率最高，达到91.67%，美人蕉其次，为87.50%，而水稻成活率最低，仅为60.71%；千屈菜茎叶和根系的氮含量最高，分别达到0.85%和0.65%；美人蕉茎叶、根系的磷含量最高，分别达到0.15%、0.17%；空心菜氮吸收量最高，达到14 239.46 mg·m⁻²，美人蕉其次，为10 798.00 mg·m⁻²；水稻磷吸收量最高，达到407.11 mg·m⁻²，空心菜其次，为374.41 mg·m⁻²；空心菜对稻田退水中总氮(TN)去除率最高，达到85.88%，其次为美人蕉，为81.67%；空心菜总磷(TP)去除率最高，达到80.32%，其次为水稻，达到72.86%。根据上述实验结果，推荐浮床空心菜和美人蕉作为宁夏引黄灌区农田排水沟水质改善的主要植物。

Removal effect of nitrogen and phosphorus in the return flow of rice paddy in Ningxia yellow river irrigation region by five plants cultivated on floating-bed

In order to investigate the application of the floating bed and explore the effective measures for agricultural non-point source pollution control, five kinds of local plants (Canna indica, Lythrum salicaria, Iris pseudacorus, Ipomoea aquatica and Oryza sativa) were cultivated on the floating-bed in the return flow ditches of rice paddy to compare their removal effects of nitrogen and phosphorus. The results showed that the biomass of the five kinds of floating bed plants increased significantly in the return flow of rice paddy for four months cultivation. The biomass growth of Canna indica was the largest, which was 97.2 g·plant−1, and it was followed by Lythrum salicaria with 81.3 g·plant−1. The survival rate of Ipomoea aquatica was the highest with a value of 91.67%, and it was followed by Canna indica with 87.50%, while the survival rate of Oryza sativa was the lowest with a value of only 60.71%. The total nitrogen concentrations in stems/leaves and roots of Lythrum salicaria were the highest, which were 0.85% and 0.65%, respectively. The total phosphorus concentrations in stems/leaves and roots of Canna indica were the highest, which were 0.15% and 0.17%, respectively. The largest nitrogen uptake amount occurred in Ipomoea aquatica with a value of 14 239.46 mg·m−2, which was followed by Canna indica with 10 798.00 mg·m−2. The largest phosphorus uptake amount occurred in Oryza sativa with a value of 407.11 mg·m−2, which was followed by Ipomoea aquatica with 374.41 mg·m−2. The total nitrogen (TN) removal efficiency in the return flow of rice paddy by Ipomoea aquatica was the highest with a value of 85.88%, which was followed by Canna indica with 81.67%. The total phosphorus (TP) removal efficiency in the return flow of rice paddy by Ipomoea aquatica was the highest with a value of 80.32%, which was followed by Oryza sativa with 72.86%. Therefore, Ipomoea aquatica and Canna indica cultivated on floating-bed were recommended as the main plants for improving the water quality of farmland drainage ditch in Ningxia yellow river irrigation region.