The floating bed used was different from other traditional floating beds. The material that was chosen to construct the floating bed was bamboo, which is environmental friendly. The length and width of bamboo raft were 3–3.5 m and 1–1.2 m, respectively. A small PVC tube (32 mm × 40 mm) was roped every 15–20 cm on bamboo raft, through holes of which the roots of plants could elongate into water. These tubes were fixed by tieline buckle. 4–5 individual plants of water spinach were put into each PVC tube, and then the settled bamboo raft was kept into selected river, which was shown in Fig. 1(a).