The purification effect of three vegetables and different cultivation on aquaculture water from shrimp pond

Abstract:

In order to study the purification effect of three vegetables and cultivation on shrimp aquaculture water and identify a suitable vegetable and cultivation, the experiment was conducted to compare vegetables growth, absorptivity of nitrogen and phosphorus, water chemistry conditions with three vegetables (water fennel, water spinach, lettuce) with three cultivations planted in the shrimp aquaculture water. The results showed: the daily increase biomass per unit and the absorptivity of nitrogen and phosphorus by water spinach was significantly higher than water fennel and lettuce, and the survival rate of water spinach was highest too. All of the three plants had a purifying effect on the shrimp pond water, especially the water spinach. 20 days later, the contents of TAN, NO^-₃-N, TN, TP and COD_Mn of the water in spinach ponds decreased by 55.0%,78.6%,52.6%,44.2% and 41.3% respectively, secondly the water fennel. There was no significant influence on biomass increases and concentration of nitrogen and phosphorus for water fennel and water spinach under three floating cultivations. However, the growth condition of lettuce with floating board was the best in the lettuce group. The study showed environment adaptability of the water spinach to shrimp aquaculture water was the strongest in the three vegetables, so it was the best suitable for planting in shrimp ponds and the knot planting pattern was the best way to plant water spinach. In accordance with status of shrimp culture in Shanghai, it was suggested that half of the unutilized nitrogen in the culture period could be absorbed by planting the water spinach at 500 kg/hm2 in an early shrimp culture stage.