Research On The Application Of Several Hydroponic Vegetables In The Shrimp Ponds

The accumulation of nitrogen, phosphorus, and other nutrients would be bound tolead to deterioration of water environment in shrimp ponds, causing the shrimpdisease-prone, and how to control the aquaculture water environment has become animportant part in the process of Litopenaeus vannamei farming. The purification effectsof aquatic vegetables on the water quality in shrimp ponds were researched. Accordingto screening the vegetable of fast growth rate and the strong purifying capacity andquantitative understanding the purification effects of preferably hydroponic vegetableson the water quality in shrimp ponds, the preferably hydroponic vegetables was plantedby a certain area in Litopenaeus vannamei scale aquaculture ponds. So, the shrimp-dishsymbiotic ecological farming model of stable water quality was established, which willprovide the scientific basis for the building of shrimp-dish symbiotic ecological farmingmodel, carrying out the ecological farming of shrimp, and improving the economicefficiency of shrimp farming. The main content is divided into the following four parts:1. Study on the screening of vegetable varieties and the planting way in shrimppondsIn order to research the purification effect of three vegetables (Ipomoea aquatica,Lactuca sativa, and Brassica Oleracea L.var acephala DC) and cultivation on shrimpaquaculture water and identify a suitable vegetable and cultivation，the experiment wasconducted in three indoor shrimp ponds to compare vegetables growth，absorptivity ofnitrogen and phosphorus，water chemistry conditions with three vegetables with threecultivations planted in the shrimp aquaculture water．The results showed that thepurification effect of Ipomoea aquatica on water quality in shrimp ponds was higherthan other vegetables. The removal rate of NO2--N by Ipomoea aquatica was1.3and1.9times of Lactuca sativa and Brassica Oleracea L.var acephala DC, respectively,and the removal rate of TAN by Ipomoea aquatica was higher15.6%and6.2%than Lactuca sativa and Brassica Oleracea L.var acephala DC, respectively. In addition, theabsorptivity of nitrogen and phosphorus by Ipomoea aquatica was significantly higherthan the other two vegetables with three planting ways (P<0.05), which was particularlyprominent knot type. and the absorptivity of nitrogen was10.8and5.4times of Lactucasativa and Brassica Oleracea L.var acephala DC, respectively. Additional, environmentadaptability of the Ipomoea aquatica to shrimp aquaculture water was the strongest inthe three vegetables, and the survival rates of Ipomoea aquatica were as high as100.0percent, so it was the best suitable for planting in shrimp ponds and the knot plantingpattern was the best way to plant water spinach.2. Study on the purification effect of Ipomoea aquatica on shrimp aquaculturewater with different acreageIn this study, the purification effect of Ipomoea aquatica on shrimp aquaculturewater with different acreage was researched by analyzing the water quality and thegrowth of vegetables in ponds during the experiments. The Ipomoea aquatica wasplanted at1.25kg/m2in shrimp ponds and the cultivated area were0%,5%,10%,15%,20%, and30%, respectively. The results showed that during the experiment, the sizeorder of absorptivity of nitrogen and phosphorus by Ipomoea aquatica was as following:10%﹥30%﹥20%﹥15%﹥5%and10%﹥15%﹥20%﹥5%﹥30%, respectively. Inaddtion, the removal rate of TAN, NO2--N, NO3--N, TN, TP, and CODMnconcentrationin the shrimp ponds and the daily increase biomass per unit of Ipomoea aquatica (15.78kg/m2) at the acreage of10%were higher than other treatment, so it was the bestplanting area.3. Study on the change of water quality in different regions and diurnal variation ofwater quality in shrimp ponds planted Ipomoea aquaticaIn this study, the change of water quality in different regions and diurnal variationof water quality in shrimp ponds planted Ipomoea aquatica were researched bymonitoring the change of water quality and nitrogen and phosphorus content ofsediments in vegetable area, the nearshore area, and the central area of planting pondsand the water quality24h day and night surveillance in shrimp ponds. The resultsshowed that the TAN (1.28±0.32mg/L) and TN (6.72±2.32mg/L) average content inthe vegetable area was lower10.49%and4.27%than the nearshore area, respectively,the CODMnaverage content was significantly higher than the central area, and theremaining water quality parameters content were not significantly at different among regions. In addition, the TN, TC, and TP content of sediments in vegetable area wereslightly lower than other area. The experiments of24h day and night monitoring waterquality in shrimp ponds showed that: the TAN、TN、TP、PO43--P, and CODMncontent inplanting ponds were significantly lower than the control ponds (p<0.05), and the DOconcentration was kept over5mg/L.4. Study on the purification effect of Ipomoea aquatica on Litopenaeus VannameipondsIn this study, the purification effect of Ipomoea aquatica on Litopenaeus Vannameiponds was demonstrated in shrimp ponds planted Ipomoea aquatica at the area of10%from June to October on2012and from August to October on2013. The results showedthat the NO3--N, PO43--P, and CODMnconcentration in planting ponds in2012and theTAN, TN, TP, PO43--P, and CODMnin the planting ponds in2013were lower than thecontrol ponds (p<0.05), respectively. The percentage removal of total nitrogen (TN) andtotal phosphorus (TP) in the planting ponds and in the control ponds were38.50%and22.03%,34.82%and19.02%, respectively. The feed conversion rate was higher in theplanting pond than the control pond (p<0.05) and the fresh weight of Ipomoea aquaticawas2441±183kg and the removal rate of TN and TP was6.23%and3.9%,respectively. The average product of shrimp in the shrimp ponds planting Ipomoeaaquatica (treatment group, two ponds) was4768.75±111.69kg/hm2, which was higherthan the control ponds without planting Ipomoea aquatica4120.46±90.00kg/hm2(p<0.05). The results suggested that the aquaponic farming model could improve thewater quality effectively and the economic benefits of shrimp farming, so a highershrimp density could be stocked in the aquaponic system.