Effects of Different Ammonia Nitrogen Concentrations on the Growth Characters of Ipomea aquatica

[Objective] The study aimed to discuss the influence of various ammonia nitrogen concentrations on the growth characters of Ipomea aquatica.[Method] Seven groups of hydroponics nutrient solutions with different ammonia nitrogen concentrations(0,0.1,0.5,1.0,5.0,10.0,50.0 mg / L) were made up to cultivate the cuttings of Ipomea aquatica,which was identified to be a suitable vegetable crop for water culture.The responses of the plant growth and the nutrient adsorption efficiency were studied.[Result] Nitrogen deficiency caused stunting of the plant growth,chlorosis of old leaves,and inhibition of tiller.When the concentration of ammonia nitrogen exceeded 0.5 mg / L,the plant grew rapidly.As the concentration was higher than 10.0 mg / L,the plant growth was inhibited,and the roots rotted,while the leaves fell off.The most suitable concentration of ammonia nitrogen for the plant growth was 1.0 mg / L,when the growth parameters were the optimum and the purification efficiency of ammonia nitrogen reached the maximum,namely 96.3%.When the concentration exceeded 1.0 mg / L,the roots became shorter and lighter,but the fresh weight of stems and leaves increased obviously.Moreover,the total biomass was greater than that of the treatments with lower concentrations of ammonia nitrogen than 1.0 mg / L.However,the purification efficiency had an inverse correlation with ammonia nitrogen concentration.[Conclusion]The research could provide theoretical references for the popularization and application of ecological breeding model of fish,shrimp and vegetables.