Optimization of nutritional ration for Ipomoea aquatica Forsk growth based on the water quality of Yinchuan plain

The comprehensive effects of NO-3-N,P,K and Ca concentrations on growth of Ipomoea aquatica Forsk were studied by means of quadratic general rotational design under Deep Flow Technique(DFT) culture in energy saving greenhouse.The results calculated from regression equation between yield and the four element concentrations showed that the contribution to yield of Ipomoea aquatica Forsk was in the order of nitric-N(NO-3-N)potassium(K)phosphorus(P)calcium(Ca).The interaction effect on yield between N and K was found significant which appeared in a positive correlation at lower level concentration and in a negative correlation at higher level concentration.The optimal ration of N,P,K and Ca for highest yield of individual Ipomoea aquatica Forsk(108.81 g) was calculated by computer to be 9.0,0.5,4.5 and 4.0 mmol/L,respectively.The verification experiment showed that the growth,root vigor,yield,nutrient content and quality of Ipomoea aquatica Forsk in the optimized nutrient ration were all excelled those of the control.