Effects Of N-P-K On The Growth, Yield And Quality Of Radish

The effects of N, P, K concentration on the growth, yield and quality of radish (Raphanus sativus L.) were studied by means of soilless culture in this paper. The research includes two parts: hydroponical culture and substrate culture. The effects of four different concentration of N, P, K respectively on the growth and development of radish were researched through hydroponical culture experiment. The effects of combined N, P, K on the yield and quality of radish were investigated by substrate culture experiment, corresponding regression mathematical models were estabished, and effects and interactions of the three fertilizer factors were analysed respectively. The growth and development of radish in the whole growth period were also studied in the experiment.The results of hydroponical culture are as follows:1. With the rising of N concentration, the chlorophyl content was increased significantly, while which was not significantly affected by the rising of P, K concentration.2. The R/T of radish was closely associated with N, P, K concentration. The R/T was high with the deficiency of N, P, K rexpectively. And with the existence of N, P, K, the R/T was decreased by the rising of N concentration and decreased too by the high or low concentration of P, K.3. When N, P were deficient, the area, flesh and dry weight of the leaf and flesh and dry weight of the root were all significantly smaller than that of N, P were supplied; the leaf area and flesh weight of K defficeiency were significantly lower than that of K was supplied, while the leaf dry weight was not influenced by K concentration.4. When N, P, K were supplied, the leaf area, flesh and dry weight of leaf were increased with the rising of N concentration, but which were not affected by P, K concentration. And the high or low concentration of the N, P, K had the negative effects on flesh and dry weight of the root, all of them influenced the development of the roots.The results of substrate culture are as follows:5. The economic yield of radish increased by suitable combination of N, P, K concentration and decreased by the high or low concentration of the three factors. And N is the major factor influencing the yield, next is P, the smallest is K.6. The quality of radish was improved by suitable combination of N, P, K concentration and was decreased by the high or low concentration of N, P, K. The contribution degree of the three factors on soluble sugar content and protein content of radish was N>K>P, and with regard to vitamin C content the order of contribution degree was K>P>N.7. On the basis of mathematical models between N, P, K and yield, nitrate content, soluble sugar content, protein content as well as vitamin C content, applying the method of probability analysis, and through synthetical optimizing the optimum combination of N, P, K for substrate culture of radish was obtained, which was N =25.16mmol/L, P=1.50 mmol/L, K=8.10 mmol/L. the proportion of the three factors is N: P2O5: K2O=1: 0.47: 1.08.8. The growth parameters RGR and NAR had positive correlation with the yield of radish, while LAR had negative correlation with it. The correlation between every growth parameter and yield was strong in the early growth period, and which is weak in the later growth period.