[The effects of fertilization on yield and root diameter of Codonopsis pilosula var. modesla].

Field trials were conducted using three factors regression design of quadratic orthogonal rotation. The result indicated that under the condition of cultivation, yield and average root diameter of Codonopsis Pilosula var. modesla (Nannf) L.T. Shen showed a positive correlation with N fertilizer application on high fertilization level; The effect of major three fertilizer on yield and average diameter of root was K > P > N. In the course of selective optimization yield which is higher than 3750 kg/hm2 (fresh weight) and average diameter of root which is more than 1.5 cm, the index of fertilizer application for N, P and K pure nutrient is 155 kg/hm2, 250 kg/hm2 (P2O5) and 60 kg/hm2 (K2O) respectively. The ration of N:P:K is 1:1.6:0.4.