| Its first step was studied with the simplex centroid design the effects in the combination of nitrogen phosphorus and potassium fertilizer on yield of the Znathoxylum Bungeananum.According to the data obtained,a mathematical model was established,in which N、 P、 K were variables,the skin and seed of the Z.Bungeananum were dependent variables.The data reduction analysis showed that the effect of fertilizer combination is that high K and low P and low N |