[Study on economic NPK(nitrogen-phosphorus-potassium)-requirements for medicinal safflower]

A design of second order orthogonal rotative regression was developed and field tested, and a model for obtaining 18kg/mu dry flower yield was simulated and built according to several better combinations based on the model of total safflower dry flower yield. The optimal NPK-requirements for obtaining the above 18kg/mu dry flower yield are N:6-6.5kg/mu, P2O5:10.0-11.0kg/mu, K2O:6.9-10.0kg/mu. These requirements may be adjusted rationally according to soil fertility, manure sources, and so on.