Adopted twice saturated reqression and D-optimal design to stady the effect of nutrient N,P and K on cucumber yield by directly supplying solid N、P and K fertilizer(mixture of.organic and inorganic fertilizers) in eco-organic type soilless culture system.The maths models between fertilization rate and yield was established.The results indicated that N,P and K nutrient had significant effect on cucumber early yield.The optimum fertilization rate of of N,P and K were 0.83(unit:g/plant/time,the same as follows...