Abstract: Using a pot experiment and quadratic orthogonal regressive rotation design with five factors，the effects of irrigation amount and fertilizer rates of nitrogen，phosphorus，potassium and manure on lycopene content in tomato were investigated. A model of regression relationship between water and fertilizer amounts and lycopene content in tomato was established. Single and coupling effects of all five experimental factors were studied. The results showed that for the soil and tomato variety used in the experiment，if other factors were zero codes，the relationship between lycopene content and irrigation amount，P fertilizer or manure rates could be estimated with a second-degree parabola，which was open downward，while the second-degree parabola between lycopene content and N or K fertilizer rates was open upward. Significant interactions occurred between the rates of P and K，P and manure，or K and manure，and certain interactions occurred between N and K，or N and manure，but no interaction between irrigation amount and any other experimental factors. It was indicated that large irrigation，or overuse of P fertilizer and manure did not benefit the lycopene content，and reasonable supply of N and K fertilizers could enhance the lycopene content in tomato effectively.

Key words: tomato, lycopene content, irrigation amount, nitrogen, phosphorus, potassium, manure, quadratic orthogonal regressive rotation design with five factors