Effects of water and fertilizers on tomato soluble sugar contents under alternate partial root-zone irrigation

【Objective】 The effects of irrigation and fertilizer amounts on soluble sugar contents of tomato were investigated under alternate partial root-zone irrigation.【Method】 Using a quadratic orthogonal regressive rotation design with five factors,the effects of irrigation water amount and fertilizer amounts including nitrogen,phosphorus,potassium and manure on soluble sugar contents of tomato were investigated by pot experiment under alternate partial root-zone irrigation.A regression model on water and fertilizer amounts and soluble sugar contents of tomato was established.Single and coupling effects of all five experimental factors were analyzed.【Result】 For the soil and tomato variety used in the experiment,the relationship between soluble sugar contents and K fertilizer amounts could be estimated as a second-degree parabola with open side down when other factors were at intermediate levels.Soluble sugar contents increased linearly with irrigation,P fertilizer and manure amounts,but were not affected by N fertilizer amounts.The interactions between the fertilizer amounts of N,P or K,between K and manure showed negative effects while the interactions between N fertilizer and manure amounts and between P and K fertilizer amounts were positive.【Conclusion】 The results suggested that irrigation amount and fertilizer amounts of N,P,K and manure significantly influenced soluble sugar contents in tomato through single factor or their interactions.Under the condition of alternate partial root-zone irrigation,increasing the amount of irrigation in a proper way,application of N and manure,K and P,and a high level of manure and a small amount of K can significantly improve soluble sugar contents in tomato.