Tomato yield, quality and water use efficiency under different drip fertigation strategies

The advantage of alternate partial root-zone drip irrigation combined with ratio of basal N fertilizer to topdressing N fertilizer via drip fertigation on tomato yield, quality and water use remains unresolved. This study has investigated the influences of three drip irrigation methods, including conventional drip irrigation (CDI), alternate partial root-zone drip irrigation (ADI), and fixed partial root-zone drip irrigation (FDI), and five N treatments (N0-100: 100% of N fertilizers as topdressing, N10-90: 10% as basal fertilizer and 90% as topdressing, N20-80: 20% as basal fertilizer and 80% as topdressing, N30-70: 30% as basal fertilizer and 70% as topdressing, and N40-60: 40% as basal fertilizer and 60% as topdressing. All treatments received the same N rate) on tomato yield, quality and water use efficiency, and then the comprehensive quality and comprehensive benefits of different treatments were respectively evaluated by principal component analysis and TOPSIS (technique for order preference by similarity to ideal solution) to obtain optimal water and N supply mode. Compared to CDI, ADI decreased tomato yield slightly, but increased water use efficiency (WUE) by 7.8%, while FDI reduced tomato yield and maintained WUE. In comparison of the five N treatments, N30-70 had higher tomato yield and lycopene and vitamin C contents and sugar/acid ratio in fruits, but it had lower organic acid content in fruits. Among all treatments, ADI-N30-70 had the optimal tomato comprehensive quality and comprehensive benefit. Therefore, ADI-N30-70 was the optimal water and nitrogen supply mode for tomato production in this study.