Optimizing irrigation schedules of greenhouse tomato based on a comprehensive evaluation model

In the context of climate change, water availability has emerged as a pressing concern in agriculture, indicating the urgency to enhance irrigation management. Nevertheless, accurately quantifying irrigation schedules in diverse climates and soil textures remains a complex challenge. Here, a three-year irrigation experiment (2020–2022) of greenhouse tomato was conducted at three typical locations (Yulin, Yangling and Hanzhong) in northwest China. The irrigation schedules were determined by the cumulative evaporation (CE) measured from a 20 cm pan. A total nine treatments were set by combining three irrigation frequencies (IF) with three single doses (ID). Twenty indices related to tomato growth, photosynthesis, yield and water use, fruit quality, and environmental benefit were evaluated comprehensively by using TOPSIS (technique for order preference by similarity to ideal solution) and GRA (grey relational analysis) methods of combining weights based on game theory. The results showed that the indicator with highest weight was yield, followed by crop water productivity and vitamin C. The optimal ranges of irrigation frequency (irrigation dose) were determined as follows: 10.00–11.08 mm (0.81–0.90 CE) in Yulin, 13.12–15.68 mm (0.77–0.89 CE) in Yangling, and 11.44–16.40 mm (0.67–0.77 CE) in Hanzhong, respectively. This study introduces a method applied to prioritize the key indicators for irrigation scheduling, providing a reference for optimizing irrigation practices in greenhouse tomato production and improving water management in agriculture.