Modeling the Relationship of Tomato Yield Parameters with Deficit Irrigation at Different Growth Stages

Abstract

Greenhouse experiments were conducted in 2017 and 2018 to investigate quantitative relationships between tomato yield parameters and deficit irrigation at different growth stages. Tomato plants received one of three irrigation treatments (full irrigation, 2/3, and 1/3 full irrigation) at flowering and fruit development (stage 2) and at fruit maturation (stage 3); no deficit irrigation treatments were applied at stage 1 during either season. We used linear regression to investigate how well the yield parameters such as whole-plant yield (Y), single-fruit weight (y), fruit diameter (D), and length (L) were correlated with seasonal evapotranspiration (ET) under different deficit irrigation treatments. Six water–yield models (Blank, Jensen, Singh, Stewart, Minhas, and Rao models) were used to predict the tomato yield parameters with deficit irrigation at different growth stages. The results showed that deficit irrigation at each growth stage significantly decreased ET, Y, y, L, and D, but not T1 (2/3 full irrigation at flowering and fruit development). T1 produced higher water use efficiency (WUE) with no significant decrease in yield parameters, indicating that an acceptable balance between high WUE and yield can be obtained with an appropriate water deficit at stage 2. Relative Y, y, D, and L increased linearly as relative seasonal ET increased. Water deficit sensitivity indexes calculated by the six different water–yield models showed that Y, y, D, and L were more sensitive to water deficit at stage 2 than at stage 3. The values of Y calculated by the Minhas and Singh models were similar to the observed values. The Minhas model provided good estimates of L and D, and the Blank model is recommended for calculating y when there is a water deficit at different growth stages. The water–yield models can be used to optimize irrigation water management and provide a sound basis for efficient tomato production.