ABSTRACT Efficient irrigation management is essential for improving water productivity in semiarid Mediterranean agriculture. This study evaluated the effects of regulated deficit irrigation (RDI) on plant growth, yield components and water use efficiency (WUE) of open‐field processing tomato during two growing seasons (2023–2024). Three irrigation regimes were tested: full irrigation (T1, 100% ETc), mild deficit (T2, 80% ETc) and moderate deficit (T3, 60% ETc). Experiments were conducted under field conditions using a replicated design, with real‐time soil moisture monitoring to support irrigation scheduling. Plant growth indicators, yield components, fruit size and WUE were evaluated, and treatment effects were analysed using analysis of variance. The results showed that T2 maintained vegetative growth and total yield statistically comparable to full irrigation ( p > 0.05) while reducing irrigation water by approximately 14%–16%. In contrast, T3 significantly reduced the total and marketable yield ( p < 0.05), with yield decreases of approximately 42% in 2023 and 32% in 2024. WUE was significantly higher under T2, increasing by 36% in 2023 and 15% in 2024 compared with T1 ( p < 0.05). These findings indicate that mild deficit irrigation (80% ETc) can improve water productivity without compromising yield, highlighting its potential as a practical irrigation strategy for water‐limited Mediterranean agricultural systems.
Ahmia et al. (Thu,) studied this question.