Deficit irrigation strategies are considered as promising irrigation management for water saving. In the arid areas of southern Tunisia, agriculture relies heavily on irrigation. With rainfall scarcity, valuable management of water requires efficient approaches. In this context, the effects of deficit irrigation (CDI) and partial root zone drying (PRD) on the vegetative and fruiting behaviour of an early maturing peach (Prunus persica cv. Flordastar) were investigated. Shoot and trunk growth, yield, and fruit size were evaluated during three successive years (2013–2015). In reference to full irrigation (FI) treatment, a 50% water restriction was applied using CDI and PRD. The results obtained showed that both strategies at 50% crop evapotranspiration induced a similar significant reduction of tree vigour mediated by shoot length, trunk cross‐sectional area, and pruning wood weight. Consequently, there was a significant yield loss of 25% following the continuous water restriction of 50% observed throughout the experimental period. However, these yield losses were offset by substantial water savings in the range of 48%–52% and a significant increase of agricultural water productivity. Hence, these techniques lead to significant water savings and vegetative and yield losses offset by a significant increase in water productivity.

The peach (Prunus persica L.) is one of Tunisia’s major commercial fruit crops and is considered one of the biggest water consumers of all crops. In warm and arid areas of southern Tunisia, irrigation is necessary to ensure orchard longevity and high yield and fruit quality. Nevertheless, under water-scarcity conditions and low water quality, water management should rely on efficient deficit irrigation strategies. In this study, sustained deficit irrigation (DI) and partial root-zone drying (PRD50) at 50% of crop evapotranspiration (ETc) were evaluated for their impact on the primary and secondary metabolites of the peach fruit of early cultivar Flordastar grown in the Tataouine region. A full irrigation (FI) treatment at 100%, etc., was used as a control treatment. Color, dry-matter content, firmness, organic acids, sugars, phenolic compounds, vitamin C, β-carotene and minerals were assessed on harvested mature fruits. Dry-matter content and firmness increased significantly under DI and PRD50 (13% and 15.5%). DI fruit had the highest soluble-solid content (SSC), reaching Brix values of 14.3°. Fruit sorbitol and sucrose contents were not affected by Di and PRD50. Higher glucose in fruit juice was observed in PRD50 (23%) and DI (21.5%) compared to FI, which had the highest malic acid content (33.5–37%). Quinic and citric acids decreased with DI and PRD50, while almost all individual phenolic compounds increased with deficit irrigation. Hydroxycinnamates and anthocyanins were significantly higher in fruits harvested from DI and PRD50 treatments. Proanthocyanidins (catechin and epicatechin) were only improved by DI, while flavone compounds and vitamin C were not affected by irrigation restrictions. β-carotene was higher in fruits yielded under FI (0.71 mg/100 g DM) than DI and PRD50 (0.21–0.43 mg/100 g DM). Macro- and micronutrients significantly increased in DI and PRD50 fruit. A significant difference between DI and PRD50 fruits was observed for Zn and Fe concentrations. This research highlights the positive impact of reduced irrigation on bioactive-fruit quality attributes and the suitability of PRD50 and DI as tools for irrigation management in arid areas of southern Tunisia, contributing to water-saving in orchards and the improvement of fruit commercial value.