Characterization of biochemical traits, volatile compounds, and sensorial attributes of pistachio (Pistacia vera L.) nuts and oil as affected by regulated deficit irrigation and roasting

Prolonged drought poses a critical challenge for pistachio cultivation in Mediterranean regions. Water-saving strategies and selecting adapted cultivars can help maintain sustainable production. This study was conducted in the experimental orchard of the Regional Center of Agricultural Research of Sidi Bouzid, Tunisia. Four pistachio cultivars (Mateur, Elguetar, Kerman, and Ohadi) grafted on P. atlantica rootstock were used to investigate the impact of regulated deficit irrigation (RDI) on yield, nut composition, volatile compounds, phenolic compounds, fatty acid profile, and sensory analysis. Three irrigation treatments were applied: control (T0) received 100% crop evapotranspiration (ETc) during all stages of nut development; RDI treatment (T1) received 50% ETc during stages I and II of nut development, followed by 100% ETc during stage III; and stressed treatment (T2) received 50% ETc during two growing seasons (2017 and 2018). Pistachio nuts were immersed in a solution of NaCl (5% w/v) for 5 min and then introduced in an oven for 2 h at 120 degrees C to obtain 'roasted' pistachio for volatile and sensorial analysis. Results showed that RDI saved 20% of irrigation water during stages I and II of nut development while maintaining similar yield, nut composition, and fatty acid profile as that of control. Moreover, the volatile compounds content and oil yield were enhanced under drought stress. Roasting enhanced the perception of volatile compounds, especially nitrogenous ones. Cultivars Mateur and Ohadi showed high sensory quality, with Ohadi achieving the highest consumer satisfaction despite lower yield and dehiscence rate. Cultivar Mateur was suitable for high-density planting in semiarid environments. Overall, RDI proved effective for increasing water use efficiency without compromising pistachio quality, suggesting its suitability for arid and semiarid orchards.