Vol. 8 No. 09 (2026): Volume 08 Issue 09

Pistachio (Pistacia vera L.) is adapted to dry environments, yet nursery plants and bearing orchards remain vulnerable to drought, salinity, heat, nutrient imbalance and disease pressure. Plant biostimulants are increasingly proposed to improve nutrient-use efficiency and stress tolerance, but evidence varies among product classes and experimental settings. This critical review evaluates direct evidence from pistachio and distinguishes it from mechanistic inference derived from other crops. Arbuscular mycorrhizal fungi (AMF) provide the most consistent pistachio-specific evidence. Controlled studies report improvements in biomass, mineral acquisition, water relations, photosynthetic performance, ion homeostasis and antioxidant regulation under drought or salinity, although responses depend on rootstock and stress intensity. Indigenous plant growth-promoting rhizobacteria (PGPR) also improve physiological traits under saline and water-limited conditions, but strain persistence and field reproducibility remain uncertain. Foliar Ascophyllum nodosum extract and fulvic acid have produced promising orchard-level biochemical and nutritional responses, whereas robust multi-year evidence for yield stability, nut quality and disease suppression remains limited. Regional research in Uzbekistan has confirmed Septoria pistaciae in pistachio, demonstrating that disease pressure is relevant to local production systems; however, pathogen occurrence should not be conflated with evidence of biostimulant-mediated control. Future research should use characterized products, rootstock-aware designs and multi-stress trials that measure physiological mechanisms alongside seedling survival, disease incidence and severity, marketable yield and economic return. Biostimulants should be treated as context-dependent components of integrated water, nutrient, soil and plant-health management rather than stand-alone substitutes for established agronomic and disease-management practices.