Plant Biostimulants In Pistachio (Pistacia Vera L.) Nursery and Orchard Systems: Evidence, Mechanisms and Research Priorities for Climate-Resilient Production

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.

Pistacia vera, arbuscular mycorrhizal fungi, seaweed extract

Abbaspour, H., Pour, F. S. N., & Abdel-Wahhab, M. A. (2021). Arbuscular mycorrhizal symbiosis regulates the physiological responses, ion distribution and relevant gene expression to trigger salt stress tolerance in pistachio. Physiology and Molecular Biology of Plants, 27, 1765–1778. https://doi.org/10.1007/s12298-021-01043-w

Abbaspour, H., Saeidi-Sar, S., Afshari, H., & Abdel-Wahhab, M. A. (2012). Tolerance of mycorrhiza infected pistachio (Pistacia vera L.) seedling to drought stress under glasshouse conditions. Journal of Plant Physiology, 169, 704–709. https://doi.org/10.1016/j.jplph.2012.01.014

Backer, R., Rokem, J. S., Ilangumaran, G., Lamont, J., Praslickova, D., Ricci, E., Subramanian, S., & Smith, D. L. (2018). Plant growth-promoting rhizobacteria: Context, mechanisms of action, and roadmap to commercialization of biostimulants for sustainable agriculture. Frontiers in Plant Science, 9, 1473. https://doi.org/10.3389/fpls.2018.01473

Bagheri, V., Shamshiri, M. H., Shirani, H., & Roosta, H. R. (2011). Effect of mycorrhizal inoculation on ecophysiological responses of pistachio plants grown under different water regimes. Photosynthetica, 49, 531–538. https://doi.org/10.1007/s11099-011-0064-5

Calvo, P., Nelson, L., & Kloepper, J. W. (2014). Agricultural uses of plant biostimulants. Plant and Soil, 383, 3–41. https://doi.org/10.1007/s11104-014-2131-8

Chandrasekaran, M., Chanratana, M., Kim, K., Seshadri, S., & Sa, T. (2019). Impact of arbuscular mycorrhizal fungi on photosynthesis, water status, and gas exchange of plants under salt stress: A meta-analysis. Frontiers in Plant Science, 10, 457. https://doi.org/10.3389/fpls.2019.00457

du Jardin, P. (2015). Plant biostimulants: Definition, concept, main categories and regulation. Scientia Horticulturae, 196, 3–14. https://doi.org/10.1016/j.scienta.2015.09.021

Eskandari Torbaghan, M., Sherafati, A., & Eskandari Torbaghan, M. (2025). Influence of plant growth promoting haloalkaliphilic bacteria on mitigation of salt and alkali stresses in pistachio seedlings (Pistacia vera L.). Journal of Plant Nutrition, 48. https://doi.org/10.1080/01904167.2024.2445086

European Parliament and Council. (2019). Regulation (EU) 2019/1009 laying down rules on the making available on the market of EU fertilising products. Official Journal of the European Union, L 170, 1–114.

Fattahi, M., Mohammadkhani, A., Shiran, B., Baninasab, B., Ravash, R., & Gogorcena, Y. (2021). Beneficial effect of mycorrhiza on nutritional uptake and oxidative balance in pistachio (Pistacia spp.) rootstocks submitted to drought and salinity stress. Scientia Horticulturae, 281, 109937. https://doi.org/10.1016/j.scienta.2021.109937

Khalilpour, M., Mozafari, V., & Abbaszadeh-Dahaji, P. (2021). Tolerance to salinity and drought stresses in pistachio (Pistacia vera L.) seedlings inoculated with indigenous stress-tolerant PGPR isolates. Scientia Horticulturae, 289, 110440. https://doi.org/10.1016/j.scienta.2021.110440

Nazarova, O., Khujaev, O., & Jumanazarov, G. (2023). Septoria (Septoria pistaciae Desm.) pathogen infecting pistachio nuts in Uzbekistan and its biological characteristics. IOP Conference Series: Earth and Environmental Science, 1142, 012051. https://doi.org/10.1088/1755-1315/1142/1/012051

Nikoogoftar-Sedghi, M., Rabiei, V., Razavi, F., Molaei, S., & Khadivi, A. (2023). The effect of foliar application of Ascophyllum nodosum seaweed extract on biochemical traits related to abiotic stresses in pistachio (Pistacia vera L. cv. Kaleh-Ghoochi). BMC Plant Biology, 23, 635. https://doi.org/10.1186/s12870-023-04654-5

Nikoogoftar-Sedghi, M., Rabiei, V., Razavi, F., Molaei, S., & Khadivi, A. (2024). Fulvic acid foliar application: A novel approach enhancing antioxidant capacity and nutritional quality of pistachio. BMC Plant Biology, 24, 241. https://doi.org/10.1186/s12870-024-04974-0

Paymaneh, Z., Sarcheshmehpour, M., Mohammadi, H., & Hesni, M. A. (2023). Vermicompost and/or compost and arbuscular mycorrhizal fungi are conducive to improving the growth of pistachio seedlings to drought stress. Applied Soil Ecology, 182, 104717. https://doi.org/10.1016/j.apsoil.2022.104717

Rouphael, Y., & Colla, G. (2020). Biostimulants in agriculture. Frontiers in Plant Science, 11, 40. https://doi.org/10.3389/fpls.2020.00040

Safipour Afshar, A., & Abbaspour, H. (2023). Mycorrhizal symbiosis alleviates salinity stress in pistachio plants by altering gene expression and antioxidant pathways. Physiology and Molecular Biology of Plants, 29, 263–276. https://doi.org/10.1007/s12298-023-01279-8

Salimi, F., Khorshidi, M., Amirahmadi, F., & Amirahmadi, A. (2023). Effectiveness of phosphate and zinc solubilizing Paenarthrobacter nitroguajacolicus P1 as halotolerant rhizobacterium with growth-promoting activity on Pistacia vera L. Current Microbiology, 80, 336. https://doi.org/10.1007/s00284-023-03448-0

Sharma, H. S. S., Fleming, C., Selby, C., Rao, J. R., & Martin, T. (2014). Plant biostimulants: A review on the processing of macroalgae and use of extracts for crop management to reduce abiotic and biotic stresses. Journal of Applied Phycology, 26, 465–490. https://doi.org/10.1007/s10811-013-0101-9