Fuente: ISHS (International Society for Horticultural Science) Post date: Monday 1 December 2025
Author:
ISHS Secretariat

The pistachio (Pistacia vera L.) is a highly resilient crop, capable of tolerating several abiotic stresses, including water shortage. Due to this, it is traditionally cultivated in dry conditions in the Mediterranean region, including Sicily. However, the lack of irrigation often causes physiological limitations and agronomic issues, such as reduced CO2 assimilation, alternate bearing, poor nut quality, and reduced yields. Even though pistachios are drought-tolerant, maintaining a sufficient water supply is crucial to sustain high productivity. This study aimed to investigate the response of mature pistachio trees to different water supply levels to improve irrigation management in Sicilian orchards. The experiment was carried out in the Caltanissetta area on trees of the ‘Bianca’ cultivar grafted onto Pistacia terebinthus L. Three water regimes were compared: rainfed (T0), 50 mm ha-1 (T1), and 100 mm ha-1 (T2), applied during fruit development, from June to August 2024. The physiological measurements included maximum net photosynthesis rate (Amax), stomatal conductance (gs), intrinsic water use efficiency (WUEi), and midday stem water potential (SWP). Although the water supplied was very limited in T1 and T2, it enabled the trees to sustain a higher water status than the rainfed ones throughout the entire growing season. Stomatal conductance and assimilation rates were also higher in the irrigated treatments, confirming that supplemental irrigation reduces stress during the production season. However, the opposite situation was observed in terms of water use efficiency. A sharp decline in photosynthesis and stomatal conductance occurred when the SWP dropped below -1.5 MPa, indicating the onset of severe water stress conditions. Despite these physiological benefits, no significant differences were observed among treatments in yield parameters, such as nut number and kernel weight per tree in the first year. This study demonstrates that small amounts of water were beneficial in enhancing the physiological performance of the plants. However, to assess the effects on production, it will be necessary to observe the physiological responses over a longer term, considering also the species’ alternate bearing behavior.
Valeria Imperiale won the ISHS Young Minds Award for the best poster presentation at the I International Symposium on Temperate Tree Nuts: from Agroecologically Sustainable to Organic Production in Italy in August 2025.
Contact: Valeria Imperiale, University of Palermo, Department of Agricultural, Food and Forest Sciences, Viale delle Scienze, Ed 4, 90128 Palermo, Italy, e-mail: valeria.imperiale@unipa.it
The article is available in Chronica Horticulturae.Tags: pistachioCategories: Young Minds Award Winners