USE OF A BIOSTIMULANT BASED ON INULA AND CHABAZITIC ZEOLITITE ON POTTED OLIVE TREES (Olea europaea): A SCIENTIFIC STUDY

The present study evaluated the effects of a biostimulant formulation based on Inula viscosa, beneficial microorganisms, and algae (INORT), in combination with chabazitic zeolitite (ZEO), on the growth and physiology of potted olive trees (Olea europaea L., cv. ‘Koroneiki’). Five treatments were compared under greenhouse conditions: a control (peat 80 % + pumice 20 %), algae Kelp (AG), INORT, zeolitite (ZEO; peat 80 % + zeolite 20 %), and the combined treatment INORT + ZEO. Plants were irrigated with water or 1 % biostimulant solutions (25 mL plant⁻¹ week⁻¹) over a 24-week growth cycle. Morphological, physiological, and substrate parameters were analysed, including plant height, leaf area, biomass, chlorophyll content, photosynthetic rate, and substrate nutrient characteristics. Results showed that INORT and ZEO each improved growth compared with the control, while the combined INORT + ZEO treatment produced the highest values for plant height (68 cm), total leaf area (1.61 m²), and shoot dry weight (26.5 g). Photosynthetic rate and stomatal conductance were significantly increased, accompanied by higher chlorophyll content and improved foliar K and Mg concentrations. Substrate water-holding capacity and cation exchange capacity were 25–30 % higher in zeolitite-amended pots, leading to greater availability of K⁺ and NH₄⁺. The synergistic interaction between the Inula-based biostimulant and chabazitic zeolitite enhanced both physiological efficiency and nutrient retention, resulting in superior vegetative development. The combined use of biological and mineral amendments represents a sustainable strategy for improving growth performance and resource-use efficiency in containerised olive cultivation. Keywords: Photosynthetic Efficiency; Nutrient Uptake; Water Retention Capacity; Sustainable Horticulture; Rhizosphere Interactions