Biostimulants Use to Improve Quality and Stress Resistance of Echinocereus rigidissimus var. rubrispinus and Bulbine abyssinica

The use of biostimulants is gaining increasing importance as a sustainable strategy to improve plant growth, quality, and tolerance to abiotic stress in ornamental horticulture. This study evaluated the effects of different biostimulant approaches on Echinocereus rigidissimus var. rubrispinus and Bulbine abyssinica grown in pots under greenhouse conditions during the winter–spring season at the Pescia, CREA Research Centre for Vegetable and Ornamental Crops. All treatments were applied in combination with a uniform fertilization program. Six treatments were compared: fertilized control, Inula viscosa extract, electroculture, Inula viscosa combined with electroculture, a commercial seaweed-based product derived from Ascophyllum nodosum, and a microbial inoculum containing Glomus mosseae and Rhizophagus irregularis. Growth parameters, root development, chlorophyll content (SPAD index), ornamental quality, and stress tolerance under controlled drought conditions were assessed. Results showed that all biostimulant treatments significantly improved plant performance compared to the control. The combined application of Inula viscosa and electroculture produced the highest increases in vegetative growth, biomass accumulation, and chlorophyll content in both species, indicating a synergistic effect. The mycorrhizal treatment markedly enhanced root system development and improved plant survival under water deficit conditions. The seaweed-based product provided consistent improvements in plant vigor and ornamental traits. Overall, the integration of plant extracts, beneficial microorganisms, and physical stimulation techniques demonstrated a strong potential to enhance both growth and stress resilience in succulent and xerophytic species. These findings support the adoption of combined biostimulant strategies as an effective tool for sustainable ornamental plant production under greenhouse conditions.