Influence of water spraying intervals and indole-3-butyric acid concentrations on Salvia rooted cuttings quality in a closed aeroponics system

Aeroponics, a soilless cultivation system where plants grow suspended in air and nutrient solution is sprayed directly onto the root system, can potentially optimize clonal stem cutting propagation. Here, we evaluated the effects of water spray intervals and the Indole-3-butyric acid (IBA) treatment on adventitious root development and the quality of ornamental sage cultivar cuttings. The investigation focused on three factors: (a) spray intervals of 5 (I5) and 10 min (I10); (b) IBA of 0 g L⁻¹ (C0 - control) and with a concentration of 1 g L⁻¹ (C1); and (c) sage cultivars 'Farina Silver Blue' and 'La Siesta'. A significant interaction was found between spray interval and IBA concentration in developing rooted cuttings. Specifically, applying 1 g L⁻¹ IBA with the longer spray interval of I10 positively influenced the percentage of cuttings with first roots at seven days post-cutting, the proportion of rooted cuttings, and the number of roots per cutting at 21 days post-cutting. The I10 spray interval yielded higher adventitious root quality than I5. No significant differences were observed between IBA concentrations regarding root length, root area, or the number of tips, forks, and crossings, whereas untreated cuttings exhibited greater root diameter and volume. Statistical analysis further indicated that combining 1 g L⁻¹ IBA with the I10 spray interval resulted in significantly higher root biomass yield. These findings suggest the potential for sustainable cutting production. Enriching aeroponics with these elements enables healthy, high-quality plant cultivation without using non-renewable resources. Aeroponics may also serve as a foundational technology for emerging systems like vertical farming.