Fine droplet misting and stage-specific nutrient formulation enhance bed-area biomass productivity and nutrient solution use efficiency in closed-loop aeroponic Centella asiatica

Ju Young Lee, Jae‐Joong Kim, Jai-Eok Park

Closed-loop aeroponics exposes suspended roots to repeated pulses of nutrient solution and humid air, so nozzle and misting settings shape the root-zone water, nutrient, and gas environment. We evaluated how root-zone droplet delivery and stage-specific ion management affected growth and nutrient solution-use efficiency of Centella asiatica in a natural-light greenhouse. Six nozzle classes were characterized by laser diffraction, and three misting schedules were screened using shoot dry-mass production efficiency. A separate bed-level experiment compared fresh and dry biomass under four operationally feasible nozzles, while a nutrient-management experiment compared fixed Hoagland, EC-adjusted Hoagland, and a stage-specific formulation using shoot and root biomass, leaf and runner number, SPAD, canopy cover, and solution-use efficiency. The plantable bed area was 63.9 m² within a 165 m² greenhouse, at a density of approximately 16–25 plants m − ². VF and F treatments achieved the highest dry-mass production efficiency, and the 5 min × 288 events day − ¹ schedule performed best across nozzle classes. At 53 days after transplanting (DAT), VF produced the greatest fresh and dry biomass per bed area within the tested C–M–F–VF range. The stage-specific formulation produced greater shoot and root biomass, canopy cover, and solution-use efficiency than either Hoagland treatment. Reservoir corrections were greatest for nitrate during leaf expansion, potassium during biomass accumulation, and Ca, Fe, and B during late maturation. Taken together, the complementary experiments associated root-zone delivery and stage-specific nutrient supply with coordinated whole-plant growth and resource-use responses. Because root-surface wetness, oxygen availability, root respiration, and tissue ion accumulation were not measured directly, nozzle effects should be interpreted as integrated root-zone treatment effects rather than effects of droplet diameter alone. Multi-season factorial experiments with direct physiological measurements are needed to confirm the underlying mechanisms.