A Turkish nursery trial has shown that ultra-low concentrations of wood vinegar — applied weekly as a foliar spray — significantly boosted root and shoot development in Black Chokeberry (Aronia melanocarpa) saplings, while higher doses proved toxic. The findings appear in Notulae Botanicae Horti Agrobotanici Cluj-Napoca (2026).
Researchers at Karadeniz Technical University tested six wood vinegar concentrations (0.01%, 0.1%, 0.5%, 1%, 5%, and 10%) against a distilled-water control over nine weeks in controlled growth chambers. Each treatment comprised three replicates of 104 micropropagated saplings grown in cocopeat-peat-perlite substrate, receiving weekly foliar sprays scaled from 0.1 mL to 1 mL per sapling as plants matured.
The 0.01% treatment delivered the longest roots (9.7 cm, nearly triple the control’s 3.6 cm), while 0.1% wood vinegar produced the tallest shoots (9.1 cm vs. 8.0 cm control). Both low concentrations also increased root collar diameter significantly. The 1% treatment recorded the highest survival rate among wood vinegar groups (62.5% vs. 37.5% control) and lifted shoot numbers to 1.19 per sapling. The study wasn’t designed to separate wood vinegar’s individual contribution from broader growth-medium effects, but the concentration-response pattern across treatments was clear and consistent.
Concentrations of 5% and 10% induced severe phytotoxicity — near-total mortality prevented any morphological measurement, and those groups were excluded from analysis. The effect threshold was sharp: promotional at 0.01–1%, destructive beyond.
The researchers attribute the low-dose growth promotion to wood vinegar’s acetic acid and phenolic content, which may enhance nutrient availability in the rhizosphere and support root architecture. High-dose toxicity likely reflects osmotic stress or cellular damage from excessive organic acid exposure. The foliar application method was chosen for rapid stomatal absorption, minimising substrate immobilisation.
Aronia cultivation relies heavily on controlled propagation systems; defining safe application windows matters for commercial adoption. These results show wood vinegar — a pyrolysis by-product of forestry waste — can function as a biostimulant when applied at the right rate, offering nurseries a low-input alternative to synthetic growth regulators. The study frames this as a circular-economy link between forestry residues and sustainable horticulture, though practical adoption will require field-scale validation and cost-benefit analysis.
Full paper: Oktan, E., Özkan, Ö., & Ölmez, Z. (2026). Biostimulant effects of wood vinegar on the growth of Aronia (Aronia melanocarpa (Michx.) Elliott) saplings and its evaluation in terms of sustainability. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 54(3), 15249. https://doi.org/10.15835/nbha54315249
