In vitro rooting of Quercus robur, activated charcoal vs. exogenous auxin: a morphophysiological approach

In plant cultivation, morphophysiological status of the plantlets is crucial. We aimed to assess how activated charcoal (AC) and synthetic auxins, separately and in combination, affect the biochemistry, anatomy, and physiology of Quercus robur plantlets. Two concurrent experiments were conducted using indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) as exogenous auxins, with or without AC. Plantlets grown without exogenous auxins and AC displayed weak root development, reduced functionality, lower photosynthetic pigments, and elevated starch and free IAA content. Incorporating IAA or IBA into the medium triggered positive morphophysiological changes, such as aerenchyma formation, increased hydrogen peroxide, and reduced free IAA levels in the in vitro-produced clones. Plantlets cultured with 2 g L −1 AC exhibited higher biomass and more photosynthetic pigments. AC also enhanced the photosynthetic apparatus, as indicated by higher total performance index (PI (TOTAL) ) values. Importantly, AC improved rooting success and overall morphophysiological condition, regardless of exogenous auxin presence. These findings provide novel insights into in vitro rooting modulation with AC and exogenous auxins, promising advancements in the growth and performance of Q. robur plantlets. Key Message Exogenous auxin supplementation is not a limiting factor for rhizogenesis. Root functionality was a response to physiological disorders. AC can induce plantlets with higher connectivity of the photosystem II units.