Cytokinins combined with activated charcoal do not impair in vitro rooting in Quercus robur L.: insights from morphophysiological and hormonal analyses

• Published in: BMC plant biology Vol. 25; no. 1; pp. 1005 - 14
• Main Authors: Martins, João Paulo Rodrigues, Mokhtari, Amir Mohammad, Wawrzyniak, Mikołaj Krzysztof
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 01.08.2025; BioMed Central; BMC
• Subjects: Acetic acid; Activated carbon; Activated charcoal; Auxin; Auxins; Benzyl Compounds - pharmacology; Benzyladenine; Botanical research; Botany; Carbon, Activated; Charcoal; Charcoal - pharmacology; Chlorophyll; Chlorophyll a fluorescence; Cytokinins; Cytokinins - metabolism; Cytokinins - pharmacology; Development; English oak; Environmental aspects; Explants; Indoleacetic acid; Indoleacetic Acids - metabolism; Jasmonic acid; Leaves; Morphology; Pedunculate oak; Photosystem II; Physiological aspects; Physiology; Plant anatomy; Plant growth regulator; Plant Growth Regulators - metabolism; Plant Growth Regulators - pharmacology; Plant Roots - drug effects; Plant Roots - growth & development; Plant Shoots - drug effects; Plant Shoots - growth & development; Plantlets; Plants; Production processes; Purines; Quercus - anatomy & histology; Quercus - drug effects; Quercus - growth & development; Quercus - metabolism; Quercus robur; Rooting; Software; Sucrose; Poland; Germany; Chlorophyll a fluorescence; Pedunculate oak; Plant growth regulator; Plant anatomy
• ISSN: 1471-2229; 1471-2229
• DOI: 10.1186/s12870-025-07064-x

In vitro rooting remains a challenge for many woody species, including Quercus robur. While auxins combined with activated charcoal (AC) have traditionally been used, Q. robur explants exhibit a strong dependence on cytokinins (CKs). This study introduces a novel approach combining AC with either 6-benzylaminopurine (BAP) or meta-topolin (mT) during the rooting phase to evaluate morphophysiological and hormonal responses. Eight treatments were tested: 0 µM CK + 2 g L AC; 2, 4, and 8 µM BAP + 2 g L AC; 2, 4, and 8 µM mT + 2 g L AC; and to isolate the effect of AC, a treatment without exogenous CK and AC (0 µM CK + 0 g L AC) was also included. Morphophysiological and hormonal analyses were performed after 40 days of cultivation. Plantlets grown without AC exhibited a high shoot-to-root biomass ratio, indicating reduced growth balance. Treatments with 0-8 µM BAP combined with 2 g L AC reduced the ratio of vascular cylinder area to total root cross-section by 16.5% compared to the other treatments. Notably, mT-treated plantlets developed root systems with improved anatomical features conducive to transport efficiency. CKs at 8 µM significantly enhanced stem thickening via stimulated cambial activity. Additionally, CK + AC treatments increased chlorophyll (Chl a + b) and carotenoid (Car) contents, while the absence of both CK and AC resulted in higher Car/Chl a + b ratios and an increased photosystem II closure rate (M ), indicating stress. Hormonally, CK-free treatments led to elevated indole-3-acetic acid (IAA) and reduced jasmonic acid (JA) levels, suggesting an imbalance. Overall, the combination of AC and 4-8 µM mT during rooting enhanced secondary growth and improved the hormonal balance and morphophysiological traits of Q. robur plantlets.