The efficacy of allelopathy of select lichens on antioxidant potential and proliferation of Ceratophyllum demersum L.

The exploration of natural plant growth enhancers is crucial for sustainable agriculture and environmental conservation, as well as for discovering new sources of bioactive compounds with pharmacological potential. In this study, we aimed to investigate growth-promoting effect of Dermatocarpon miniatum and Parmelia saxatilis lichens on Ceratophyllum demersum propagated in vitro. Furthermore, we revealed antioxidant capacity variation (DPPH scavenging and metal chelating activities, as well as total phenol and flavonoid contents) in lichen-treated plant (allelopathic plant). C. demersum was subjected to methanol and water extracts from lichens, specifically D. miniatum and P. saxatilis. For P. saxatilis, the methanol extract at 90 mg/L achieved the highest shoot number (189.13 shoots) and the longest shoot length (4.86 cm) using a 50 mg/L water extract. Notably, IC₅₀ values revealed that water extracts from allelopathic plants were the most effective, with the lowest IC₅₀ value of 48.20 mg/L for metal chelation and 53.60 mg/L for DPPH scavenging. In addition, the total phenol and flavonoid contents were significantly higher in allelopathic plants than in control plants. The methanol extract from allelopathic samples contained the highest phenol content (73.93 µg gallic acid equivalent/mg extract) and flavonoid content (66.26 µg µg quercetin equivalent/mg extract). In conclusion, this study will provide valuable input for future investigation in domain of plant development control and augmentation of biologically active substance propagation in plants, with a particular focus on utilizing P. saxatilis lichen.