Unravelling the impact of plant ontogenic factors on the content and phytotoxic potential of Cistus ladanifer L. (rockrose) essential oils

In recent years, research has focused on the development of next-generation herbicides based on allelochemicals, with a particular emphasis on plant essential oils, such as Cistus ladanifer L. (rockrose) essential oil. This study has evaluated how plant ontogenic factors influence the yield, chemical composition, and phytotoxic activity of C. ladanifer essential oil. The essential oils were extracted by hydrodistillation and analysed by gas chromatography coupled with mass spectrometry (GC-MS). The results revealed that the content of essential oil varied significantly, with higher yields observed during the fruit maturation stage compared to the flowering stage. C. ladanifer essential oils were characterized by their richness in terpene-oxygenated compounds. The most significant finding was that C. ladanifer essential oil displayed potent dose-dependent phytotoxic activity on Raphanus sativus (radish) seedlings, indicating their potential use as a natural bioherbicide in agriculture. Notably, essential oil samples from the fruit maturation stage, which contained higher levels of monoterpenes and sesquiterpenes (both hydrocarbons and oxygenated forms), exhibited greater phytotoxic activity on seed germination and early growth compared to the samples from the flowering stage, which were richer in diterpenes and the group labelled "others". Multivariate analyses (PCA and Heatmaps combined with cluster analysis) revealed concordance between modifications in secondary metabolism biosynthetic pathways and their enzymes implicated as responses to diverse plant-specific ecological functions. Finally, by exploring sustainable natural products like plant essential oils, this research contributes to the development of next-generation herbicides that promote crop protection while reducing environmental impact.