Physiological and biochemical interactions between Avena fatua and Artemisia austriaca in a co-cultivation system

Plant-plant interactions are major factors shaping the structure and functioning of agroecosystems. Competition for resources and potential biochemical interactions among plants can provide valuable insights for agricultural practices, including weed management and improving crop quality. The present study investigated the biochemical and physiological interactions between Artemisia austriaca Jacq., a medicinal and aromatic plant, and the model weed Avena fatua L. Co-cultivation significantly altered growth and physio-biochemical traits in both species. Growth inhibition was more pronounced at higher plant densities, reaching up to 54.94% reduction in biomass of A. fatua and up to 77.07% reduction in root fresh weight of A. austriaca . While shoot growth for A. fatua remained largely unaffected, there was a reduction of 40.29% in root length and a 25.58% decrease in total plant length. In contrast, A. austriaca exhibited stronger sensitivity, with reductions up to 46.99% in root length and 43.06% in total length. Photosynthetic pigments increased at moderate densities (up to 48.94% in chlorophyll a ), but declined at higher densities. Increased o​xidative stress markers, including hydrogen peroxide ( by up to 73.83%​) and malondialdehyde (by up to 5.16-fold), indicated stress-induced damage. Antioxidant enzyme responses were species-dependent, with peroxidase activity increasing up to 2.49-fold. Co-cultivation also modified the essential oil composition of A. austriaca , notably increasing the 1,8-cineole content by up to 53.36%. These findings highlight strong inhibitory interactions under co-cultivation, particularly the suppressive effect of A. fatua on A. austriaca and the stimulatory effect of A. fatua on some A. austriaca essential oil constituents. Future applications may include optimizing plant density and species combinations in agroecosystems to exploit the potential of these interactions for natural weed suppression, thereby reducing reliance on synthetic herbicides while enhancing crop productivity and ecological sustainability.