Abstarct: An experiment was conducted to evaluate the allelopathic potential of root, stem, and leaf organs of two ornamental and medicinal plants, Bird paradise (Strelitzia reginae Ait.) and Anthurium, on the morphological, physiological, and biochemical characteristics of the immigrant plant of quinoa under hydroponic culture conditions. These experiments were carried out as two completely random designs in three replication in the botanical laboratory of Gonbad Kavos University in 2022. In this study, morphological traits such as roots and stem length, number of leaves, dry weight of roots, stems and leaves, physiological (relative leaf water content, the content of pigments i.e., chlorophyll a, b content, total chlorophyll content (a+b), carotenoids content, ratio of chlorophyll a to b, proline, soluble sugars, catalase activity, ion leakage and biochemical such as total phenol and flavonoid content as well as antioxidant activity were measured. The results of these study showed that the leaf organ had the highest allelopathic effect on the morpho-physiological and biochemical characteristics of quinoa. So that the extracts of different organs of Strelitzia reginae and Anthurium showed different effects on the treated plant of quinoa. In general, the different organs etracts of Strelitzia reginae and Anthurium showed significant decreasing and increasing effects on the morphological, physiological and biochemical characteristics of the studied seedlings, respectively. Also, the decrease in the ratio of chlorophyll a to b pigments, and the increase in the osmolytes of proline and soluble sugars, the activity of catalase enzyme, the content of total phenol and flavonoids in quinoa seedlings treated with the aqueous extract of Strelitzia reginae organs may be used as parameters of abiotic stress. In general, due to the widespread use of ornamental and medicinal flowers, especially Anthurium and Strelitzia reginae, as cut branches in commercial greenhouses and the lack of proper utilization of their biomass in domestic and industrial uses, their effective compounds can be considered as candidates for extracting and exploiting their effective substances, it may be considered as a candidate for the production of hormones (reinforcement fertilizers), drugs, edible plant and even herbicides with biological origin in sustainable agriculture. This requires phytochemical analysis of compounds in these plants along with additional test.