Wild barley (Hordeum spontaneum) is a highly invasive weed in wheat fields. Quinoa (Chenopodium quinoa), a halophytic plant rich in phenolic compounds exhibited allelopathic potential. Its seeds contain a bitter, toxic outer layer of saponins. This study investigated the allelopathic effects of quinoa-derived saponin and plant residues on wild barley under laboratory, greenhouse and field conditions during 2022-2023. Results confirmed that both saponin and quinoa residues exerted significant allelopathic herbicidal effects on wild barley. There is little work on allelopathic effects of quinoa saponin on weeds or crops.