In the case of young sorghum plants, the addition of quinine hydrochloride or quinine-based QASs at a concentration of 10 g dm -3 or lower did not cause statistically significant changes in root or shoot length compared to the control. Thus, no phytotoxic effect of the obtained compounds was observed toward sorghum. Since growth inhibition was not observed at a statistically significant level for white mustard either, it can be concluded that application of the obtained QASs on the stored grain for pest protection will not cause phytotoxic effects.