An experiment was conducted based on a split plot arrangement in a randomized complete block design with three replicates during 2019-2020. Experimental factors included drought stress at three levels (50, 80, and 110 mm evaporation from evaporation pan Class A), cultivar at two levels (Titicaca and Q29), and organic acids at four levels (control, humic acid, amino acid, and a combination of humic and amino acids). Findings suggested that extreme drought stress resulted in the decreasing of 20.33% plant height, 30.19% of leaf area index while increasing of 78.69% malondialdehyde content as well as 38.12% of catalase and 31.26% of peroxidase enzymes activities. Titicaca cultivar had higher plant height, leaf area index and catalase contents in amounts of 3.32%, 9.98% and 13.38% as compared with Q29. Applying organic compounds improved growth and biochemical properties of quinoa plants with the maximum positive effect in plants treated with a combination of humic and amino acids. As well as the using of these compounds decreased the negative effects of drought stress. Application of humic and amino acids seems to improve vegetative parameters of quinoa plants under both normal and drought stress conditions though increasing antioxidant enzyme activities and regulation of abscisic acid hormone. تفاصيل المقالة