The current study was aim to evaluate the interaction effects of gamma aminobutyric acid (GABA) and vermicompost on yield and yield components of quinoa under different levels of drought stress. For this, two experiments were similarly designed as the factorial-split with four replicates for evaluating this hypothesis. Irrigation regimes (50, 75, and 100 % of plant water requirement (PWR)) as the main plot and vermicompost V (0, 5 t ha-1) × gamma aminobutyric acid GABA levels (0, 5, 10 mg l-1) as the subplot were designed. Severe drought stress had a significant effect on plant height. Plant height reduced 31.8 % after using 50 % of PWR compared to the control conditions. Although drought stress negatively affected the 1000 seed mass and seed yield, GABA foliar application alleviated these effects. After using 50 % of PWR, 10 mg l-1 of GABA increased the seed yield and harvest index up to 21.22 and 15.5 %, respectively, compared to the non-foliar application. The reduction in PWR from 100 to 50 % led to increasing in P and K concentrations, as well as sugar and proline contents. In the same conditions, the use of GABA or V had a significant effect on improving these traits. A similar trend was also recorded in relation to water use efficiency. Therefore, using 10 mg l-1 of GABA and 5 t ha-1 of V can be effective in alleviating water stress.

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