The effect of ascorbic acid foliar application on grain yield and some physiological traits of quinoa under water stress conditions

In order to investigate ascorbic acid effect on grain yield and some physiological traits of quinoa plant under water deficit stress conditions, an experimental in the form of split plots based on the randomized complete block design with three replications in two years at Research and Agriculture and Natural Resources Center Kerman was performed. The main factor included three levels of irrigation treatments (irrigation to the full maturity stage (control), irrigation to the beginning of the flowering stage, and irrigation to the beginning of the dough development stage) and the secondary factor included two levels of ascorbic acid foliar spraying (0 and 2 mM). The effect of irrigation factor and ascorbic acid and their interaction on seed yield and most of the measured physiological traits were significant. Water stress decreased grain yield, content of photosynthetic pigments, leaf protein content and relative water content and increased carbohydrate and proline content. The seed yield decreased by 40.5% and 18.7% under the conditions of irrigation to the beginning of the flowering stage and irrigation to the beginning of the dough development stage, respectively, compared to the control conditions. Foliar spraying with ascorbic acid led to the improvement of physiological traits and grain yield in all three irrigation treatments. Seed yield increased by 22.7% with ascorbic acid solution. Since foliar spraying with ascorbic acid improved seed yield in three irrigation treatments, it is suggested to use this substance to compensate for the damage caused to quinoa plant as a result of drought stress.