Effect of Spermidine and Salicylic Acid Application on the Morphological and Physiological Characteristics of Quinoa (Chenopodium quinoa) Under Salt Stress Conditions

To investigate the growth and physiological response of the halophyte quinoa plant to the application of salicylic acid and spermidine under salt stress conditions, two experiments were conducted under field and greenhouse conditions in the Jofair region of Khuzestan province in 2019. The findings indicated that salinity significantly increased root membrane electrolyte leakage while reducing root volume and relative water content. It was observed that the most severe salinity stress (24 dS/m) resulted in the highest membrane electrolyte leakage and lowest root volume and relative water content. Additionally, salinity escalation led to a notable rise in antioxidant activity, including superoxide dismutase, catalase, and peroxidase. On the other hand, treatments involving salicylic acid and spermidine effectively alleviated the negative consequences of salinity stress on the Quinoa plant by enhancing its anti-stress capabilities. Specifically, the application of 1.5 mM of salicylic acid and spermidine exhibited increased relative water content and root volume, as well as enhanced antioxidant enzymes such as SOD, CAT, POX, and proline. This treatment also reduced ion leakage and hydrogen peroxide levels. The findings of the present study suggest that the applied salicylic acid and spermidine positively impacted the Quinoa plant's ability to alleviate the negative effects of salinity stress.