Different Drought-Tolerant Mechanisms in Quinoa ( Willd.) and Djulis ( Koidz.) Based on Physiological Analysis

The purpose of this experiment is to study the effects of treatment with 90% (28.5% volumetric water content (VWC)), 75% (24% VWC), 50% (16% VWC), and 25% (8% VWC) of water requirements on the growth of two djulis ( Koidz) varieties (red: RP and yellow: OR) and one quinoa ( Willd) varieties (PI). The results showed that drought stress (8% VWC) significantly reduced plant growth and relative water content, and increased HO and MDA content in and . The most significant increase in these parameters was detected in the OR variety. The antioxidant enzymes, such as SOD, APX, and GR activities of PI variety under drought treatment (8% VWC), are significantly increased, while GR activity of also increased significantly. Additionally, and PI variety remained at a stable AsA/DHA ratio, but the GSH/GSSG ratio decreased during drought treatment. Moreover, drought stress increased total soluble sugars and proline content in the PI variety. However, proline content was extremely significantly enhanced, and only the OR variety increased the total soluble sugar content at the same time during the vegetative growth period. In summary, and have different drought tolerance mechanisms to adapt to being cultivated and produced under severe drought conditions.