*2.5. Determination of Non-Enzymatic Antioxidant Compounds*

The leaf sample (0.2 g) was homogenized in 10 mL of 80% ethanol to determine the total phenolic and flavonoids. The ethanolic extract was then centrifuged at 12,000× *g* for 20 min at 4 ◦C, and the supernatants were collected in the flask. The supernatant was then utilized to determine the total phenolic and flavonoid content.

The total flavonoid content (TFC) in the sample was determined using a modified aluminum chloride assay reported [25] with rutin as standard. Briefly, 1 mL of the extract was placed in a 10 mL volumetric tube. To begin, each volumetric flask was filled with 2 mL of 0.1 M AlCl3 and incubated for 5 min. Then, 3 mL of 1 M CH3COOK was added; the volume was topped up 10 mL with 80% ethanol and thoroughly mixed. At 420 nm, the absorbance was measured against a blank using a UV/Vis spectrophotometer (UV 2700, Shimadzu, Japan). The results were expressed in mg rutin equivalents per gram dry weight.

The concentration of total polyphenol content (TPC) was determined using the Folin– Ciocalteu colorimetric technique with minor modifications [26]. Briefly, 1.5 mL distilled water was added to 0.5 mL extracted plant samples in a test tube. After adding 0.2 mL FC reagent, the mixture was gently oscillated and maintained at room temperature for 4 min. Following that, each sample was vortexed with 0.8 mL of newly prepared 10% (*w*/*w*) Na2CO3. The mixtures were left for 1 h in a dark room condition to ensure a good reaction. The absorbance of the solution was determined using a UV/Vis spectrophotometer (UV

2700, Shimadzu, Japan) at 765 nm compared to the reagent blank. To estimate all of the determinations, three biological replications were carried out. The total phenolic content was reported in milligrams of gallic acid standard equivalent (mg) dry weight (mg of GAE/g DW).

#### **3. Statistical Analysis**

The data were examined using the one-way analysis of variance (ANOVA) using SPSS 16. The effect of treatment of each variety was determined compared to the control, and the statistical differences between control and treatment were performed using a least significant difference (LSD) test when *p* < 0.05. The correlation coefficient was determined using Pearson's correlation coefficient. All data were transformed to stress tolerance indices prior to Pearson's correlation, principal component analysis (PCA), and cluster analysis. The stress tolerance index was described as the observed value of a target trait when subjected to a particular level of stress divided by its mean value under control. To investigate the relationship between varieties and cluster features, principal component analysis (PCA) and cluster heat map analysis were performed using the Origin software and an online ClustVis application, respectively.

#### **4. Results**
