*4.6. Principle Component Analysis (PCA)*

PCA is a multivariate exploratory technique used to reduce the multidimensionality of the facts and provide a two-dimensional map that explains the determined variance. In the PCA analysis, eigenvalues greater than 1 were regarded as significant and loading plots allowed for easy visualization of biochemical parameters and varieties of *C. capsularis* and *C. olitorius* (Figure 5). Cumulative PCA biplot contributes 88.36% of the total variability of the studied parameters, while PC1 accounts for 78.98% and PC2 accounts for 9.38% of the original data in this study. The angle of the trait vectors reflected the correlation of variables. A lower angle between distinct factors pointing in the same direction suggested a strong correlation between the respective varieties' classification criteria. The broad spectrum distribution of measured parameters in this biplot showed the differential correlation (positively and negatively to different PC groups) with each other. SOD, APx, proline, soluble sugar, total polyphenols (TPC), and POD were clustered on the right upper side of the biplot with positive loading, indicating that these parameters exhibited a significant degree of positive correlation among themselves. Total flavonoids, CAT, GSH, total chlorophyll, and carotenoid were all located on the right lower side of the biplot, indicating a positive association between these measures. MDA and H2O2 were detected on the left upper section, indicating that these parameters had a strong negative and substantial association with one another.

**Figure 5.** Biplot for the first two principal components (PC1 and PC2) was shown using the principal component analysis (PCA) with all measured parameters and 7 varieties.

Under the low-temperature stress, the varieties Y49 and M33 were clustered together on the right side of the biplot with positive loading, and these two varieties were considered for low-temperature tolerance potential. The varieties Y38, T8, and Y1 were clustered together in the direction of MDA and H2O2 to the upper area of the biplot, and relatively poor performance of different enzymatic and non-enzymatic antioxidants activities indicated increased susceptibility to low-temperature stress. Whereas the varieties W57 and M18 shifted to the lower portion and were classified as intermediate to cold stress.
