Principal component analysis (PCA) biplot of studied parameters grouped by variants of experiment. C, control, non-infested trees; NI, leaves from non-infested branches of infested trees; LI, leaves from branches with 1–2 mistletoe bushes (low degree of infestation); HI, leaves from branches with 5–7 mistletoe bushes (high degree of infestation). RWC, relative water content; Chl a, chlorophyll a; Chl b, chlorophyll b; Chl a/b, chlorophyll a/b ratio; EL, electrolyte leakage; MDA, malondialdehyde; Pro, proline; GSH, glutathione; GSSG, oxidized glutathione; AsA, ascorbic acid; DHA, dehydroascorbic acid; DKGA, 2,3-diketogulonic acid; TPC, total phenolic compounds; SOD, superoxide dismutase; CAT, catalase; APX, ascorbate peroxidase; MDAR, monodehydroascorbate reductase; DHAR, dehydroascorbate reductase; GPX, glutathione peroxidase; GR, glutathione reductase; POD, peroxidase.