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ŠUMARSKI LIST 7-8/2023 str. 68     <-- 68 -->        PDF

triplicates and tested by two-way analysis of variance (ANOVA) followed by comparison of the mean values by Duncan’s multiple range post-hoc test for p<0.05. In two-way ANOVA, phenological variety and physiological status were used as dependent variables, which were interpreted using the Fisher (F) test and their statistical significance levels (p). The R environment was used for all statistical data processing (R Core Team, 2013). The “rstatix” R package (Kassambara, 2020) was used to calculate descriptive statistics and run two-way ANOVA, “ggfortify” for PCA analyzes and “corrplot” for correlation matrix of Pearson’s correlations. Finally, “ggplot2” R package was used for other data visual representations.
Obtained results of biochemical parameters showed that leaves from late oak trees had higher protein and phenolic compounds contents than early oak trees, regardless of the physiological group (vital or damaged) (Table 2). Moreover, for the sake of better presentation of the results from Table 2, we have presented them graphically (Figure 1 and 2). PLOD and PLOV leaves had the highest, while PEOV and PEOD leaves had the lowest content of total flavonoids (Table 2).
As for radical scavenging capacity tests, all tested leaves had low scavenging capacity. ABTS- and NO- radical scavenger tests showed lower than 50% scavenging for all samples, while DPPH-test showed insignificantly higher than 50% scavenging for PEOS, PEOV, PLOV leaves (56.15%, 57.28% and 51.58%, respectively) and 41.69% for PLOD leaves. Late oak leaves had higher ferric reducing antioxidant power (203.5 and 180.4 mg TE/g FW, respectively) than early ones (93.9 and 85.5 mg TE/g FW, respectively), regardless of the physiological group (Table 2).
Two-way Anova was performed for phenological varieties [early (var. praecox) vs late (var. tardissima)], physiological groups (vital or damaged) and their interaction as dependent variables, with the aim to determine whether there was an influence of tested dependent variables on the variability of the analyzed parameters. According to obtained results, phenological variety has no influence on protein and DPPH– radical scavenger activity, while physiological group has no influence on total phenolics content and subsequently on FRAP, ABTS- and NO-