one-way anova
Table 3.1 shows the results from a one-way ANOVA analysis, which was conducted to determine whether there is a significant difference between the sample means. The ANOVA is also known as an ‘analysis of dependencies’, as it is utilized for assuming the cause-and-effect relationship between variables (Statistics Solutions, n.d.). To discern whether the researchers must reject or fail to reject the null hypothesis, the group must compare the significance level (α) with the p-value (Sig.) (van den Berg, n.d.). A p-value less than or equal to the significance level means the researchers must reject the null hypothesis, which means the outcome is statistically significant; otherwise, they should fail to reject the null (Hartmann et. al, 2018). Moreover, according to Beers (2023), the p-value and the statistical significance are inversely proportional — the lesser the p-value, the greater the statistical significance.
Based on Table 3.1, a p-value of 0.052 less than the significance level (0.05) indicates a statistically significant result between the three groups, and that the null hypothesis must be rejected. Therefore, the results show that there is a significant difference in the copper (II) absorbed by the P. hederaceum from the synthetic wastewater within 24 hours, 6 days, 9 days, and 15 days. The findings from the one-way ANOVA test suggest that P. hederaceum is a plant capable of removing copper from wastewater. However, given that the resulting p-value (0.05) is equal to the significance level (0.05), it may not be as effective as other studies on plants that are able to achieve a lower p-value.
Although there is a lack of literature with regard to the absorption of P. hederaceum of pollutants through rhizofiltration, most studies on P. hederaceum provide evidence of its capabilities in air phytoremediation. According to the study of Suárez-Cáceres and Pérez-Urrestarazu (2021), P. hederaceum has shown its ability to reduce VOCs — namely n-hexane and formaldehyde, and more efficiently removing the latter. Another study conducted by Bandehali et. al (2021) further solidifies this, as the researchers observed that Philodendron showed effective removal of the VOC, formaldehyde.
Despite the statistical significance observed in the study, P. hederaceum cannot be categorized as a metal hyperaccumulator, as plants that are identified as such must have shown the potential to accumulate 1000 mg/kg (or 1000 pm) of copper (Sytar et al., 2020). The highest concentration that the P. hederaceum absorbed in the study was 13.6134 ppm.
Tukey HSD Post-Hoc Test
Post-hoc tests are utilized to determine the significant differences between the means of the pairs or groups (bioSTATS, n.d.). The null hypothesis was rejected in the one-way ANOVA, which states that there is a significant difference between the samples. In order to distinguish which group means are significantly different from other group means, Tukey’s HSD test was executed. Table 3.2 shows the pairwise comparisons of the samples’ means to investigate where exactly the differences may lie. 24 hours and 15 days have a p-value equal to 0.036, which is lower than the significance level (0.05), which indicates that there is a significant difference between the heavy metal absorbed by P. hederaceum in 24 hours and 15 days, thus signifying that the copper intake of P. hederaceum is substantially greater in 15 days than in 24 hours, with a mean difference of 7.84, which is considered to be the highest difference in the table. However, there were no significant differences found in the other groups that had a p-value greater than 0.05.