Jee, Wei Ren (2017) The effectiveness of selected phenolic acids against ganoderma boninense and its effects to soil microbial community. Masters thesis, Universiti Malaysia Sabah.
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Abstract
Basal Stem Rot (BSR) disease caused by Ganoderma boninense is thriving rapidly within oil palm plantations, especially in Indonesia and Malaysia. This study illustrates the potential of combination of three phenolic acids at the ratio of 1:1:1 (w/w); caffeic acid (CA), syringic acid (SA) and 4-hydroxybenzoic acid (4-HBA) in suppressing G. boninense colonization and its effect to soil microbial community. There were four objectives being carried out in this master’s thesis. The first objective is to evaluate the in vitro antifungal activity of phenolic acids against Ganoderma boninense and possible development of resistance. Cell assay plates with different concentrations of phenolic acids combination; 0.0, 0.1 mg, 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg and 2.5 mg mL-1 were prepared by incorporating the respective phenolic acids into Potato Dextrose Agar (PDA). For antifungal assays, the growth of G. boninense was inhibited as the concentration of phenolic acids increased. G. boninense in 0.1 to 0.3 mg mL-1 concentrations of phenolic acids was able to reach the maximum growth as in the control plates at the end of the experiment. Phenolic acids with concentrations of 0.4 and 0.5 mg mL-1 gave a significant slower growth rate of the pathogen compared to control, thus G. boninense was unable to reach the maximum growth as controls after 14 days of incubation. The highest concentration of phenolic acids (2.5 mg mL-1) had inhibited the growth of G. boninense completely. While for the study on possible resistance of G. boninense to phenolic acids, G. boninense was transferred to new cell assay plates containing higher concentration of phenolic acids than the previous cell assay plates. The results showed that G. boninense was incapable to develop resistance to higher concentrations of phenolic acids (0.5 and 2.5 mg mL-1). Throughout the incubation period where G. boninense was cultured in cell assay plates containing phenolic acids, there were colour changes occurred to the culture and media itself which indicated the process of phenolic acids degradation. The colour intensity of culture was changed from light brown to dark brown when the concentration of phenolic acids increased. The second objective is to observe the in planta antifungal activity of phenolic acids against Ganoderma boninense through Scanning Electron Microscope (SEM) examination. The Scanning Electron Microscope (SEM) examination and in vitro bioassay showed that the phenolic acids reduced the branching of mycelium and affected the growth of G. boninense mycelium. When the infected oil palm seedling was treated with the phenolic acids, the roots of oil palm seedling showed a reduction in disease symptoms, such as the obstruction on xylem bundles and vessels. The third objective is to quantify the ergosterol content (fungal biomass) of Ganoderma-infected oil palm trees after treated with phenolic acids. There were four concentrations of phenolic acids combination being tested in this study, which were 1.0, 2.0, 3.0 and 4.0 g. All concentrations were capable to suppress the colonization of Ganoderma in infected oil palm trees. However, the concentration 4.0 g was the most effective in suppressing Ganoderma ergosterol, the fungal sterol in infected tissues. Ganoderma Selective Media (GSM) was used to further confirm the presence of Ganoderma besides extraction of ergosterol from the infected tissues. Ganoderma was successfully isolated on GSM after one week of incubation from all infected tissues. The last objective is to investigate the effect of phenolic acids to soil microbial community. Positive changes were observed in the composition of the soil microbes after the application of phenolic acids although it was a slightly increase. The application of phenolic acids into the soil had introduced the presence of some beneficial microorganisms. Besides, the application of phenolic acids did not cause an adverse effect on the microorganism communities in soil. This study showed that the combination of three phenolic acids; caffeic acid, syringic acid and 4- hydroxybenzoic acid at the ratio 1:1:1 (w/w) provided a promising result in suppressing the colonization of G. boninense under different environmental circumstances. Therefore, the combination of phenolic acids could be a potential fungicide to suppress the colonization of G. boninense in oil palm plantation in near future.
| Item Type: | Thesis (Masters) |
|---|---|
| Keyword: | Basal Stem Rot, Ganoderma boninense, Phenolic acids, Syringic acid, Caffeic acid, 4-hydroxybenzoic acid |
| Subjects: | S Agriculture > SB Plant culture > SB1-1110 Plant culture |
| Department: | FACULTY > Faculty of Science and Natural Resources |
| Depositing User: | DG MASNIAH AHMAD - |
| Date Deposited: | 17 Mar 2025 10:57 |
| Last Modified: | 17 Mar 2025 10:57 |
| URI: | https://eprints.ums.edu.my/id/eprint/43191 |
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