Antifungal properties and phytotoxicity of zinc oxide and lignin nanoparticles

• Main Author: Alvin Swee Ong, Tang
• Format: Thesis
• Language: English; English
• Published: Taylor & Francis Group 2023
• Subjects: S Agriculture (General)
• Online Access: http://ir.unimas.my/id/eprint/46053/

The negative impact created by using agrofungicide in agriculture had led to search for safe alternatives to replace agrofungicide such as nanomaterials. Nanotechnology had been studied in the past decade and several nanomaterials had been reported to have antifungal properties. Thus, this study was done to investigate the effect of two sizes of zinc oxide nanoparticles (ZnO NPs) (~20nm and ~40nm) and lignin nanoparticles (LNPs) (~300nm) against eight selected crop pathogenic fungi viz. five isolates of Pyricularia oryzae (P. oryzae), Colletotrichum musae (C. musae), Colletotrichum truncatum (C. truncatum) and Fusarium oxysporum (F. oxysporum). The antifungal effect of ZnO NPs and LNPs towards tested pathogenic fungi increased along with the increase of nanoparticles concentrations. Isolate dependency of antifungal effect against isolates of P. oryzae was observed for ZnO NPs and LNPs. The ZnO NPs and LNPs significantly inhibited the spore germination of P. oryzae isolates(POK 9 and POSA 2) tested. ZnO NPs were observed to reduce the disease development on rice detached leaf tests. However, ZnO NPs and LNPs may cause phytotoxicity to plants. This led to another objective of this study, to investigate the phytotoxicity of ZnO NPs and LNPs towards nine Sarawak rice landraces. Both sizes of ZnO NPs were not affecting seed germination rate, however, they did affect the shoot and root development. LNPs affect the seed germination rate, shoot and root development. The effect varies at different treatment concentrations of ZnO NPs and LNPs. Landrace/genotype dependent phytotoxicity effect of ZnO NPs and LNPs was observed. As conclusion, this study demonstrated that ZnO NPs and LNPs had antifungal properties against tested pathogenic fungi, but also caused phytotoxicity towards the Sarawak rice landraces. In order to reduce phytotoxicity, foliar application might be considered as ZnO NPs showed suppression to disease development on detached-leaf assay inoculated with P. oryzae (POK 9) spores. For LNPs, it showed no effect to disease development suppression on detached leaf inoculated with POK 9 spores, where the result is similar to antifungal assay. It is suggested a further study on detached-leaf assay could be conducted with other spores of P. oryzae isolates to confirm the antifungal effect of LNPs.