Abstract:
Oil palm residues have been widely used as mulching materials for production of vegetables. Palm oil mill effluent (POME) and oil palm fronds (OPF) were reported to contain allelochemical compounds that suppress growth of seedlings. Therefore, a study was conducted to determine the phytotoxicity effects of different types of oil palm wastes [chopped oil palm trunks (OPT), empty fruit bunches (EFB), palm pressed mesocarp fibre (PPMF) andOPF], by conducting seedling bioassay and seed germination tests on four selected vegetable species, lettuce (Lactuca sativa), tomato (Solanum lycopersicum), cucumber (Cucumis sativus) and green amaranth (Amaranthus viridis). The application of OPF aqueous extract gave the highest reduction in radicle length for the lettuce, tomato, cucumber and green amaranth seedlings. Also, PPMF and EFB extracts reduced radicle length significantly compared to OPT extract. However, the OPT aqueous extract showed no inhibition in radicle and hypocotyl growth, fresh and dry weights, total seed germination percentage and mean germination time for all seedlings. These results indicated that OPT did not release any phytotoxic compounds while OPF released phytotoxic compounds and the degree of inhibitions were higher compared with other wastes. Meanwhile, PPMF also inhibited seedling growth, with greater inhibition compared with the EFB and OPT extracts. |
