Field evidence of the allelopathic properties of Dicranopteris linearis

This study investigates the suspected allelopathic influence of Dicranopteris linearis on the densities of five Malaysian common broad-leaved weeds ( Asystasia gangetica , Melastoma malabathricum , Ageratum conyzoides , Mimosa pudica , and Crassocephalum crepidioides ) and on five Malaysian common grasses ( Echinochloa colona , Eleusine indica , Paspalum conjugatum , Dactyloctenium aegyptium , and Chloris barbata ). The allelopathic effect of D. linearis- infested soil on the emergence and growth of these weed species also was tested. The results reveal that D. linearis strongly reduced the weed density in its vicinity. Ageratum conyzoides and E. colona, the most sensitive weed species, were not found in the D. linearis- infested area. In the greenhouse study, the D. linearis- infested soil also highly inhibited the emergence and growth of the bioassay species. The I₅₀ of the bioassay seeds was reached when the ratio of the infested soil (IS) to uninfested soil (UIS) was 99.55:0.45%. The I₅₀ for the fresh weight of the bioassay seedlings was 81.27:18.73%. For the height of the bioassay seedlings, the I₅₀ was 90.40:9.60%. In this study, there was no obvious difference in the physicochemical properties between the IS and the UIS soils. However, the levels of water-soluble phenolic compounds in the IS were significantly higher than those in the UIS. Dicranopteris linearis might exert its allelopathic influence on weed density, emergence, and growth via its secretion of these phenolic compounds into the soil.