The phytotoxic activity of Parthenium hysterophorus L. seedlings on a range of pasture species

Abstract

The optimised plant-box bioassay technique was used to investigate the phytotoxic activity of parthenium weed (Parthenium hysterophorus L.) seedlings on the growth of lettuce (control) and other agriculturally important pasture seedlings. The suppression of seedling growth was greater for native pasture species than for the introduced species. Lettuce seedling growth exhibited different levels of sensitivity to seedlings from different biotypes of parthenium weed coming from its native and introduced range. Two biotypes from the native range (USA and Argentina) gave a stronger suppression than another (Mexico) and all biotypes tested from the introduced range (Australia, China and Vietnam). In addition, there was no significant difference found between two Australian biotypes. The phytotoxic capacity of parthenium weed seedlings was positioned into the lower end of a range of other known phytotoxic species with higher and lower levels of phytotoxic activity. This indicates that parthenium weed may not a very strong phytotoxic species.