Screening parthenium weed (Parthenium hysterophorus L.) seedlings for their allelopathic potential

A laboratory bioassay called ‘the relay seeding technique’ was adapted to detect the presence of growth-altering allelopathic chemicals coming from parthenium weed (Parthenium hysteropohrus L.) seedlings and to determine their effects upon the growth of a number of grass and broadleaf species. The results showed a species-specific response, with either increased or decreased root or shoot length when these other species were grown with parthenium weed seedlings. In the case of curly windmill grass (Enteropogon acicularis L.) and buffel grass (Cenchrus ciliaris L.) there was a tendency to reduce the root length when they were grown with parthenium weed. On the other hand, Rhodes grass (Chloris gayana L.) seedlings promoted root elongation when grown with parthenium weed. Preliminary results suggest that parthenium weed seedlings might be capable of interfering with the growth of certain species even at the very early stages of growth and this would contribute to its invasive capacity.