PHYTOSOCIOLOGICAL SURVEY AND ALLELOPATHIC EFFECTS OF PARHENIUM WEED IN COMPARISON TO OTHER WEEDS IN PAKISTAN

Parthenium weed (Parthenium hysterophorus L.) is an alien invasive weed of neotropical origin
spreading rapidly in Punjab and North West frontier provinces of Pakistan. The present study was
carried out to investigate the distribution of parthenium and its allelopathic effects against maize
in comparison to native associated asteraceous weed species growing in wastelands district of
Lahore. Survey revealed that parthenium weed is becoming a dominant part of local wasteland
flora with the highest values of relative density and frequency as compare to other asteraceous
weeds. Different concentrations of selected weed extracts failed to decline the germination of
maize except higher (15%) concentration of S. arvensis that resulted in reduction of 28% in
germination rate as compared to the control. Data recorded on shoot length of maize reflected
that the lower concentrations of C. arvense significantly suppressed the shoot length and biomass
of maize. Shoot biomass of maize was again significantly reduced even at lower concentrations
of A. conyzoides and C. arvense. Interestingly, Inula sp. extracts at all test concentrations resulted
in an increased biomass of maize. Root length and biomass appeared to be most sensitive part of
maize and retarded significantly in response to different concentrations of extracts of all the test
species except for Inula sp.