Abstract:
Weed incursion in cultivated
fields is a serious biological problem, which
causes considerable yield losses of
economically important field crops through
allelopathy and competitive interactions.
Spotted knapweed (Centaurea maculosa)
and yellow melilot (Melilotus officinalis)
are among the most prevalent weeds in
cultivated fields of Pakistan, particularly in
wheat fields. Like many other weeds, they
may pose allelopathic and competitive
challenges to field crops. The objective of
this study was to evaluate allelopathic
potentials of the two weeds on germination
and seedling growth of wheat under
laboratory conditions. Amounts of 15, 20,
25 and 30% concentrated leaf aqueous
extracts of C. maculosa and M. officinalis
were prepared and tested for their effects on
germination percentage, radicle and
coleoptile lengths of wheat. Germination,
radicle and coleoptile lengths of test crop
declined significantly at higher
concentration (25-30%) of the extracts of
two weeds. However, concentration of
M. officinalis up to 20% had either no effect
or stimulatory effects on the studied growth
characteristics of wheat. Highest
germination inhibition and decreased
seedling growth were caused by leaf
extracts of C. maculosa at 30% extract
concentration. Growth inhibition was
generally dependent on the extract
concentration. The study indicated that both
plant exhibited allelopathic activity and
growth inhibitory effects on wheat at higher
concentration; however, extracts of
C. maculosa were more phytoinhibitory than M. officinalis. The weeds could serve
as potent allelopathic plants for
management of other weeds.
