Publicação on-line; 30 ref.; 4 tables; Summary (En)

ABSTRACT
Background: Waste-land weeds present around the fields exert their
allelopathic influence on crops through their leaf leachates and
rhizospheric soils.
Objective: A study was conducted to investigate the phytotoxic action of
four common waste-land weeds Parthenium hysterophorus L.,
Achyranthes aspera L., Lantana camara L. and Withania somnifera L.
through their aqueous extracts and rhizospheric soils against winter crops
Avena sativa L., Cicer arietinum L., Hordeum vulgare L. and Triticum
aestivum L.
Methods: Experiments were conducted in Agronomy laboratory in
College of Agriculture at the University of Sargodha. In first experiment,
5% (w/v) water extract from entire plant of each weed was applied to
germinating seeds of crops whereas in second experiment, crop seeds
were subjected to the rhizospheric soil of each weed for germination test.
Results: Results revealed that aqueous extracts of weeds were
more phyto-inhibitory compared to their rhizospheric soils. Minimum
germination percentage (42.5%), germination index (7.4), seedling vigor
index (665.3), root length (3.27 cm), seedling length (14.15 cm) and
seedling biomass (74.2 mg) of crops were recorded in response to
aqueous extract of P. hysterophorus. Root growth of the crops was
affected more compared to the shoot growth. Minimum germination
percentage was observed in A. sativa (13.3) by the action of L. camara
aqueous extract. Rhizospheric soil of L. camara and P. hysterophorus
resulted in minimum germination percentages (57.5 and 58.3,
respectively) and seedling vigor indices (1472.5 and 2008.4, respectively)
of crops. The lowest germination (30%) and germination index (3.7) was
observed for T. aestivum seeds germinated in the rhizospheric soil of
W. somnifera. Among crops, A. sativa and C. arietinum were more
susceptible to the aqueous extracts whereas T. aestivum to rhizospheric
soils of weeds.
Conclusions: It can be concluded that waste-land weeds especially
P. hysterophorus and L. camara negatively affect the crops by their
allelopathy.

Keywords:
allelopathy
aqueous extracts
germination
rhizospheric soil
waste-land weeds
winter crops.