Phytotoxic potential of powder and methanol extract
of
Tinospora crispa (L.) Hook. f. & Thomson leaves as
pre- and post-emergence applications on the growth of
transplanted rice (
Oryza sativa
L.) and associated weeds
were evaluated under glasshouse and field conditions to
determine its herbicidal activity as soil additive material
in rice fields. In glasshouse study, utilization of leaf
powder and leaf extract of
T. crispa as pre-emergence
application provided a satisfactory weed control, inhibiting
seed germination and reducing the growth of germinated
seedlings with an increase in the yield of transplanted
rice. The magnitude of the phytotoxic effects at the same
concentration levels in the test plants was dependent on
the application methods (powder and extract), time of
application (pre-and post-emergence), concentration and
the recipient species. Field experiment consisted of
T.
crispa leaf powder (1, 2 and 4 t ha
-1), chemical herbicide
(pretilachlor + pyribenzoxim at 1 L ha
-1) as positive
control and a negative control (no treatment). There was
nonsignificant difference between leaf powder-treated plots
(2 and 4 t ha
-1 doses) and plots that received herbicidal
treatment in terms of percentage reduction of emergence
and weed DM. In plots amended with 1, 2 and 4 t ha
-1 leaf
powder, weed dry weight was reduced by nearly 80%, 97%
and 99% and total weed seedling density was inhibited by
73%, 94% and 99%, respectively, compared to untreated
plots. There was a significant promotion on grain yield,
straw dry weight and number of seed per panicle of rice,
when treated with leaf powders and chemical herbicide
compared with negative control. These results suggest
that
T. crispa has a significant phytotoxic activity on the
germination and growth of weed species in rice fields.
