KEHINDE J. K.
Abstract
The effectiveness of some weed control methods and seed rate
at controlling weeds and enhancing the yield and yield components of upland
rice cv. FARO 49 (ITA 315) was determined during the wet seasons of 1996 and
1997 at Badeggi in the southern guinea savanna zone of Nigeria. Seeds of FARO
49 at four rates (45, 60, 75kg and 90kg.ha']) in 1996 and three rates (45, 60
and 75kg.ha']) in 1997 were established by drilling at 25cm interrow spacing.
To each of the seed rates different weed control methods were imposed {weeding
once at 30 days after seeding (d.a.s.), weeding twice at 14 and 40 d.a.s., pre-emergence
application of oxadiazon at 0.65kg a.i.ha'1 followed by Basagran PL2 (bentazon
+ propanil) at 1.5kg a.i. ha'1 30 d.a.s., post-emergence application of Basagran
PL2 at 2.5kg a.i.ha~J and weedy check). Application of one form of weed control
or the other resulted in a higher weed suppression, weed control efficiency,
tiller production, number of filled grains per panicle, grain yield and lower
weed coverage than the weedy check. Increasing the seed rate from 45 to 90kg.
ha 'J slightly decreased the weed dry matter weight and increased the grain
yield. In 1997, there were negative but significant correlations between the
yield and weed dry matter at maturity (r= -0.709**), yield and weed coverage
(r=-0.792**). Interaction effects of weed control methods and seed rate on the
dry weed weight at 60 d.a.s. and grain yield was significant. Irrespective of
the seed rate used, the weed dry weight was lowest and grain yield the highest
when herbicides were applied sequentially or two weedings were done. Though
controlling weeds with the sequential herbicide application was the most expensive
method, it had the highest net returns.
Key Words:
bentazon plus propanil, handweeding, herbicide, sequential application, upland
rice and weed control.