Abstract:
Wheat is one of the most important food security crops which is cultivated from small to
large scale farms in Ethiopia. However, its productivity has been limited due to various
abiotic and biotic factors including weeds. The aim of the study was to investigate the effects
of seed rates and post emergence herbicides application on weed management and
productivity of wheat. Factorial combinations of three levels of seed rates (100,150 and 200
kg ha-1)and four types of herbicides (Agro 2,4-D 720 g/L 1lt ha-1,Pallas 45 OD 0.5lt ha-
1,Derby 175 SC 100ml ha-1 and Lancolet 450 WG 33 gm ha-1)along with control (a weedy
check) were laid out in RCBD with three replications. A total of identified 12 weed species
were recorded (86 % broad and 14 % grass weeds). Results also revealed that significant
effects of seed rate by herbicide interaction for all the traits studied. The minimum weed
densities (4.52m-2 and 2.7m-2) at 25 and 45 days after planting (DAP), dry biomass of grass
weeds (33.33 kg ha-1) and the highest weed control efficiency (81.22%) were recorded from
the interaction effects of 150 seed rate with pallas 45 OD while the minimum dry biomass of
broad leaf weeds (53.33 kg ha-1) was recorded at 200 kg ha-1 seed rate with lancolet 450
Wettable Granule (WG). The highest number of productive tillers(133.33m-2),seeds per
spike(76.48), thousand grain weight (44.36g),grain yield (4516.42kgha-1)and biological
yield(13100kg ha-1) were recorded from the combination of 150 kg ha-1 seed rate with Pallas
45 OD while the lowest values were observed from the weedy check .Grain yield had strong
positive correlations with each of the yield components, however it was negatively correlated
with dry weed biomass. Based on partial budget analysis, the maximum net benefit was
obtained from the interaction of 150 kg ha-1seed rate with pallas 45 OD but higher number of
marginal rate of return was calculated from 150 kg ha-1seed rate with 2,4-D . It was also
observed that, the combined use of seed rate 150 kg ha-1with Pallas 45 OD effectively
managed weeds, economical and gave maximum yields, which could be recommended for the
test environment. Since the experiment was conducted in one location and for a single season,
it should be repeated over seasons or multi locations for best recommendation.
