Chemical Weed Control in Grain Sorghum (Sorghum bicolor L.)

Abstract

A field experiment was conducted at the Demonstration Farm
of the Faculty of Agriculture, University of Khartoum, Sudan, during
2012/2013 and 2013/2014 seasons, to determine the magnitude of growth
and yield losses in grain sorghum crop due to weed competition, and to
evaluate the effects of three herbicides viz, sorgoprim, gesaprim and tank
mixture of 2,4-D and gesaprim at three rates of each in addition to a
weed-free and a weed- infested treatments i.e. eleven treatments. The
experiment was laid out in a randomized complete block design with four
replications. The results showed that when the weeds were left to compete
with the sorghum crop throughout the season, the reduction percentages in
the seedlings’ dry weight, plant height and plant shoot dry weight in
2012/13 were 55.4, 39,2 and 47.2 respectively; reductions in the same
parameters were 74.4, 39.1 and 45.4 respectively in 2013/14. Untreated
weeds – infested control, coupled with weed index (WI) of 65%–66%,
inflicted considerable reductions in crop grain number/ plant of 60.1% in
2012/13 and 61.4% in 2013/14, grain weight/plant of 66.3% in 2012/13
and 66% in 202013/14 and on yield( ton/ha) by 65% in 2012/13 and by
66% in 2013/14. All herbicide treatments irrespective of rate of
application, resulted in a good to excellent weed suppression. Herbicides
weed control efficiency (WCE) for 2012/13 and 2013/14 ranged from
56% to 99% for broad-leaved weeds and from 39% to 97% for grassy
weeds. The mixture tank of 2, 4-D + gesaprim @ 0.76L/ha + 0.6 Kg/ha
treated sorghum reduced the WI to 2.5% in 2012/13 and to 3.2% in
2013/14 and resulted in values of crop grains number/plant, grains weight/
plant and yield significantly comparable to weed-free treatment.