STUDIES ON WEED COMPETITION AND PERFORMANCE OF VARIOUS HERBICIDES UNDER DIFFERENT SOWING DATES AND NITROGEN LEVELS IN RAINFED COTTON (Gossypium hirsutum L.)
STUDIES ON WEED COMPETITION AND PERFORMANCE OF VARIOUS HERBICIDES UNDER DIFFERENT SOWING DATES AND NITROGEN LEVELS IN RAINFED COTTON (Gossypium hirsutum L.)
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Date
1983-05
Authors
DADARI, Salihu Adamu
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Abstract
Two field experiments were carried out at the University
Farm, Samaru, Zaria, in the northern guinea savanna zone
during 1981 wet season. Experiment I referred as "weed
competition study" consisted of two main plot treatments
of sowing time (June-sowing and July-sowing) and 12 subplot
treatments of duration of weed competition, among which
six consisted of weed-free period of two weeks interval up
to harvest and six of weed-infested period of two weeks
interval up to harvest. Nitrogen at the rate of 30 kg N
ha was applied by side dressing to the cotton crop at
three weeks after sowing. Experiment II named as "weed
control study", consisted of two treatments of June and
July-sown cotton superimposed with three treatments of 0,
30 and 60 kg N ha and thereby constituting six main-plot
treatments; and six sub-plot treatments of weed control
v/here four treatments of herbicide mixtures of fluridone
plus diuron @ 0.4+0.4 and 0.8+0.8 kg a.i. and norflurazon
plus diuron @ 0.4+ 0.4 and 0.8 + 0.8 kg a.i. ha-1 were
compared with hoe-weeding and unweeded check. All herbicide
treatments were applied pre-emergence, one day after
sowing.
Cotton sown on 29 June and 21 July, 1981 (referred as
June-sown and July-sown crop). Spray application of
"Cymbush" to the cotton crop at the rate of 2.5 1 ha to
control insect-pests, was made from 10 weeks to 16 weeks
after sowing. Manual picking of the seed-cotton started
at 22 weeks after sowing, and continued for five weeks.
June-sown cotton outyielded that sown in July by 48
per cent in weed competition study. The most critical
period of weed competition was four to six weeks after
sowing in June-sown and two to six weeks in July-sown
cotton. Weed dry matter production had a negative correlation
co-efficient with growth, yield and yield components
of cotton. In weed control studies seed cotton yield was
not significantly affected by time of sowing. Cotton crop
responded well to 60 kg N ha -1 in June-sown crop and to
30 kg N ha to July-sown crop. The most promising
herbicide treatment was fluridone plus diuron at 0.8 + 0.8
kg a.i. ha-1 . At 60 kg N ha-1 an increased susceptibility
of weeds to fluridone plus diuron at 0.8+ i.8 kg a.i. ha
was observed as judged by a drastic reduction in weed dry
matter. Fluridone plus diuron at high rate (0.8 + t.8 kg
a.i, ha ) in June-sown cotton under 30 and 60 kg N ha
was the best herbicide ond'was- similarly effective under
60 kg N ha in July-sown crop.
Description
A thesis submitted to the Faculty of Agriculture
of Ahmadu Bello University in partial fulfillment
of the requirements for the degree of Master of
Science in Agronomy
DEPARTMENT faculty of Agriculture &
Institute for Agricultural Research
AHMADU BELLO UNIVERSITY, ZARIA,
NIGERIA
MAY, 1983
Keywords
STUDIES,, WEED,, COMPETITION,, PERFORMANCE,, VARIOUS,, HERBICIDES,, DIFFERENT,, SOWING,, DATES,, NITROGEN,, LEVELS,, RAINFED,, COTTON,, (Gossypium hirsutum L.)