EFFECTS OF NITROGEN, PERIOD OF WEED INTERFERENCE AND CHEMICAL WEED CONTROL ON OKRA (Abelmoschus e s c u l e n t u s (L.) Moench)
EFFECTS OF NITROGEN, PERIOD OF WEED INTERFERENCE AND CHEMICAL WEED CONTROL ON OKRA (Abelmoschus e s c u l e n t u s (L.) Moench)
No Thumbnail Available
Date
1988-11
Authors
ADEJONWO, KOLAWOLE OWOLABI
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
F i e l d experiments were conducted d u r i n g t h e 1984 and
1985 dry season at Kadawa in t h e Sudan savanna and d u r i n g t he
wet season at Samaru in the n o r t h e r n Guinea Savanna
e c o l o g i c a l zones of N i g e r i a . The aim was to study t h e e f f e c t2
of n i t r o g e n on t h e response of two v a r i e t i e s of okra
(Abelmoschus e s c u l e n t u s (L. ) Moench) to v a r i o u s p e r i o d s of weed
i n t e r f e r e n c e and to i d e n t i f y s u i t a b l e methods i n c l u d i n g t h e use
of h e r b i c i d e s , for s e a s o n - l o n g weed c o n t r o l in t h e crop.
I n the weed i n t e r f e r e n c e experiment, the two okra
v a r i e t i e s , V35 and TAE-38 were s i m i l a r in growth, y i e l d and
i n t h e i r r e s p o n s e s t o n i t r o g e n a p p l i c a t i o n . Variety o f o k ra
had no e f f e c t on weed cover and weed d r y m a t t e r p r o d u c t i on
because of t h e i r s i m i l a r growth p a t t e r n . However, p e r i o d s of
weed i n t e r f e r e n c e s i g n i f i c a n t l y i n f l u e n c e d a l l t h e v a r i a b l es
c o n s i d e r e d i n c l u d i n g f r u i t y i e l d . Keeping t h e crop weed-free
u n t i l 3 weeks a f t e r sowing (WAS) did not prevent d e p r e s s i on
i n growth and y i e l d of okra due to the adverse e f f e c t of
subsequent weed i n f e s t a t i o n . Conversely, weed i n t e r f e r e n ce
u n t i l 3 WAS had no adverse e f f e c t on o k r a p l a n t s . I n f e s t a t i on
u n t i l 6 WAS however d e p r e s s e d the v i g o u r , h e i g h t , leaf number,
shoot dry m a t t e r p r o d u c t i o n , f r u i t number and y i e l d . The crop
was most c r i t i c a l l y a f f e c t e d by weed i n t e r f e r e n c e between 3 and
6 WAS, Crop kept weed-free for 12 WAS and longer had f r u it
y i e l d comparable w i t h t h a t weeded throughout the growth p e r i o d.
I n o r d e r to o b t a i n maximum y i e l d , it was r e q u i r e d to keep the
crop weed-free for a p e r i o d of 12 weeks or more from t h e time
of sowing.
In the herbicide evaluation t r i a l s , the two v a r i e t i es
of okra did not differ significantly in growth and yield.
However, variety TAB-38 contained higher per cent crude
protein but was less viscous than V35. Among the herbicide
treatments, metolachlor plus prometryne at 2.0 + 1.0 kg a . i . / ha
followed by supplementary hoe-weeding (at 6 WAS) was the most
consistent in a l l the t r i a l s in terms of good weed control and
high okra fruit yields that were comparable to three hoe-weedings.
Although directed post-emergenee herbicide treatments
effectively controlled weeds, they were phytotoxic to okra plant
as reflected in depressed crop growth characters and low okra
fruit yields. Significant effect of weed control treatments on
fruit viscosity and per cent crude protein content was also
observed.
In the study, uncontrolled weed growth throughout the
crop life-cycle depressed crop vigour, height, leaf number and
shoot dry matter production. It also reduced okra fruit
yields by 92% and 94% compared with the appropriate best
treatments in the weed interference and chemical weed control
experiments, respectively.
Description
A D i s s e r t a t i o n s u b m i t t e d t o t h e P o s t g r a d u a t e School
Ahmadu Bello U n i v e r s i ty
i n p a r t i a l fulfillment of t h e r e q u i r e m e n t s for t he
d e g r e e of Doctor of Philosophy in Agronomy
DEPARTMENT OF AGRONOMY
FACULTY OF AGRICULTURE
AHMADU BELLO UNIVERSITY
ZARIA, NIGERIA
NOVEMBER, 1988
Keywords
EFFECTS,, NITROGEN,, PERIOD,, WEED,, INTERFERENCE,, CHEMICAL,, WEED,, CONTROL,, OKRA, (Abelmoschus e s c u l e n t u s (L.) Moench).