SSR Inst. Int. J. Life Sci., 6(4):
2601-2611,
July 2020
Maize Yield
Affected by Periods of Weed Interference in Southern Guinea Savannah Zone of
Nigeria
Tanimu MU1*, Adeosun JO2, Muhammad
A1, Na Allah MS1, Bubuche TS1, Ardo AM3,
Yusuf H4, Tiamiyu RA5
1Faculty of Agriculture, Department of Crop Science, Kebbi State
University of Science & Technology, Aliero, Kebbi State Nigeria
2Faculty of Agriculture, Department of Crop Science, Federal
University Dutsin-ma Katsina State, Nigeria
3Department of Forestry, College of Agriculture Zuru, Kebbi State,
Nigeria
4Lecturer II, Department of Preliminary Studies, College of Science
and Technology, Waziri Umaru Federal Polytechnic, Birnin Kebbi, Kebbi State,
Nigeria
5Department of Crop Science,
Faculty of Agriculture, Usmanu Dan Fodiyo University Sokoto Sokoto State,
Nigeria
*Address for Correspondence: Tanimu Musa Umar, Lecturer 1, Department of Crop
Science, Faculty of Agriculture, Kebbi State University of Science and
Technology, Aliero, Nigeria
E-mail: musa.umartanimu@ksusta.edu.ng
ABSTRACT- Background: Maize is an important
crop for resource poor farmers across Africa and Asia. The crop is susceptible
to weeds that severely reduce yields, because of their competition with the
crop for moisture, nutrients, sunlight and space.
Methods: A regression analysis
was carried out to find the association between maize grain yields and weed dry
matter production. The predicted values of total maize grain yield and weed dry
matter production was obtained using the equation Y= a + b1 z + b2
z2, Y is maize grain yield/weed dry matter production and z is
a function of time of weeding such that the slope is zero at z=0 (time of
sowing) and z2= 12 (time of final harvest) b2 is the
regression coefficients.
Results: The result showed rapid
growth of weeds between 3 and 6 WAS, while the initial period of weed
competition with improved maize varieties lies between 3 and 6 WAS. The crops
kept weed free initially for 20 and 42 days after sowing had yield reduction of
about 65 and 50%, respectively. Plots infested for 63 and 84 days had an
estimated yield loss of 88 and 93%. Initial weed infestation for 42, 60 and 91
days after sowing had yield reduction of 20, 30 and 60%.
Conclusion: The most critical
period of weed competition with the crop was between 6 and 9 WAS. Plots weeded
subsequently after initial infestation of 70, 50 and 22 days after sowing had
estimated 10, 20 and 50% reduction of weed growth respectively.
Key
Words: Gidan
Kwano, Maize varieties, Southern Guinea Savannah, Susceptible, Weed
interference
INTRODUCTION- Maize production in Nigeria was
initially restricted mainly to the forest zone but the production has now
expanded to the savannah where it accounts for over 70% of the production in
the country according to Uyovbisere [1]. Higher production of the
crop in the savannah was attributed to more favorable production conditions,
which include solar radiation intensities, lower night temperature and low
incidence of diseases and pests as observed by Kassam et al [2]. Maize is a cereal plant that produces grains
that can be cooked, roasted, fried, ground, pounded or crushed to prepare
various food items like pap, tuwo, gwate, donkunu and a host of others as
reported by Abdurrahman [3]. All these food types are readily
available in various parts of Nigeria among different ethnic groups which are
Hausas, Yorubas, Ibos, Ibiras, Ishas, Binis, Efiks and Yalas etc as reported by
Osagie and Eka [4]. The major weed of maize in Nothern Nigeria is
Striga it has been reported that: “in the Nigerian Savannah weed related yield
losses ranges from 65-92% has been recorded” according to FAO [5].
Striga causes estimated cereal grain losses of up to N1, 050.00 billion as
observed by IITA [6]. This affects the lives of about 300 million
people according to IITA [6]. Other constraints to maize production
in the maize growing areas of sub-Saharan Africa are downy mildew, rust, leaf
spot, and maize streak virus, other pests include insects namely: stem and ear
borers, armyworms, cutworms, grain borers, and rootworms as reported by IITA [6].
Hoeing is the cultural method adopted for weed control in cereals
of which maize is inclusive in the southern guinea savannah zone. Hoeing is
laborious, slow, expensive and only feasible on a smallholding, as observed by
David et al. [7] and
Adeosun [8]. Some weeds especially those that have close resemblance
with the maize crop at the young stage e.g. Andropogon gayanus, however
escape weeding; these will compete with maize seriously and will cause
reduction in yield considerably. Hand weeding using hoe is beneficial to the
maize crop because it tends to improve aeration in the soil environment as
observed by Adeosun [9]. For the hoe weeding to be successful,
proper timing and frequency of weeding are necessary. Weeds pose a problem to
the growth, development and yield of the maize crop. Like in other crops, weeds
compete with maize for sunlight, water, nutrients and space. The extent of the
competition depends on the rate of growth of the weeds, their growth habit,
their density and time at which they start to grow relative to the crop
according to Matthew [10]. The density of weeds, relative to that of
the crop will have an influence on the degree of onset of competition as
reported by Matthew [10]. It is however interesting to note that
most studies on the weed interference in
maize in the guinea savannah zone of Nigeria have not taken into account
the reaction of different varieties to weed competition. The new varieties used
for his study are tall growing (especially the hybrid variety) and drought
resistant, which will enable them to form canopy to suppress the weeds and
escape drought. Hence the need for this study to compare the four maize
varieties and investigate their reaction to different weed competition at
various periods in this ecological (Southern guinea savannah) zone of the
country. The objective of this study was to assess four maize varieties to ten
periods of weed interference and also to assess the susceptibility of the maize
varieties to the effects of weed growth on grain yield.
MATERIALS AND METHODS
Study area- Field trials were conducted
during the raining seasons of 2011 and 2012 at the Research Farm of the Federal
University of Technology Gidan kwano campus Minna (latitude 9° 41' N and
longitude 6° 31' E; 258.5 m above sea level) in the southern Guinea savanna
zone of Nigeria. The climate of Minna is sub-humid with mean annual rainfall of
about 1284 mm and a distinct dry season of about 5 months duration occurring
from November to March. The mean maximum temperature remains high throughout
the year, about 33.5oC particularly in March and June as reported by
Ojanuga [11] in the Southern Guinea Savannah zone in the Niger State
of Nigeria.
Treatments and Experimental design- The
treatments were laid out split plot arrangement in randomized complete block.
These were made into maize varieties (early, extra early and a late maturing or
hybrid) and ten periods of weed interference. One set of the interference
treatment; plots were kept initially weed-free for 3, 6, 9 and 12 weeks after
sowing (WAS) maize and subsequently left un-weeded. In the other set of treatments, plots were
left un-weeded for 3, 6, 9 and 12 WAS but were left weed free until harvest.
Two control treatments were maintained in which one plot weed free, while the
other plot was left weed infested until harvest in both cases. The treatment
consisted of two (2) extra early maize varieties, one early variety and one
hybrid. The maize varieties tested in this study are: (1) Oba 98; (2) SAMMAZ 13
(Extra early variety); (3) EVDT-Y2000 (Early variety); (4) 2008 DTMA-Y(STR)
(Extra early variety).
Cultural practices- The
experimental area was cleared ridged and spaced at 75cm. The field was marked
out into plots and replications using measuring tape. Each split-plot (4 mx3.75
m) 15 m2 had six ridges. Seeds were sown manually at the rate of 3
seeds per hole along the ridges at an intra-rows spacing of 50 cm. The plants
were thinned to 2 plants per stand at ten days after planting. Weeding using
hoe was carried out at 3, 6, 9 and 12 weeks after sowing during the season of
2011 and 2012. Basal application of fertilizer by banding method using NPK
15-15-15 was done at the recommended rate of 120 kgN, 60 kgP and 60 kgK per
hectare. Weed fresh weight (using weighing scale balance) was obtained by
taking weed samples at random using 1 m2 quadrat in each plot at 3,
6, 9 and 12 WAS. The weed samples were cleaned free of soil and oven-dried at
700C to constant weight, and the dry weight was recorded. Crop
growth and yield parameters were taken and recorded according to recommendation
(at 3, 6, 9 and 12 weeks after sowing).
Statistical Analysis- Data collected were subjected to analysis of variance (ANOVA)
using general linear model (GLM) as described by Snedecor and Cochran [12],
and significant means were separated by Duncan’s Multiple Range Test [13].
Regression analysis was also carried
out to determine the association between maize grain yields and cumulative weed
dry matter production of predicted values of maize grain yield as related to
periods of weed interference with the equation Y= a + b1 z +
b2 z2, where Y is maize grain yield/weed dry matter
production and z is a function of time of weeding such that the slope is zero
at z= 0 (time of sowing) and z2 = 12 (time of final harvest) a and b
are the regression coefficients.
RESULTS- There was high weed infestation during 2011 season than 2012 and
conversely, the crops performed better in 2012 than 2011. The most prevalent
grass weeds include Brachiaria deflexa (Schumah),
Digitaria sanguinalli, Rottboellia
cochinchinensis and Andropogon
gayanus. The prevalent broad leaf weeds were Fleura aestuans (Linn.), Commelina
benghalensis (L.), Sida acuta
Polak, Tridax procumbens and Calapogonium muconoides. Cyperus esculentus (L.) and C. rotundus (L.) were the only Sedges
prevalent in the fields. The effect of variety on weed dry matter was only significant in
2012 but not in 2011 (Table 1). During 2011, wet season, the weed biomass was
higher than in 2012. Weed suppression
is shown by weed dry matter; the varieties were not consistent across the two
years of the study. While 2008-DTMAYSTR gave the best weed suppression in 2011,
EDTY-2000 gave the best weed suppression in 2012. The effect of the
period of weed interference on cumulative weed dry matter was significant in
both years (Table 1). Variety X period of weed interference was significant on
cumulative weed dry matter (Table 2) in all initially weed-infested and those
of weed-free plots during the 2011 wet season. The
result of the effect of variety on grain yield was significant only in 2011
(Table 3). Variety 2008-DTMA-YSTR had the highest grain yield in 2011 with a
value of 3.77 t/ha (Table 3) followed by Sammaz-13 (2.71 t/ha), next was EVDT
Y-2000 (2.57 t/ha) and Oba-98 (2.25 t/ha) had the least grain yield value
during the 2011 wet season. Period of weed interference significantly affected
grain yield in both years. The grain yield was decreased as plots were kept
initially weed-infested beyond 3WAS till harvest during 2011 and 2012 wet
seasons. As the plots were initially kept weed-free the grain yield increased
from a minimum value of 1.69 t/ha and 2.73 t/ha for 2011 and 2012 to a maximum value
of 3.87 t/ha and 6.47 t/ha for 2011 and 2012, respectively. Weed infestation for 3WAS did not
significantly affect the grain yield throughout the study. However, infestation
beyond 6WAS drastically reduced the grain yield compared with the initial weed
free periods from 9WAS till harvest. There was no significant interaction
between variety and period of weed inference on grain yield.
Table 1: Effect of Variety and Period of weed-interference on cumulative weed dry
matter production at Gidan Kwano
|
Treatment |
Cumulative weed dry matter (t/ha) |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
2011 |
2012 |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Variety
(V) |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Oba-98 |
1.72 |
0.37b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Sammaz-13 |
1.61 |
0.33b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
EVDT Y- 2000 |
1.47 |
1.58a |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
2008-DTMA YSTR |
1.35 |
0.35b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
SE+ |
0.35 |
0.34 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Period of Weed-interference (W) |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed Infested for 3 WAS |
0.55d |
0.28b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed Infested for 6 WAS |
0.62cd |
0.44b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed Infested for 9 WAS |
3.21a |
0.45b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed Infested for 12 WAS |
3.39a |
0.48b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed Infested till harvest |
3.52a |
3.36a |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed free for
3 WAS |
1.53b |
0.44b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed free for
6 WAS |
1.10ba |
0.39b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed free for
9 WAS |
0.63cd |
0.34b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed free for
12 WAS |
0.42d |
0.25b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Weed free till harvest |
0.40d |
0.18b |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
SE+ |
0.14 |
0.22 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
** |
** |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Interaction (VxW) |
* |
NS |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
WAS= week after sowing. Means followed by the same letter (s) along the column are not
significantly different at 5% level of probability (DMRT) NS =Not significant. *Significance at 5% level of
probability **Significance at
1% level of probability Table 2: Variety X period of weed interference Interaction on cumulative weed
dry matter at Gidan Kwano during 2011 wet season
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
WAS= week after sowing.
Means followed by the same letter (s)
along the column are not significantly different at 5% level of probability
(DMRT)
Table 3: Effect of Variety and Period of weed-
interference on grain yield at Gidan Kwano for 2011 and 2012 wet seasons
|
Treatment |
Grain
yield (t/ha) |
|
|
|
2011 |
2012 |
|
Variety (V) |
||
|
Oba-98 |
2.25b |
4.38 |
|
Sammaz-13 |
2.71b |
3.83 |
|
EVDT-Y2000 |
2.57b |
4.23 |
|
2008DTMA-YSTR |
3.77a |
4.23 |
|
SE+ |
0.21 |
0.25 |
|
Period of weed-interference (W) |
||
|
Weed
Infested for 3 WAS1 |
3.57a |
5.95a2 |
|
Weed
Infested for 6 WAS |
2.51bc |
4.63bc |
|
Weed
Infested for 9 WAS |
2.40bc |
3.93dc |
|
Weed
Infested for 12 WAS |
1.69c |
2.97e |
|
Weed
Infested till harvest |
1.57c |
1.79e |
|
Weed
free for 3 WAS |
1.69c |
2.73de |
|
Weed
free for 6 WAS |
2.00c |
3.53dc |
|
Weed
free for 9 WAS |
3.59a |
4.25bc |
|
Weed
free for 12 WAS |
3.67a |
5.41ab |
|
Weed free till harvest |
3.87a |
6.47a |
|
SE+ |
0.33 |
0.41 |
|
Interaction
(VxW) |
NS |
NS |
1. WAS - week after
sowing
2. Means followed by
the same letter (s) / are not significantly different at 5% level of
probability (DMRT)
3. NS=
non-significant
Regression analysis- Fig. 1 to 4 contained curves of predicted values of maize grain
yields and total weed dry matter production using the equation Y= a + b1z
+ b2z2, where Y= maize grain yield/ weed dry matter
production and z is a function of time of weeding such that slope is zero at t=
0 (time of sowing) and t= 15 (time of final harvest) b2 is
regression coefficient. The reconstituted equation in nonlinear form is Y= a +
b1z + b2z2 according to Salgado [14].
The equation gave a relationship of yield / total weed dry matter production
and weeding time which has zero slope at both t= 0 and t= 15 weeks. In 2011,
the crops kept weed free initially for 20 and 42 days after sowing had yield
reduction of about 65 and 50% respectively. Conversely, plots infested for 63
and 84 days had an estimated yield loss of 88 and 93% (Fig. 1). Weed reduction
of 10, 20, 50 and 80 % were obtained on plots weeded at 94, 86, 60 and 29 days
after sowing respectively (Fig. 2). The most rapid weed growth in 2011 occurred
between 3 and 6WAS. Maize variety Oba-98 was critically affected by weed interference
between 3 and 6WAS (Table 1).
.jpg)
Fig. 1: Fitted values of grain yield (maize) as affected by period of weed
interferencen Gidan kwano 2011
.jpg)
Fig.
2: Fitted values of total weed dry matter production as affected by
period of weed Interference Gidan kwano 2011
In 2012, crops weed free
initially for 91, 84 and 40 days after sowing had yield reduction of 8, 10 and
50% respectively (Fig. 3). Initial weed infestation for 42, 60 and 91 days
after sowing had yield reduction of 20, 30 and 60% respectively (Fig. 3). The
most critical period of weed competition with the crop in 2012 was between 6
and 9 WAS (Fig. 3). On the other hand, plots weeded subsequently after the
initial infestation of 70, 50 and 22 days after sowing had estimated 10, 20 and
50% reduction of weed growth respectively (Fig. 4).
Although the varieties were
on the field for the same period, obvious differences in their growth and
subsequent yields were observed. While hybrid variety Oba-98 was initially
fast-growing than the other three, at the combined analysis, the variety
2008-DTMAYSTR was most vigorous until the harvest of the other three varieties
at the combined analysis. This conformed to the report of Shinggu et al. [15] that showed
similar effects on maize varieties tested.
.jpg)
Fig. 3: Fitted values of grain
yield (maize) as affected by period of weed interference Gidan kwano 2012
.jpg)
Fig.
4: Fitted values of total weed dry matter production as affected by
period of weed
Interference Gidan kwano 2012
DISCUSSION
Performance of Maize Variety and Weed Dry Matter Production- Although the varieties were on the field for the same period,
obvious differences in their growth and subsequent yields were observed. While
hybrid variety Oba-98 was initially fast-growing than the other three, at the
combined analysis, the variety 2008-DTMAYSTR was most vigorous until harvest of
the other three varieties at the combined analysis. This conformed to the
report of Harika and Bains [16] that showed similar effects on maize
varieties tested. The lowest grain yield was obtained with hybrid variety
Oba-98 during 2011 wet season despite its vigorous growth during the later
stage of life-cycle; the grain yields of Sammaz-13 and EVDTY-2000 were similar
but higher than that of Oba-98. The reason for this may be since Sammaz-13 is
early maturing, adequate grain filling occurred before the cessation of
rainfall, which might not be the situation with the-late maturing variety
oba-98, which produced lower grain yield. Oba- 98 was observed to produce
highest cumulative weed dry matter among the other varieties this might be as a
result of the long slender leaves of the variety which cannot form canopy to
smoother weeds to prevent them growing. During 2011 wet season, weed reduction
of 10, 20, 50 and 80% were obtained on plots weeded at 94, 86, 60 and 29 days
after sowing respectively while during 2012 wet season, plots weeded
subsequently after the initial infestation of 70, 50 and 22days after sowing
had estimated 10, 20 and 50% reduction of weed growth respectively. This is
attributed to the longer days taken after infestation before control measure
were applied hence the less weed dry matter reduction was observed as earlier
reported by Travlos [17].
Effect of Period of
Weed Interference on the Performance of Maize- Weed infestation throughout the crop life-cycle decreased the
yield of maize variety Oba-98 by 65 and
50% in 2011. Similar yield reductions between 50 and 87% of maize due to
uncontrolled weeds throughout the crop life-cycle were reported by Usman et al [18]. Period of weed
interference also had a significant effect on crop vigour score at 9WAS during
2012 wet period season. Keeping plots weed free till 9WAS and beyond produced
more vigorous crops, while keeping crops weed infested and beyond similar
periods, produced less vigorous crops. This might be due to the competition for
growth factors between the maize and the weeds in the weed infested plots as
reported by IITA [19] and Ferrero
et al. [20]. Plant height was significantly affected at 9WAS and
at harvest for both years. While keeping plots weed free till 9WAS and beyond
produced taller crops, the converse was the case when plots were weed infested
for the same period. Carson [21] stated that when maize crops were
kept weed infested for 9WAS and beyond, their heights significantly decrease.
Other yield parameters such as maize cob weight, cob length and weight of 100
seeds were all significantly affected by period of weed interference. Weed
infestation from 6WAS and till harvest significantly decreases these yield
parameters. In the study, uncontrolled weeds throughout the life cycle of maize
varieties resulted in grain yield loss of 59.43% and 72.33% respectively for
2011 and 2012 wet seasons compared to maximum obtained with weed free plots throughout
the study. Weed infestation for 3WAS only did not significantly affect grain
yield of maize in 2011 compared with initial weed free plots at 9WAS, while
weed infestation for 3WAS only was comparable to initial weed free plots up to
9WAS. It is apparent that once the crop was kept weed free for 12WAS subsequent
weed infestation until harvest did not cause any significant reduction in maize
grain yield in the four varieties. Contrary to earlier reports, weeds
infestation for the first 3WAS caused a significant reduction in maize grain
yield, even though it did not has an adverse effect on crop growth as reflected
in crop vigour score, crop height and weed dry matter production. The yield
depression by weed infestation for 3WAS may be attributed to rapid weed growth
and its high infestation within 3WAS during the growing season. This was
apparent in the weed cover score at 9WAS and beyond. Weed infestation with crop
until 12WAS resulted in significantly lower crop vigour score and grain yield
compared to infestation for 3WAS. This result agrees with those obtained by
Kunjo [22] and Bakut [23], who has similarly reported
significant maize yield reduction when weeds were associated with the crop for
6 and 8WAS respectively. Subsequent weed removal until 12WAS did not prevent
the reduction in grain yield compared with weed infestation until harvest. Weed
dry matter production was higher during 2011 than in 2012. The result showed
that maximum maize grain yield was obtained from plot kept weed free for both 2011
and 2012 wet seasons. Variety 2008-DTMAYSTR and EVDTY-2000 consistently had a
maximum grain yield during the growing seasons. In 2011 wet season, maize plots
kept weed free initially for 20 and 42 days after sowing had yield reduction of
65 and 50%, respectively. However, during 2012 season, maize kept weed free
initially for 91, 84 and 40 days after sowing, had yield reduction of 8, 10 and
50% respectively. This may be as a result of benefits of utilization of
nutrients underground according to Sohrab and Ali [24]. Result of
this study showed that weed infestation at 3WAS did not affect yield of maize.
This is supported by Sohrab and Ali [24], which showed that weed
infestation untill 3WAS did not affect maize grain yield. Weed infestation for
the first 3 weeks did not have any adverse effect on growth and yield of maize,
provided that weeds are removed subsequently, according to Takim and Fadayomi [25],
who worked on cereal. However, Scott [26] had similarly reported
significant positive correlation between maize grain yield vegetative growths
as well as negative correlation between maize grain yields with weed dry
matter. The result obtained indicated that weed interference untill harvest
reduced grain yield. Nagaragu and Kumar [27] have similarly reported
significant maize yield reduction when weeds were associated with the crop for
6 and 8WAS, respectively. In this study, it was observed in 2011 that period of
21-42 days after sowing is the time when weeds begin to interfere and compete
with crops for growth factors. Hence it is the critical period that the weeds
exert pressure on maize crop.
CONCLUSIONS- Among the varieties tested, 2008-DTMAYSTR consistently had the
highest yield of 3.77 and 4.23t/ha followed by EVDT Y-2000 with yield of 2.57
and 4.23 t/ha, Oba-98 2.25 and 4.38 t/ha and Sammaz-13 2.71 t/ha and 3.83 t/ha
for both growing seasons respectively. During 2011 wet season the critical
period for weed interference is 35 days after sowing and the corresponding weed
dry matter production for this period was 1.80 t/ha while the critical period
that will cause d55significant grain yield is 35 days and the critical grain
yield is 2.10 t/ha. During 2012, wet season however, the critical period for
weed interference is 42 days after sowing and the corresponding weed dry matter
production for this period is 3.90 t/ha; while the critical period that will
cause significant grain yield decrease, when weed infestation is not checked
i.e. 56 days after sowing, while the corresponding critical grain yield for that
period is 4.10 t/ha. Varieties 2008-DTMAYSTR and EVDTY-2000 are recommended for
cultivation in the study area. A weed free period for the first 35-42 days
after sowing is required for optimum grain yield of the improved maize
varieties. The critical period of weed interference with maize is between 3 and
6 WAS.
It is expected that more improved or elite maize varieties, when
managed under good weed control regimes will lead to the production of higher
yield that will be utilized for the teeming population in the study area and
beyond.
ACKNOWLEDGEMENT- The author’s area grateful to the Federal University of Technology
Gidan kwano Minna, Niger state Nigeria
for providing University Teaching and Research Farm and the laboratory which
were utilized during the study period. The authors are very grateful to the
efforts of the authority of Kebbi State University of Science and Technology
Aliero for the support and encouragement.
CONTRIBUTION OF AUTHORS
Research concept- Adeosun JO
Research design- Tanimu MU, Muhammad A
Supervision- Adeosun JO
Materials- Tanimu MU, Bubuche TS
Data collection- Ardo AM, Na-Allah MS
Data analysis and Interpretation- Tanimu MU
Literature search- Tanimu MU
Writing article- Yusuf H, Bubuche TS
Critical review- Adeosun JO
Article editing- Muhammad A, Tiamiyu RA
Final approval- Adeosun JO
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