ABSTRACT
Residue of some of herbicides in oil palm cropping systems might have negative effects on some arable crops intercropped within the palm inter-rows.The study determined the residual effect of Indaziflam herbicide on some common arable crops, the relative persistence of varied concentration of Indaziflam in the soil and the effect of applied Indaziflam on weed seed bank. This is with a view to providing information on effecting proper weed management strategies in oil palm cropping systems. The experiments were carried at the greenhouse and field of Nigeria Institute for oil palm (NIFOR) Benin – City Edo State for two years cropping season 2016 and 2017. The experiments were conducted in a completely randomized design in three replicates. Experiment one consisted of Indaziflam concentrations of (0.000 , 0.0045, 0.0090, 0.0135, 0.0180, 0.029, 0.0315, 0.0360, 0.0360, and 0.045 kg a.i ha-1) and five separate times of soil sampling for growing maize, cucumber, melon and tomato. While experiment two consisted of untreated plot as control, glyphosate applied at 1.5 kg a.i ha-1, tank mixture of glyphosate plus diuron at 2.0 kg a.i ha-1+ 1.5kg a.i ha-1, glyphosate followed by Indaziflam ten days later at 1.5kg a.i ha-1+ 0.04 kg a.i ha-1, glyphosate followed by Indaziflam ten days later at 1.5 kg a.i ha-1+0.05 kg a.i ha-1, tank mixture of glyphosate plus Indaziflam at 1.5 kg a.i ha-1+0.04kg a.i ha-1, tank mixture of glyphosate plus Indaziflam at 1.5kg a.i ha-1+0.05kg a.i ha-1, indaziflam at 0.05 kg a.i ha-1 Indaziflam at 0.045kg a.i ha-1as herbicides treated plots and five separate times of soil sampling for growing maize, cucumber, melon and tomato. In the last experiment, soil samples were collected from the herbicides treated plot and placed in screen house for soil seed bank study.The results show that maize, cucumber, melon and tomato dry weight loss decreased as the soil samples time for application of indaziflam increased from 0-4 weeks . Germination of maize, cucumber, melon and tomato increased as the time of soil sampling after herbicide application increased from 0 - 16 weeks. Weed seed emergence was highest in the control plot and higher in glyphosate treated plot, but lower at 0 weeks of soil sampling after herbicide application with weed density of 100 m-2 at 16 weeks of applied herbicides . In plots treated with tank mixture of glyphosate plus diuron, weed seed emergence density was between 5 m-2 and 7 m-2 at 0 weeks of soil sampling and was 100 m-2 and 120m-2 respectively at 16 weeks of soil sampling. In other plots where Indaziflam was tank mixed with glyphosate, used singly or applied ten days after glyphosate treatment had lower weed density up to 16 weeks of soil sampling after herbicide application. In conclusion indaziflam affect the height and dry weight of maize, melon, cucumber, and tomato till 12 weeks after herbicide application. However, the period of 16 weeks has to lapse before intercropping maize, melon, and cucumber in oil palm farm.
TABLE OF CONTENTS
Title Page ii
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables xi
List of Figures xiii
List of Plates xiv
Abstract xv
CHAPTER 1:
INTRODUCTION 1
1.1 Justification of the Study 5
1.2 Objectives of the Study 6
CHAPTER 2:
LITERATURE REVIEW 7
2.1 The Oil Palm 7
2.2 Weed Competition and Management in Oil
Palm 8
2.3 Persistence of Herbicides in Soil 11
2.4 Effect of Herbicides Residues on
Subsequent Crop 12
2.5 Factors Regulating the Persistence of
Herbicide in the Soil 15
2.5.1 Soil characteristics 16
2.5.2 Soil pH 18
2.5.3 Soil microbial decomposition or degradation 19
2.5.4 Chemical decomposition 23
2.5.5 Leaching 23
2.5.6 Plant uptake and metabolim 25
2.5.7 Surface runoff 26
2.6 Environmental Conditions for Herbicides
Persistence 26
2.6.1 Tempreture 27
2.6.2 Photodecomposition 27
2.6.3 Volalization 28
2.7 Herbicidal Characteristics 29
2.8. Residual Herbicides and Weed Control 30
2.9. Adverse Conditions 30
2.10 Biological Assay: Definition and
Implication 31
2.10.1 The benefit of bioassay 32
CHAPTER 3: MATERIALS AND
METHODS 35
3.1 Study Locations 35
3.2 Experiment
1: Evaluation of the Residual
Activity and Persistence of
the Indaziflam in the Soil of
Different Concentrations in the Soil 35
3.2.1 Development
of bioassay techniques for evaluating the residual
activity
of indaziflam 35
3.2.2 Experimental design 37
3.2.3 Data collection 38
3.2.4 Statistical analysis 39
3.3 Experiment
2: Evaluation of the residual effect of indaziflam on
common intercrops following application for weed
control in the
oil
palm crops 39
3.3.1 Experimental design 39
3.3.2 The
field establishment 40
3.3.3 The bioassay trial 41
3.3.4 Data collection and analysis 42
3.3.5 Statistical analysis 43
3.4. Experiment 3: The Effect of Indaziflam on Weed Seed Bank Dynamics 43
CHAPTER 4: RESULTS AND DISCUSSION 45
4.1 Results 45
4.1.1. Edaphic properties of the experimental site
at varying depths 45
4.1.2 Metrological data of the study area at the
Nigerian Institute for
Oil
Palm Research (NIFOR) Benin City, Nigeria in 2016 and 2017 48
4.1.3 Residual effect of indaziflam concentration
on selected test crops
weeks
after storage treatment 48
4.1.3.1
Residual effect of indaziflam concentration weeks after storage
treatment
on height tomato 48
4.1.3.2 Residual effect of indaziflam concentration
weeks after storage
treatment on vine length of cumber seedlings 50
4.1.3.3 Residual effect of indaziflam concentration
weeks after storage
treatment on length of melon seedlings 52
4.1.3.4.
Residual effect of indaziflam concentration in soil weeksafter storage
treatment
on height of maize seedlings 54
4.1.4.1 Predicted loss in maize dry weight due to indaziflam
application rate
in soil weeks
after storage treatment 56
4.1.4.2 Predicted loss in cucumber dry weight due to indaziflam application
rate in soil weeks after storage treatment 58
4.1.4.3 Predicted loss in melon dry
weight due to indaziflam
application rate
in
soil weeks after storage treatment 60
4.1.4.4 Predicted loss in tomato dry weight due to indaziflam
application
rate in soil weeks after storage treatment 62
4.1.5.1 Combined residual effect of applied indaziflam and selected
herbicides
on germination of some
selected test crops weeks after soil application 64
4.1.5.2 Combined residual effect of applied indaziflam and selected
herbicides
on germination of maize 64
4.1.5.3 Combined
residual effect of applied indaziflam and selected herbicides
on germination of melon 66
4.1.5.4 Residual effect
of applied indaziflam and selected
herbicides on
germination of cucumber 68
4.1.5.5 Effect of
indaziflam and selected on mean tomato
germination (%)
in 2016 and 2017 70
4.1.6.1 Residual effect of field applied of indaziflam and selected herbicide
on plant height of some
selected test crops weeks after soil
application
at different depth 72
4.1.6.2 Residual effect of field applied of
indaziflam and selected herbicide
on mean
maize height in 2016 and 2017 at 0 -15
and15-30 cm soil depth 72
4.1.6.3 Residual effect of field applied of
indaziflam and selected herbicide
on melon vine height in 2016 and 2017 at
0 -15 and 15-30cm soil depth 75
4.1.6.4 Residual effect of field applied of
indaziflam and selected herbicide
on
cucumber vine length in 2016 and 2017 at 0
-15 and 15 - 30 cm
soil
depth 77
4.1.6.5 Residual effect of field applied of
indaziflam and selected herbicide on
tomato height in 2016 and 2017 at 0 -15
and 15-30cm soil depth 79
4.1.7.1. Predicted
loss in dry weight of all the test crops due to soil applied
of indaziflam and selected herbicide in 2016 and 2017 at 0 -15
and
cm soil depth 81
4.1.7.2 Loss in
dry weight of maize due to soil application of indaziflam
and selected herbicide in 2016 at
0 -15 and 15-30cm soil depth 81
4.1.7.3 Loss in dry weight of melon due to soil
application of indaziflam
and selected herbicide in
2016 in 0 -15 and 15 - 30 cm soil depth 83
4.1.7.4 Loss in dry weight of cucumber due to soil
application of indaziflam
and selected herbicide
in 2016 0 -15
and 15 - 30 cm soil depth 85
4.1.7.5 Loss in dry weight of tomato due to soil
application of indaziflam
and selected herbicide in
2016 at 0 -15 and 15 - 30 cm soil depth 87
4.1.8.1 Loss in dry weight of maize due to soil
application of indaziflam
and selected herbicide in
2017 at 0 -15 and 15 - 30 cm soil depth 89
4.1.8.2 Loss in
dry weight of melon of due to soil application of indaziflam
and selected herbicide in
2017 at 0 -15 and 15 - 30 cm soil depth 91
4.1.8.3 Loss in
dry weight of cucumber of due to soil application of
indaziflam
and selected herbicide in 2017 at 0 -15 and
15
- 30 cm soil depth 93
4.1.8.4 Loss in dry weight of tomato of due to soil
application of indaziflam
and selected herbicide in
2017 at 0 -15 and 15 - 30 cm soil
depth 95
4.1.9.1 Weed seed population at different treatment 97
4.1.9.2 Number of
viable weed seedling
emergency pattern 97
4.2 Discussion 100
4.2.1 Edaphic and metrological features 100
4.2.2 Residual effect of indaziflam storage time
concentration on tomato,
cucumber, melon and maize growth 100
4.2.3 Predicted loss in maize, cucumber, melon and
tomato due to storage
time and concentration of indaziflam
in soil 101
4.2.4 Residual effect of indaziflam and other
herbicides on maize, melon,
cucumber and tomato germination 101
4.2.5 Residual effect of indaziflam and other
herbicides on the performance
of
maize, melon, cucumber and tomato at
different soil depth 103
4.2.6 Residual effect of indaziflam and other
herbicides on the performance
of
maize, melon, cucumber and tomato at different soil depth 103
4.2.7 Population of weed seed emergence in
herbicides treated soil 104
CHAPTER
5: CONCLUSION AND RECOMMENDATION 105
5.1 Conclusion 105
5.2 Recommendation 106
References 107
Appendix 114
LIST OF TABLES
4.1.1: Physical and
chemical properties of soil at the study site
of the Nigerian Institute
for oil palm research (NIFOR)
Benin city in 2016 and 2017 46
4.1.2: Metrological data of experimental area at the Nigeria
Institute
for Oil palm Research
(NIFOR) Benin city in 2016 and 2017 47
4.1.3: Residual effect
of indaziflam concentration weeks after storage
on height of tomato 49
4.1.4: Residual effect
of indaziflam concentration weeks after storage
on vine length of cucumber seedlings 51
4.1.5: Residual effect
of different concentrations of indaziflam on
melon (cm) seedlings at 0 –
4 weeks after treatment in 2016
and 2017 53
4.1.6: Residual effect
of indaziflam concentration weeks after storage
time on height (cm) of maize 55
4.1.7: Combined
residual effect of applied indaziflam herbicides on
mean maize germination (%)
in 2016 and 2017 65
4.1.8: Combined residual effects of herbicides on mean melon
germination (%) in 2016 and
2017 67
4.1.9: Combined
residual effect of herbicides on mean cucumber
germination (%) in 2016 and 2017 69
4.1.10: Combined
residual effect of indaziflam and some reference
herbicides on mean tomato
germination 71
4.1.11: Residual effect
of field applied of indaziflam and selected
herbicide on mean maize
height in 2016 and 2017 at 0 -15 cm
and 15 -30 depth 74
4.1.12: Residual effect
of field applied of indaziflam and selected
herbicide on melon height in
2016 and 2017 within 0-15 cm depth 76
4.1.13: Residual effect
of applied treatment of indaziflam and
selected
herbicide on cucumber vein
length in 2016 and 2017 at
0 cm -15cm and 15- 30 soil depth 78
4.1.14: Residual effect
of applied of indaziflam and selected herbicide
on tomato height in 2016 and
2017 at depth of 0 – 15cm and
15-30cm soil depth 80
4.1.15: Weed seedbank seedling composition in diffrent herbicides
plot 98
LIST OF FIGURES
4.1.1: Fitted
dry weight of maize seedlings at various storage time
at different herbicide
concentration 57
4.1.2: Fitted
dry weight of cucumber seedlings at various storage time
at different herbicide
concentration 59
4.1.3: Fitted
dry weight of melon seedlings at various storage time
at different herbicide
concentration 61
4.1.4: Fitted
dry weight of tomato seedlings at various storage time
at different herbicide
contraction 63
4.1.5: Fitted
dry weight of maize seedlings at various storage time
at 0-15 cm
and 15- 30 cm at 2016 82
4.1.6: Fitted
dry weight of melon seedlings at various storage time
at 0—15 cm
and 15-30cm at 2016 84
4.1.7: Fitted
dry weight of cucumber seedlings at various storage time
at 0-15 cm
and 15-30cm at 2016 86
4.1.8: Fitted
dry weight of tomato seedlings at various storage time
at 0-15 cm
and 15 – 30cm at 2016 88
4.1.9: Fitted
dry weight of maize seedlings at various storage time
at 0-15 cm
and 15- 30cm at 2017 90
4.1.10: Fitted
dry weight of melon seedlings at various storage time
at 0-15cm and 15-30cm
at 2017 92
4.1.11: Fitted
dry weight of cucumber seedlings at various storage time
at 0-15
cm and 15 -30 cm 2017 94
4.1.12: Fitted
dry weight of tomato seedlings at various storage time
at 0-15 cm
and 15 – 30 cm at 2017 96
4.1.13: Viable
weed seed population at application of different
herbicides 2016 and 2017 99
LIST OF PLATES
4.1.1: Nifor
field 30 experimental site. 114
4.1.2: Tank
mixture of glyphosate plus indaziflam at 4 weeks after
Spraying 115
4.1.3: Effect
of tank mixture of glyphosate +diuron at 16 weeks after
spraying
116
4.1 4: Effect of tank mixture of
glyphosate + indaziflam at 16 weeks
after spraying
117
CHAPTER 1
INTRODUCTION
Oil palm (Elaeis guineensis Jacq.) is
native to tropical Africa and it is an economic crop in Central, South America
and South East Asia. In West Africa oil palm is cultivated along the coasts of
Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Benin, Cameroons and Nigeria
(Corley and Tinker, 2003; Ekhator et al.,
2018). In these countries, oil palm is cultivated to
meet the local and growing industrial demand for palm oil and palm kernel. Oil
palm is the highest oil- producing crop in the tropics with potential yield
capacity of more than 10 tons of oil per hectare (ha-1). However,
current yields in the world are well below 10 tons’ ha-1 and average
about 4-6 tones ha-1 for the best managed commercial estate to 3-4
tons’ ha-1 for the managed smallholders’ farms (Murphy, 2014).
Weed
management is a major agronomic and intensive problem in the cultivation of oil
palm across West and Central Africa. Weed competition
is a serious constraint to oil palm production.
The cost, time, and frequency of weed control are contingent upon the
types of weed present. Weed species compositions across the countries in West Africa are
closely related (Akobundu et al., 2016). The high infestation and
frequent regrowth of weeds increase labour costs and inputs such as herbicides
in managing plantations for cost efficiency and profitability. Weed populations
persist in oil palm fields in spite of repeated and uniform application of weed
control practices. These persistent populations occur in spatially
characterized patterns such as patchy, aggregate and clustered (Johnson et
al., 1995). The abundance and weed species in an oil palm field changes to
the age of the plantations, cultural practices, soil type, location and season
(Sit et al., 2007).
Removal of weeds from oil palm plantations is
very slow, full of drudgery, laborious and can take up 50% of the cost of
agronomic activities (Ikuenobe and Utulu, 1999). There are also reports in
literature, which indicate that manual weeding is unsuitable where farm is size
larger than 1.5 hectares because of the difficulty in maintaining the labour
force to keep large area of crops manually weeded (NACWC, 1994). Consequently,
this method only provides short-term control of the weed and is not lasting.
Herbicide use singly or in combination with manual weeding is the preferred
choice in large scale cropping systems such as the large estate of oil palm
plantation in West Africa because they are less labour intensive (Hamel, 1986).
Chemical weed control is the most reliable and has been recognized to be an
economical practice in industrial plantations of oil palm plantation in West
Africa (Hornus, 1990) and it can reduce the reliance on the work force for hand
weeding that can delay operations in time of scarcity and increase weed
infestation in the plantation.
Therefore, chemical weeding is an ideal alternative
for weed management in oil palm production, mostly in the humid forest of Nigerian
where oil palm is mostly produced and labour for hand weeding is scarce
(Ekhator et al., 2018).
Herbicides which have been identified safe and
effective for weed control in oil palm include
Foliar (glyphosate + terbuthylazine), glyphosate, velpark4., 2,4-D, triclopyr,
triclopyr + asulam, glyphosate + metsulfuron, glyphosate + diuron, glyphosate +
indaziflam (NIFOR, 2005; Ekhator et al.,
2018). Glyphosate as isopropylamine and glyphosate trimesium have provided good
control of weeds in the oil palm (Ikuenobe and Ayeni, 1998; Ekhator et al., 2018). Glyphosate trimesium has
also been effective for some perennial weed control in the oil palm at rates of
1-3 kg a.i. ha-1 (Ikuenobe and Ayeni, 1998). The combination of two
or more herbicides could reduce application cost (Lich et al., 1997) of
herbicides applied in combination. (Diggle et al., 2003). In some
situations, mixtures or combination of herbicides provide good control at lower
dosages than dosages utilized in single applications (Ekhator et al., 2018). The high cost involved in
weed control in oil palm due to the high frequency of weeding which is usually
4-6 times annually has often caused many oil palm growers to abandon their
plantations. Weed control in oil palm involving minimal cost could be achieved
by using persistent and broad spectrum herbicides (Ekhator et al., 2018). The herbicides bipyridylium, glyphosate, urea,
sulfonylurea and alkylazine groups are the most important herbicide combinations
used for weed control in oil palm in West Africa (Ekhator et al., 2018).
The length of time some of these herbicides remain
active in the soil could be long and their after effects may prove injurious to
succeeding crops or plantings. Herbicides persistence is an important aspect to
be considered in oil palm production because in oil palm cultivation, food
crops (arable) are sometimes incorporated as intercrop and residues of applied
herbicides can potentially injure sensitive crops grown as intercrop. It is
difficult to predict the amount of herbicides in the soil and their residual
effects on arable crops grown within the palm rows at the early stage of field
planting. Herbicides residues cause great variability in plant growth and
quality and in severe cases, can result in complete crop loss and high economic
loss to oil palm growers. Bioassay
provides practical and acceptable information on the detection of low level of
herbicides in soil (Pestemer et al., 1980). The results of bioassay can be used to
guarantee non-injury to the succeeding intercrop in oil palm plantation.
Indaziflam N- [1R, 2S]–2,
3-dihyro-2, 6 – dimethyl–1 H – inden -l - yl]–6 – [ (1R)–1–fluoroethyl]-1, 3,
5, - triazine-2, 4-diamine) is a new herbicides used along with post emergence
herbicides for weed control in oil palm. It belongs to the alkylazine chemical
class, which inhibits the growth of susceptible weed seedlings through
cellulose biosynthesis inhibition (; Brosnan and Breeden, 2012). Indaziflam is
a pre-emergence herbicide for control of annual grasses and broadleaf weeds in
citrus fruit, grapes, stone fruit, pome fruit, tree nuts, olives, ornamentals,
Christmas trees, and conifers plantation. Weed seed most times come in contact
with indaziflam herbicide prior to weed emergence. For this reason, indaziflam is used along
with post emergence herbicides for weed control in oil palm because the dense
stands of living weeds at the time of weed control implementation need to be
brought down. Indaziflam has a long residual activity compared with other
pre-emergence herbicides used in weed control in oil palm. Indaziflam is a very
effective herbicide for weed control. However, due to its residual activity it
might cause injury to sensitive crops grown with the inter-rows of oil
palm. Due to the complementary nature of
oil palm with food crops at the initial stage of growth, it is essential to
evaluate the residual effect of indaziflam on some food crops grown along with
oil palm in inter-rows.
Therefore, the need for a
simple method for detecting indaziflam residues prior to intercropping
sensitive crops to assist in farming system planning and to prevent crop failures
and economic losses becomes imperative.
Bioassay using test crops in the field or in the greenhouse is
relatively easy to perform compared to more expensive and consuming chemical
assays, hence field or green house bioassays require at least two growing
seasons. A greenhouse bioassay is useful because, not only can it be used to
determine if chemical residues are present in the soil at high enough
concentration to adversely affect crop growth, but it is simple, economical and
less time consuming than any other assay.
The label on the product (indaziflam) does not include
re-cropping intervals for most arable food crops grown within the inter-rows of
palms and suggests that performing a bioassay before planting these arable
crops is pertinent in the management of both crop and weeds in oil palm
cropping systems. The essence of this research was to evaluate the relative
sensitivity of some arable crops generally grown within the inter-row of oil
palm at the initial stages of oil palm development in the field.
1.1 JUSTIFICATION OF THE STUDY
With the expansion under oil palm plantation and
increased planting in Nigeria, the volume of herbicide use in the oil palm will
continue to increase. Need for safety
issues including safety to crops, environment, non-target organisms and water
are of concern in broad herbicides use and in oil palm cultivation. In
addition, for efficient weed control, growers desire that the herbicides
provide a long duration of weed control but remain safe to applicators and
companion crops. The most herbicides used in the oil palm include Paraquat
which belongs to the class 1A or 1B herbicides (RSPO, 2008). The Principles and
Criteria of the Roundtable on Sustainable Palm Oil (RSPO, 2008) recommends that
only in exceptional circumstances would class 1A or 1B of herbicides are used
for weed control in oil palm. Consequently, suitable herbicides are now being
sought to replace these classes of herbicides.
The herbicide being evaluated for residual weed control in the oil palm is
Indaziflam (as Alion) (RSPO, 2008). In addition to the general weed control
efficiency of this herbicide, knowledge of its safety to the crop and soil
residual fate will ultimately determine the recommendation of its use in the
oil palm.
1.2 OBJECTIVES OF THIS STUDY
The specific objectives of this study were to
1. Determine
the persistence of Indaziflam in the soil at different concentrations
2. Determine
the residual effect of indaziflam herbicide on four common food inter-crops
(maize, melon, cucumber, and tomatoes) following application for weed control
in oil palm.
3. Assess
the effect of indaziflam on the weed seed bank of oil palm.
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