ABSTRACT
Cassava nutrition and population are some of the factors that affect the yield of cassava. Some farmers prefer to plant more than one stake per stand in order to increase yield of roots without regard to the fertility status of the soils. This research was designed to determine the best source and rate of compound fertilizer (NPK) for NR 8082 variety, the optimum rates of NPK fertilizer (15:15:15) and agrolyser for NR 8082 variety and the number of stem cuttings per stand and NPK fertilizer rates for optimum stem and root production of TME 419 cassava variety in Southeastern Nigeria in 2017/2018 and 2018/2019 late cropping seasons. The experiments were factorial arrangement and fitted into a randomized complete block design (RCBD) with three replications. The first experiment involved three NPK fertilizer sources (NPK 15:15:15, NPK 20:10:10 and NPKMg 12:12:17:2) and four application rates (0, 200, 400, and 600 Kg/ha) laid out in a 3 x 4 factorial arrangement fitted into RCBD. The second experiment involved four rates of NPK 15:15:15 fertilizer (0, 200, 400 and 600 Kg/ha) and four rates of agrolyser (0, 0.8, 1.6 and 2.4 Kg/ha) in a 4 x 4 factorial arrangement laid out in RCBD. The third experiment involved four number of stem cuttings per stand (1, 2, 3 and 4) and five rates of NPK 15:15:15 fertilizer (0, 200, 400, 600 and 800 Kg/ha). The results indicated that application of NPK fertilizer (15:15:15) significantly increased dry matter content and reduced moisture content of the root tubers compared to other fertilizer sources. In 2017/2018 cropping season, application of 400 Kg/ha NPK (15:15:15) fertilizer significantly increased starch content and reduced moisture content of the storage roots. In 2018/2019 cropping season, however, NPK fertilizer application at 600 Kg/ha produced significantly higher root yield than 0 Kg/ha, although the lower rate of 200 Kg/ha gave similar results as 600 Kg/ha. Agrolyser application did not influence stem and root yields but it decreased significantly dry matter and starch contents of the tuberous roots. Increasing the number of cutting to 4 cuttings per stand significantly increased leaf area index across sampling dates in 2017/2018 and stem yields in both cropping seasons compared to 1 or 2 cuttings per stand. The use of 4 cuttings per stand in 2018/2019 also significantly increased storage root yield compared to fewer number of cuttings per stand while dry matter and starch contents of the root tubers were markedly higher at 2 or 3 cuttings than at 1 or 4 cuttings per stand in 2017/2018 cropping season. NPK fertilizer (15:15:15) application at 800 Kg/ha in 2018/2019 produced significantly higher storage root yield than the control, but not over the lower rates of 400 to 600 Kg/ha. Application of NPK fertilizer at 600 Kg/ha significantly increased dry matter content of the root relative to other fertilizer rates in 2017/2018 cropping season. Based on the findings, it is recommended that under a droughty situation in a relatively fertile soil, NPKMg 12:12:17:2 fertilizer be applied at low rate of 200 to 400 Kg/ha or fertilizer application discouraged for high dry matter and starch yields, of NR 8082 cassava variety. For TME 419 variety with little or no branching single erect stem, the use of 4 cutings per stand is recommended for high root yields and 3 and 2 number of cuttings for high dry matter and starch contents, while NPK fertilizer at 400 to 600 Kg/ha is recommended for high root yields and high dry matter and starch contents of root tubers.
TABLE OF CONTENTS
Front page i
Title
page ii
Declaration iii
Certification iv
Dedication v
Acknowledgements vi
Table
of contents vii - x
List of
Tables x - xiii
Abstract xiv
CHAPTER 1: INTRODUCTION 1 - 4
CHAPTER 2: LITERATURE
REVIEW 5
2.1 Cassava
Production and Its Role as Food Security 5 - 7
2.2 Nutritional
Value of Cassava Roots and Potential Toxicity Levels 7
- 8
2.3 Cassava Farming Methods 8 - 10
2.4 Constraints on Soil 10
2.5 Effect of NPK Fertilizer on Cassava
(Roots and Tuber) 11 - 13
2.6 Agrolyser's
Influence on Crop Production 13 – 14
2.7 Effect of Number of Cutting per
Stand on Cassava 14 - 15
2.8 Effect of Plant Population Cassava/Crop
Production 15 - 17
CHAPTER 3: MATERIALS AND METHODS 18
3.1 Study Location 18
3.2 Source
of Planting
Materials 18
3.3 Description of
Varieties 18 - 19
3.4 Soil Sampling and Analysis 19
3.5 Field Experiments 19
3.5.1 Experiment 1 19
3.5.1.1 Field preparation 19 - 20
3.5.1.2 Experimental design and treatments 20
3.5.1.3 Planting and field maintenance 20
3.5.1.4 Data collection 21 - 23
3.5.1.5 Statistical analysis 23
3.5.2 Experiment 2 24
3.5.2.1 Field preparation 24
3.5.2.2 Experimental design and treatments 24
3.5.2.3 Planting and field maintenance 24 - 25
3.5.2.4 Data collection 25
3.5.2.5 Statistical analysis 25
3.5.3 Experiment 3 25
3.5.3.1 Field Preparation 25
3.5.3.2 Experimental Design and Treatments 25 - 26
3.5.3.3 Planting and Field maintenance 26
3.5.3.4 Data Collection 26
3.5.3.5 Statistical Analysis 27
CHAPTER
4: RESULTS AND DISCUSSIONS 28
4.1 Soil
and Meterological Data 28 - 30
4.2 Experiment
1: 31
4.2.1 Growth
characteristics 31 - 33
4.2.2 Yield
and yield components 31 – 38
4.2.3 Moisture,
dry matter and starch contents of storage roots 35 - 42
4.2.4 Discussion 43 - 45
4.3 Experiment
2: 46
4.3.1 Crop
growth characteristics 46 - 48
4.3.2 Yield
and yield components 49 – 53
4.3.3 Moisture,
dry matter and starch contents of storage roots 54 - 58
4.3.4 Discussion 59 - 61
4.4 Experiment
3: 62
4.4.1 Crop
growth characteristics 62 - 64
4.4.2 Yield
and yield components 65 – 75
4.4.3 Moisture,
dry matter and starch contents of storage roots 71 - 75
4.4.4 Discussion 76 - 79
CHAPTER
5: CONCLUSIONS AND RECOMMENDATIONS 80
5.1 CONCLUSION 80 – 82
5.2 RECOMMENDATIONS 82
REFERENCES 83 – 97
APPENDICES
LIST OF TABLES
Table Page
4.1: Soil
physico-chemical properties of the experimental sites 2017/2018 and 2018/2019
cropping seasons 29
4.2: Agrometeorological
data of the experimental sites for 2017, 2018 and 2019 seasons 30
4.3: Effect
of NPK fertilizer sources and rates on Plant height (cm) of NR8082 cassava
variety at different planting dates in 2017/2018 cropping season 32
4.4: Effect
of NPK fertilizer sources and rates on Leaf area index (LAI) of NR8082 cassava
variety at different sampling dates in 2017/2018 cropping season 33
4.5: Effect
of NPK fertilizer sources and rates on stem yield (t/ha) of NR8082 cassava
variety in 2017/2018 and 2018/2019 cropping seasons 34
4.6 Effect
of NPK fertilizer Sources and rates on number of storage roots/plant of NR8082
cassava variety in 2017/2018 and 2018/2019 cropping seasons 36
4.7: Effect
of NPK fertilizer sources and rates on storage root weight (kg/plant) of NR8082
cassava variety in 2017/2018 and 2018/2019 cropping seasons 37
4.8: Effect
of NPK fertilizer Sources and rates on storage root yield (t/ha) of NR8082
cassava variety in 2017/2018 and 2018/2019 cropping seasons 38
4.9: Effect
of NPK fertilizer Sources and rates on moisture content (%) of storage roots of
NR8082 variety in 2017/2018 cropping season 39
4.10: Effect
of NPK fertilizer Sources and rates on dry matter content (%) of storage roots
of NR8082 variety in 2017/2018 cropping season 41
4.11: Effect
of NPK fertilizer Sources and rates on starch content (%) of storage roots of
NR8082 variety in 2017/2018 cropping season 42
4.12: Effect
of NPK fertilizer and Agrolyser rates on plant height (cm) of NR8082 variety in
2017/2018 cropping season 47
4.13: Effect
of NPK fertilizer and Agrolyser rates on Leaf area index (LAI) of NR8082
variety in 2017/2018 cropping season 48
4.14: Effect
of NPK fertilizer and Agrolyser rates on stem yield (t/ha) of NR8082 variety in
2017/2018 and 2018/2019 cropping seasons 49
4.15: Effect
of NPK fertilizer and Agrolyser rates on number of storage roots per plant of
NR8082 variety in 2017/2018 and 2018/2019 cropping seasons 51
4.16: Effect
of NPK fertilizer and Agrolyser rates on storage root weight (kg) per plant of
NR8082 variety in 2017/2018 and 2018/2019 cropping seasons 52
4.17: Effect
of NPK fertilizer and Agrolyser rates on storage root yield (t/ha) of NR8082
variety in 2017/2018 and 2018/2019 cropping seasons 53
4.18: Effect
of NPK fertilizer and Agrolyser rates on root moisture content (%) of NR8082
variety in 2017/2018 cropping season 55
4.19: Effect
of NPK fertilizer and Agrolyser rates on root dry matter content (%) of NR8082
variety in 2017/2018 cropping season 56
4.20: Effect
of NPK fertilizer and Agrolyser rates on starch content (%) of roots of NR8082
variety in 2017/2018 cropping season 58
4.21: Effect
of number of cuttings per stand and NPK fertilizer on plant height (cm) of
cassava variety TME 419 at different sampling dates in 2017/2018 63
4.22: Effect
of number of cuttings per stand and NPK fertilizer on Leaf area index (LAI) of
cassava variety TME 419 at different sampling dates in 2017/2018 64
4.23: Effect
of number of cuttings per stand and NPK fertilizer on stem yield (t/ha) of TME
419 variety in 2017/2018 and 2018/2019 cropping seasons 65
4.24: Effect
of number of cuttings per stand and NPK fertilizer on number of storage
roots/plant of TME 419 cassava variety in 2017/2018 and 2018/2019 cropping
seasons 67
4.25: Effect
of number of cuttings per stand and NPK fertilizer on storage root weight/plant
(kg/ha) for two cropping seasons 68
4.26: Effect
of number of cuttings per stand and NPK fertilizer on storage root yield (t/ha)
of TME 419 variety in 2017/2018 and 2018/2019 cropping seasons 70
4.27: Effect
of Number of cuttings per stand and NPK fertilizer on moisture content (%) of
TME 419 variety in 2017/2018 cropping season 72
4.28: Effect
of Number of cuttings per stand and NPK fertilizer on dry matter content (%) of
TME 419 variety in 2017/2018 cropping seasons 73
4.29: Effect
of Number of cuttings per stand and NPK fertilizer on starch content (%) of TME
419 variety in 2017/2018 cropping season 75
CHAPTER
1
INTRODUCTION
Cassava is Africa's second most important
food source in terms of calories consumed per capita (Bennett, 2015; Roothaert
and Magado, 2011). It is the main staple food in the developing world,
providing an essential nutrition for over half a billion people (Ayoola and
Makinde, 2007).
It is one of the major drought-tolerant
crops, able to grow on marginal soils and it offers flexibility to resource
poor farmers because it serves as either a subsistence or cash crop and its
wide harvesting window allows it to act as a famine reserve crop (Stone, 2002).
Cassava roots or tubers protrude from the
stem just beneath the ground's surface. The root is long and tapered, with a
firm, uniform flesh shrouded in a removable rind that is about 1 mm thick on
the outside, rough and brown (Ene, 1992). The number of tuberous roots and
their dimensions vary greatly among the different varieties. The roots may
reach a size of 30-120 cm long and 4-15 cm in diameter, and a weight of 1-8 kg
or more. A woody vascular bundle runs by the root's axis. The flesh can be
chalk-white or yellowish. Flowers that are both male and female are produced on
the same plant. The triangular-shaped fruit contains three seeds which are
viable and can be used for the propagation of the plant.
The cassava plant vary in height ranging
from 1-5 m or even more, with branching stems, green, pale or dark grey or
brown in colour (Iwuagwu, 2012). As the plant grows the major stem forks,
normally into three branches, which then divide equally. The large palmate leaves
have five to seven lobes and are carried on a long, slender petiole. They only
appear at the tips of the branches. Feeder roots that grow vertically from the
stem and from the storage roots reach a depth of 50-100 cm in the soil. This
ability of the cassava plant to obtain nutrition from below the exterior may
help to understand its growth on poor soils (Howeler, 2002). Cassava has a high
nutritional profile. It contains 60% water, 38% carbohydrates, 1% protein, and
has negligible fat of 0.3g/100g (Olumide, 2004). Cassava roots are very rich in
starch and comprise small quantities of calcium (16 mg/100g), phosphorus (27
mg/100g), and vitamin C (20.6 mg/100g) (Ravindran, 1992). However, they are
poor in protein and other nutrients. In contrast, cassava leaves are a good
source of protein (rich in lysine), but deficient in the methionine and tryptophan
(Ravindran, 1992).
In the traditional farming (bush fallow)
system, cassava is usually grown as the last crop because of its ability to
produce a reasonable yield on low fertility soils. Cassava can be planted
anytime during the growing season between March and October with equally
successful establishment (Ezedinma et al.,
1981). Higher yields of storage roots were however obtained from plantings made
between 27th August and 8th October than from early or mid-season plantings
between 23rd April and 25th June, and the lower yields from the latter was
attributed to defective bulking due to long days that prevailed at the early to
mid-season (Okigbo, 1971; Ezedinma et al.
1981). Soils of southeastern Nigeria are characterized by kaolinitic clay
mineralogy (Anikwe, et al. 2015).
They are frequently devalued, with reduced fertility and high acidity as a
result of intense continuous cropping, erosion, or leaching. Farmers have
embraced a chemical fertilizer application approach in an effort to surmount
this obstacle (Anikwe, et al. 2015). For
viable crop production, an integration of good farming techniques that do not
harm the environment and the right mix of inorganic fertilizers are suggested
(Howeler, 2002). Cassava can withstand acidic soils and, in symbiotic
relationship with soil fungi interwoven with cassava roots, the crop can absorb
nutrients, particularly phosphorus, which they use in production of photosynthates
(Howeler, 2002).
The majority of organic matter taken up by
the cassava plant is deployed to the leaves and stems, allowing the plant to
recycle nutrients within the plant-soil system. Different fertilizer rates and
types can be used such as NPK 12:12:17, NPK 20:10:10 or NPK 15:15:15 compound
fertilizers, as cassava requires a moderate supply of nitrogen and potassium to
produce high yield of tubers (Fernandes et
al. 2017). Cassava cultivation by resource-poor farmers in Nigeria has
risen significantly in recent years due to its adjustment to smaller fallow
cycles, comparative drought tolerance, capacity to flourish well in low
fertility soils, and soil storage prospects (Aduramigba and Tijani-Eniola,
2001; Olojede, 2004), but it quickly depletes the soil unless the absorbed or
lost nutrients are replaced (Ekanayake et
al. 1997; Eke-Okoro et al.,
1999). Asher et al. (1980) reported
that at a tuberous root yield of 30 t/ha the amount of major nutrients removed
from the soil at harvest were 164 kg N/ha, 31 kg P/ha and 200 kg K/ha. Low soil
fertility occurs in many cassava growing areas because the fallow periods have
become shortened as the pressure on arable land is increasing (Njoku and
Muoneke, 2008). The crop can produce a modest fresh tuber yield of 5 – 6 t/ha
on low fertility soils that would not support other crops (IITA, 1990), while
high yields can be obtained and maintained when adequate amounts of fertilizers
are applied (Howeler, 2002 and Njoku et
al., 2001). Farmers that apply fertilizers usually use only low rates
(Howeler et al., 2006), even though
the recommended fertilizer rate for cassava in Nigeria is 400 kg/ha NPK
(15:15:15) compound fertilizer (Sughai, 2010).
The response of the crop to fertilization
may however, depend on cultivar, fertilizer source, soil and seasonal
variations in rainfall pattern. Cassava population is one of the factors that
affect the yield of cassava (Udoh and Ndon, 2016). A modified trial to improve
the productivity of cassava-based systems by increasing the number of cuttings
per stand to enhance farmers' adoption was carried out by Eke-Okoro et al. (2010); who reported that
planting of more stakes of cassava in intercrop gave sustained cassava fresh
shoot size (2-5 kg) and yields(36 t/ha) in both seasons. Eke-Okoro (1997)
observed that increasing shoot number from one to two improved growth,
development and yield of cassava while Enyi (1972) strongly believed that there
may be reduction in yield of multi-shoot plants because of competition for plant
resources, thereby, reducing the amount of available assimilate for tuber
growth. Generally, farmers plant one or more stakes per stand in the
traditional farming system (Udealor and Asiegbu, 2005). The success of such
practice on cassava productivity may depend on cultivars, cultural practices,
quality of planting materials and native soil fertility (Udealor and Asiegbu,
2005). This research seeks to provide more information on the nutrition and
number of cuttings per stand of late-planted cassava for both stem and root
production in Southeastern Nigeria.
In this regard, the study has been
designed with the following objectives to:
I.
determine the best
sources and rates of compound fertilizers (NPK) for cassava stem and root production
II.
examine optimum rate of
agrolyser that can serve as supplement to NPK fertilizer for improved cassava
stem and root production
III.
evaluate the number of
stem cuttings per stand and NPK rates for optimum cassava stem and root
production.
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