ABSTRACT
Investigations were conducted to study the effects of stem portions and number of stakes per stand on crop establishment, growth and yield of cassava variety NR 8082 in a tropical ultisol of southeastern Nigeria during the 2016/17 and 2017/18 cropping seasons. In each year, the experiment was laid out as a 3 x 3 factorial, arranged in randomized complete block design with 3 replications. Treatments consisted of three stem portions of different physiological ages (top, middle and basal) and three numbers of stakes per stand (1, 2 and 3). The middle and basal stem portions significantly increased percent establishment, plant height, number of nodes per plant and leaf area index at 3 MAP but had no effect on stem girth, photosynthetic efficiency and number of storage roots per plant. The best stem portion for storage root yield was, however, the top portion which produced the highest yield on average. Number of stakes per stand did not significantly affect stem girth, number of nodes per plant and leaf area index but the use of 1 stake per stand increased number of storage roots per plant, root weight and storage root yield in 2017/18 cropping season. Averaged across two seasons, number of stakes per stand did not significantly influence storage root yield. Interactions between stem portion and number of stakes per stand did not significantly affect storage root yield of NR 8082 high cyanide cassava variety in both cropping seasons.
TABLE
OF CONTENTS
Title
page i
Declaration ii
Certification
iii
Dedication
iv
Acknowledgements v
Table
of contents vi
List
of Tables viii
Abstract ix
CHAPTER 1: INTRODUCTION
Introduction 1
Objectives 4
CHAPTER 2: LITERATURE
REVIEW
2.1
Growth, development and yield of cassava 5
2.2
Effect of stakes’ size and quality on cassava 5
2.3
Effect of stem portion on cassava 7
2.4
Effect of number of stakes per stand on cassava 8
2.5
Effect of plant population on cassava 10
CHAPTER 3: MATERIALS AND
METHODS
3.1
The study site 13
3.2
Planting materials 13
3.3
Field preparation and soil sampling 15
3.4
Experimental design and treatments 15
3.5
Planting and field maintenance 16
3.6
Data collection 16
3.7
Statistical model and statistical analysis 18
CHAPTER 4: RESULTS AND
DISCUSSION
Soil
and meteorological data 20
Crop
establishment and growth 20
Photosynthetic
efficiency, yield and yield component 30
Starch
and dry matter content 36
Discussion 40
CHAPTER 5: CONCLUSION AND
RECOMMENDATIONS 43
REFERENCES 44
APPENDICES 52
LIST OF TABLES
Table 3.1 The
characteristics of cassava variety NR-8082 14
Table 4.1 The
physical and chemical properties of soil of the study site. 22
Table
4.2 Meteorological data of the
experimental site from 2016 to 2018 cropping
season. 23
Table
4.3 Effect of stem portions and
number of stakes per stand on percentage establishment. 24
Table
4.4 Effect of stem portions and
number of stakes per stand on plant height
(cm)
at different sampling dates. 25
Table
4.5 Effect of stem portions and
number of stakes per stand on stem girth at
different
sampling dates. 27
Table
4.6 Effect of stem portions and
number of stakes per stand on number of
Nodesper
plant at different sampling dates. 28
Table
4.7 Effect of stem portions and
number of stakes per stand on leaf area index
at
different sampling dates. 29
Table
4.8 Effect of stem portions and
number of stakes per stand on photosynthetic
efficiency
(Mj/m). 32
Table
4.9 Effect of stem portions and
number of stakes per stand on number of
Storage
roots per plant. 33
Table
4.10 Effect of stem portions and
number of stakes per stand on storage root
weight
(kg). 34
Table
4.11 Effect of stem portions and
number of stakes per stand on storage root
yield
(t/ha). 35
Table
4.12 Effect of stem portions and
number of stakes per stand on mean storage
root
yield. 37
Table
4.13 Effect of stem portions and
number of stakes per stand on starch content. 38
Table
4.14 Effect of stem portions and
number of stakes per stand on dry matter
content . 39
CHAPTER 1
INTRODUCTION
Cassava (Manihot
esculenta Crantz) is a perennial woody shrub native to Latin America
(Bellotti et al., 2011, El-sharkawy,
2012) and is primarily grown as an annual crop in the humid tropics. It belongs
to the family Euphorbiaceae (Alves, 2002) with about five thousand known
varieties (CIAT, 1993).It was first domesticated and grown as a food crop by
the American Indians about 4000 years ago (Renoize, 1973). Today cassava is
grown all over the tropical and subtropical zones (Latitude 300
North and South of the equator) at altitudes from sea level to 2300m; 18 to 350C
temperature range; 600mm to more than 3000mm rainfall and in rich and poor
soils of pH 4 to 9. The crop has also been found to have a very high
productivity per unit of land area and labour than most other food crops.It is
currently the world’s fourth most important staple and carbohydrate rich food
crop (El-sharkawy, 2012). Cassava provides food for more than 800million people
(FAO, 2007). It plays an important role in alleviating food problems because it
thrives and produces stable yields under conditions in which other crops fail.
It is a crop that is generally grown on marginal lands with a minimum of
agricultural inputs (Hillocks et al.,
2002). It is well known for its adaptation to poor soil conditions and responds
well to better management practices. It is also resistant to drought
(Chantaprasan and Wanapat, 2003).
In Africa, cassava is the single most important source
of dietary energy for a large proportion of the population (Cock 2011). Tufan
(2013) reiterated that no other continent depends on cassava to feed as many
people as does Africa, where 500 million people consume it daily. Cassava is
the second most important staple crop after maize, making the crop
indispensable to food security in Africa. FAOSTAT (2013) indicates that out of
a total world cassava production of 233,796,000 ton, Africa accounts for 51%
followed by Asia with a production of 35%, and the remaining production of 14%
going to the America. Though Africa’s cassava production is largely
small-scale, it accounts for more than half of the world’s cassava, or about
86million tons from over 10million hectares (Tufan, 2013).
Nigeria is the largest producer of cassava in the
world with a production figure of 52.4 million metric tons(FAO, 2008). It is a
major food crop in Nigeria and is strategically valued for its role in food
security, poverty alleviation and serves as source of raw material for agro-allied
industries with huge potential for the export market (Egesi et al., 2007, CEDP, 2005). As human
food, the cassava root is prepared in various forms such as garri, fufu,
tapioca. Besides its use as food, it is a major industrial raw material for
production of starch, alcohol, pharmaceutics, gums, confectionaries and
livestock feed (Eke-Okoro et al.,
1999). The leaves and tender shoots are important sources of vitamins, minerals
and proteins (Balagopalan 2002; Nweke et
al., 2002).
Despite the progress made in cassava research all over
the world, there has been consistent instability in the yield of cassava within
and across locations, production systems and between varieties grown under
similar fertility regime and management. According to Okeke (1994), Okereke
(1989) and FAO (1972), yield per stand can vary from 0 to over 20kg under similar
growing conditions and management. This unstable yield is a problem in cassava
growing areas and lack of precise knowledge of the contributory factors has
continued to perpetuate this problem in cassava production. Toro and Atlee
(1984) and Eke-Okoro et al., (2001),
stated that in any production system, the size and quality of the stake are of
fundamental importance for high yields. Poor quality planting material is often
associated with marginal growth and productivity of cassava (Eke-Okoro et al., 1999).
It has been affirmed that stem part from which cutting
is taken has effect on the yield of cassava (Chan et al., 1983). A mature cassava stem has three stem sections –
hardwood (Basal portion), semi-hardwood (middle portion) and shoot tip (top
portion). Shoot tips are very fragile
and have high mortality rate especially if they are subjected to moisture
stress during the first month after planting. They have high water content and
dehydrate rapidly. Cock 1985a reported that stake selection is important in
achieving high stable yield. The use of the basal part of the stem for planting
rather than the terminal has been suggested (Jennings, 1970) but the intrinsic
merit of the basal part is not obvious except that it is the oldest tissue on
the stem. Similarly, Enyi (1970) recommended the use of oldest section of the
stem for higher tuber yield. However, Leihner (1983) studied the influence of
tissue age and found that stakes from middle and lower part of the primary stem
(older stakes) sprouted much faster and were more vigorous than stakes from the
upper portion of primary stems and from secondary stems (younger stakes). CIAT
(1979) reported that in early branching varieties, younger stakes (middle and
upper portion of plant) gave greater yields.
The number of shoots per stand of cassava is likely to
influence growth, development and yield stability in cassava either by
competition between these shoots for nutrients and space or by increase in
photosynthetic surfaces arising from production of more branches or leaves by
the multiple shoots or stems Enyi (1972). These factors are likely to increase
or reduce growth rate of individual shoots. Cassava stakes when planted usually
produce many shoots which may give rise to competition for resources. The competition
may be checked by reducing the number of shoots arising at emergence. Enyi
(1972a) strongly believed that there may be reduction in the yield of
multishoot plants because of competition for assimilate, thereby, reducing the
amount of available assimilate for tuber growth. Shanmugha and Srinivasan
(1973) investigated the influence of number of shoots per plant on the growth
and yield of cassava and found that plants with two shoots out yielded the
single and multi-shoot plants, registering narrow tuber-shoot ratio. Eke-Okoro
(1997) also found that increasing shoot number from one to two improved growth,
development and yield of cassava.
In the traditional farming systems, farmers usually
plant one or more stakes per stand but the effect of such a practice on cassava
productivity may depend on such factors as cultivar, cultural practices,
quality of planting materials and location (Udealor and Asiegbu, 2005).
This study seeks to explore ways of integrating the
best stem portion and number of stakes per stand to maximize yield.
OBJECTIVES
The objectives of the present study were to assess:
1.
The contributions of stem
portions on the growth and yield of cassava variety –
NR 8082.
2.
The influence of numbers
of stakes per stand on the growth and yield of cassava variety
NR 8082.
3. The
effect of stem portion and number of stakes per stand on growth and yield of
cassava variety NR 8082.
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