ABSTRACT
Three field experiments were conducted between 2016 and 2018, in the rainforest belt of south eastern Nigeria at Umudike, to study the response of white yam (cultivar TDr 89/02475) to slip weight and NPK fertilizer, determine the effect of sett size and time of sett immersion in water on white yam (cultivar yandu) and examine effect of stake height on four aerial yam cultivars. The three experiments were all laid out as factorial in randomized complete block design (RCBD) with three replications. Results indicated that increasing white yam slip weight from 25-45g significantly increased vine length, leaf area index, shoot dry matter, number of tubers per plant and tuber yield. Application of NPK fertilizer at the highest rate of 600kg/ha increased shoot dry matter but, the optimum tuber yield was obtained from application of the moderate fertilizer rate of 400kg/ha. The 70g whole tuber of white yam increased significantly crop establishment while 60g sett weight increased shoot dry matter and tuber yield. The highest tuber yield was obtained from 60g sett, although the smaller 50g sett produced similar results. Increasing time of sett immersion in water reduced leaf area index but, increasing the time of immersion to 12 hours increased crop establishment and shoot dry matter. On the average, time of sett immersion in water did not significantly affect tuber yield. Increasing the height of stake to 1 or 2m increased significantly aerial yam vine length, number of bulbils per plant and bulbil yield in 2017 and leaf area index in 2018. The best stake height in 2017 was 2m, although, the 1m stake gave similar results. Irrespective of height of stakes, staking had no effect on yield in 2018. Cultivar Adu Ugo had significantly longer vines, greater shoot dry matter, bulbil dry matter and bulbil weight than others in 2017. Bulbil yield was significantly higher in Adu Ugo and Adu Okai than in Adu Egbe in 2017 while, no differences in yield occurred among the cultivars in 2018.
TABLE
OF CONTENTS
Title Page
Cover
page i
Declaration. ii
Certification iii
Dedication iv
Acknowledgement v
Table
of contents vi
List
of tables
viii
List of
appendices xi
Abstract xii
CHAPTER 1: INTRODUCTION
1.1 Introduction 1
1.2 Objectives 4
CHAPTER 2:
LITERATURE REVIEW
2.1 Effect
of NPK Fertilizer on Yam 5
2.2 Effect
of Slip Weight on Yam 6
2.3 Effect
of Dormancy 8
2.4 Effect of Staking 10
2.5 Effect of Variety on Yam 11
CHAPTER 3: MATERIALS AND
METHODS.
3.1 Experimental
Site 13
3.2 Planting Material 13
3.3 Experiment
1. Effect of Slip Weight and NPK Fertilizer on Growth and
Yield of White Yam Cultivar TDr
89/02475 13
3.3.1 Field
preparation and soil sampling 13
3.3.2 Experimental
design, treatments and treatments allocation 14
3.3.3 Planting and field maintenance 15
3.3.4 Records
of agronomic measurement 15
3.3.5 Statistical
model and analysis 16
3.4 Experiment 2 Effect of Sett Size and Time of Immersion in Water
on Growth and Yield of Yandu White Yam Cultivar 17
3.4.1
Field preparation and soil sampling
17
3.4.2
Experimental design, treatment and treatment allocation 18
3.4.3
Planting and field maintenance
18
3.4.4
Records of agronomic measurements 19
3.4.5
Statistical model and analysis 19
3.5
Experiment 3. Effect of Stake Height on Growth and Yield of Four
Aerial Yam Cultivars 20
3.5.1
Field preparation and soil sampling
20
3.5.2
Experimental design,treatment and treatment allocation 20
3.5.3
Planting and field maintenance
21
3.5.4
Records of agronomic measurement 21
3.5.5
Statistical model and analysis
22
CHAPTER 4: RESULTS AND
DISCUSSION
4.1
Soil and Meteorological Data 23
4.1.1
Experiment 1. Effect of slip weight and NPK fertilizer on growth 26
and yield of white yam cultivar TDR 89/02475
4.1.2
Crop growth characteristics and photosynthetic efficiency 26
4.1.3 Yield and yield components
33
4.1.4
Discussion
37
4.2
Experiment 2 Effect of Sett Size and Time of Sett Immersion in Water
on Growth and Yield of Yandu White Yam Cultivar 39
4.2.1
Results
39
4.2.2
Crop growth characteristics and photosynthetic efficiency 39
4.2.3
Yield and yield components
49
4.2.4
Discussion
55
4.3
Experiment 3 Effect of Stake Height on Growth and Yield
of
Four Aerial Yam Cultivars 57
4.3.1
Results
57
4.3.2 Crop growth characteristics
57
4.3.3
Bulbil yield and yield components 66
4.3.4 Discussion
71
CHAPTER 5: CONCLUSION AND
RECOMMENDATIONS 73
References
75
Appendices 83
LIST OF TABLES
Page
4.1 Soil physical and chemical properties
of the experimental sites in
2016/2017/2018 Cropping seasons before
ploughing . 24
4.2 Agrometeorological data of the experimental
site for 2016, 2017 and
2018-Source NRCRI, Umudike. 25
4.3 Effect
of slip weight (g) and NPK fertilizer on vine length (cm)
of
white yam cultivar TDr 89/02475 at 5MAP.
28
4.4 Effect
of slip weight (g) and NPK fertilizer on Leaf Area Index
of
white yam cultivar TDr 89/02475 at 5MAP. 29
4.5 Effect
of slip weight (g) and NPK fertilizer on Shoot Dry matter
(g/plant) of white yam cultivar TDr 89/02475
at 5MAP. 30
.
4.6 Effect of slip weight (g) and NPK
fertilizer on Photosynthetic
` Efficiency (mj/m) of white yam cultivar TDr
89/02475 at 5MAP. 32
4.7 Effect of slip weight (g) and NPK
fertilizer on number of tubers/plant
of white yam cultivar TDr
89/02475. 34
4.8 ` Effect
of slip weight (g) and NPK fertilizer on Tuber weight
(kg/plant)
of white yam cultivar TDr 89/02475.
35
4.9 Effect of slip weight (g) and NPK
fertilizer on Tuber yield
(t/ha) of white yam cultivar TDr
89/02475. 36
4.10
Effect of sett size on percent establishment of Yandu
white yam cultivar at different
sampling dates. 41
4.11
Effect of Time of sett immersion in water on Percent
establishment
of Yandu white yam cultivar at different sampling dates. 42
4.12
Effect of sett size and Time of sett immersion in water on
Vine length of Yandu white yam cultivar at 5MAP. 43
4.13 Effect
of sett size and Time of sett immersion
in water on
Leaf Area Index of Yandu white yam cultivar at
5MAP. 44
4.14 Effect
of sett size and Time of sett immersion in water on
Shoot dry matter (g/plant) of Yandu white
yam cultivar at 5MAP. 46
4.15 Effect of sett size and Time of sett
immersion in water on
Tuber dry matter (g/plant) of Yandu
white yam cultivar 5MAP. 47
4.16 Effect of sett size and Time of sett
immersion in water on
Photosynthetic Efficiency (mj/m) of Yandu
white yam cultivar
at 5MAP.
48
4.17 Effect
of sett size and Time of sett immersion in water on
Number of tubers/plant of Yandu white yam cultivar. 51
4.18 Effect
of sett size and Time of sett immersion in water on
Tuber weight (kg/plant) of Yandu white
yam cultivar 52
4.19
Effect of sett size and Time of sett
immersion in water on Tuber
Yield (t/ha) of Yandu white yam cultivar. 53
\
4.20
Effect of stake height on percent
establishment of Four Aerial Yam
Cultivars at different sampling
dates. 59
4.21
Effect of Cultivars on percent establishment on Four Aerial Yam
Cultivars at different sampling
dates. 60
4.22 Effect
of stake height on Vine Length(cm) on Four
Aerial Yam
Cultivars at 5MAP. 61
4.23 Effect
of stake height on Leaf Area Index on Four Aerial Yam
Cultivars at 5MAP. 62
4.24 Effect of stake height on Shoot dry matter
(g/plant) on four aerial yam
Cultivars at 5MAP. 64
4.25
Effect of stake height on Bulbil Dry matter
(g/plant) on Four
Aerial Yam Cultivars at 5MAP. 65
4.26 Effect
of stake height on number of bulbils/plant on Four
Aerial Yam Cultivars. 67
4.27 Effect
of stake height on Bulbil Weight(kg/plant) on Four
Aerial Yam Cultivars. 68
4.28 Effect
of stake height on Bulbil Yield (kg/ha) on Four
Aerial Yam Cultivars. 70
LIST
OF APPENDICES
Page
1. Analysis
of variance table on effect of slip weight (g) and NPK fertilizer on
tuber
yield (t/ha) of white yam cultivar
TDR 89/02475 in 2016. 83
2. Analysis
of variance table on effect of slip weight (g)
and NPK fertilizer on tuber
yield (t/ha) of white yam cultivar
TDr 89/02475 in 2017. 84
3. Analysis
of variance table on effect of sett size and time of sett immersion in water
on
tuber yield (t/ha) of yandu white yam cultivar in 2016. 85
4. Analysis
of variance table on effect of sett size and time of sett immersion in water
on tuber yield (t/ha) of yandu
white yam cultivar in 2017. 86
5. Analysis of variance table on effect of stake
height on growth and yield Of four
aerial
yam (Dioscorea
bulbifera) cultivars on tuber yield (t/ha) in 2017.
87
6. Analysis
of variance table on effect of stake height on growth and yield of four aerial
yam (Dioscorea bulbifera)
cultivars on tuber yield (t/ha) in 2018. 88
CHAPTER
1.
INTRODUCTION
Yams
(Dioscorea spp) are important food
crops which originated in the tropical areas of Africa, South-east Asia, and
South America (Burkill, 1960). The six most economically important species
grown as staple foods in Africa are: D.
rotundata (white yam), D. cayenensis
(yellow yam), D.alata (water yam), D.esculenta (Chinese yam), D. dumentorum (three-leaved yam), and D. bulbifera (aerial yam)(Onwueme,
1978). The yam tuber is a good source of energy mainly from the carbohydrate
content since, it is low in fat and protein. The tuber also contains
pharmacologically active substances such as dioscorine, saponin, and sapogenin.
Dioscorine, which is the major alkaloid in yam, is medicinally, a heart
stimulant (Eka, 1985). Yam is a good source of industrial starch whose quality
varies with species. Apart from being an important staple food, it is
considered a man’s crop in Nigeria and has ritual and socio-cultural
significance; yam is the food of choice at many ceremonies and festivals, and
an indispensable part of bride price (Hahn et
al., 1987). Yams are eaten in boiled or roasted forms. It can be processed
into various food forms in Nigeria and the forms include- pounded yams, boiled
yams, roasted or grilled, fried yam slices, and yam balls, marshed yam, yam
chips and flakes. Fresh tubers are also peeled, chipped, dried and milled into
flour. Decaying tubers also serve the same purpose in some parts of Nigeria
especially in the Western part where it
is used in preparing a special delicacy called “amala”
Many
technologies have been developed in yam aimed at increasing its production more
especially, in generating planting materials, which is the major bane in yam
production and which accounts for over 40% of total cost of its production (Ezeh,
1991). Some of these technologies include- the traditional method (Nweke et al., 1991; Aighewi, 1998) with
multiplication ratio of 1:4-1:8., partial sectioning technique (Nwosu, 1975)
with multiplication ratio of 1:10, minisett technique (Okoli et aI.1982) with multiplication ratio of
1:30, micro sett technique (Ikeorgu and
Nwokocha.,2001) with multiplication ratio of 1:90, tissue and organ culture
(Tissue culture) technique (Yam and Arditt, 2009) with multiplication ratio of
1:1,800, vine cutting technique (Acha et
al., 2004; Kikuno et al., 2007;
Agele et al., 2010) with
multiplication ratio of 1:900, use of aeroponics system (Maroya et al., 2014) with multiplication ratio
of 1:540, temporary Immersion Bioreactor systems (Balogun et al., 2014) with multiplication ratio of 1:1,800, and use of
botanical seeds (Alvarez and Hahn 1984).
While,
the traditional method involves milking, (the Anambra system), and cut setts,
tissue culture technique encourages exchange of disease free planting material.
Aside from the above techniques, the yam slip method is another technique that
could be used in yam propagation.
The
slip is that portion of a sprouted yam tuber with a small flesh that is usually
discarded when a tuber is peeled for cooking or cut into mini sett or micro
setts for planting (IITA, 2009).
The slip method of yam propagation
technique entails the use of the cormous structure at the head of the tuber and
the associated shoot that arises from it after natural tuber dormancy release.
The non green, achlorophyllised slips derived from tubers of white yam show
high morphorgenetic ability which is attributed to probably
phytochrome-mediated responses. The direct field planting of freshly plucked non green
slips is agronomically ideal. The use of yam slip in propagation guarantees a
higher multiplication ratio that is about 20-50 times more than the
conventional method used (Dalong et al., 1990). It also reduces production cost to
about 50%, provides practicable, clean, and healthy planting materials as well
as ensures the production of more planting materials at the shortest possible
time and, at a cheaper cost (Dalong et
al., 1990; IITA, 2009). Little attention has been given to yam propagation
through the use of slip and as a consequence, information on the use of this
technique is scanty.
Growth,
development and final yield of a crop depend on nutrient availability in the
growing environment of the crop aside from climatic and management factors (Baiyeri et al., 2013). As a tuber crop producing a large amount of starch,
yams require high amounts of nutrients especially nitrogen and potassium
(Okpara et al., 2014). There is however, limited research information on the responses of the various
techniques used in generating planting materials in yam production to agronomic
management involving fertilizer needs. Continued land degradation, rapid
population growth (FAO, 1981), continuous cropping and leaching have drastically
reduced the fertility status of most farmlands in the humid tropics, thereby
posing a problem to sustainable crop production especially for crops such as
yams, which make high demands on nutrients. Although, fertilizer application
for yam has mainly been based on the application of NPK fertilizer at 400kg/ha
(Eke-Okoro, 2006), regardless of planting material (Ikeorgu, 2003; Ikeorgu and
Igbokwe, 2002), a higher rate of 600kg/ha has been recommended by Okpara et al (2014)
for white yam micro sett especially at high population densities of 60,000
plants/ha and beyond. Fertilizer best management practices require the
application of the correct fertilizer at an appropriate rate, time, and
place to obtain best yields.
Staking and
dormancy also pose a challenge to yam production. For climbing plants like
yams, staking or provision of support is necessary to help the twining yam
stems display their leaves to attract adequate solar energy for efficient
photosynthesis (Aighewi et al., 2014). If yams are not staked, they will be
devastated by such disease as anthracnose (Colletotrichum
gloeosporioides.Penz) (Chadha, 2002).
Priming prior to
planting is a process of hydrating or dehydrating seeds or planting materials
following various protocols which result in improvement in vigour, increased
germination or sprouting rate and more uniformed emergence under a wide range
of field environments (Modi, 2005). Hydro priming (hydration of seed with water
only) is the simplest approach to increase the percent and rate of germination
or sprouting and increase the uniformity of
stand establishment under stress conditions especially in dry areas
(Clark et al., 2001; Mavi et al., 2006; Berchie et al., 2010). The water imbibed by the
planting material activates enzymes and facilitates metabolism of stored starch
and protein (Kikuchi et al., 2006)
and thus, water absorption is the most important event for ensuring nutrient
supply to the embryo and to generate energy for the commencement of seedling growth (Abebe and Modi,
2009). However, the amount of water imbibed for active seedling growth and
yield may depend on species or variety and on the duration of sett immersion in
water.
1.2
Objectives.
The objectives of
the present study were to :
i.
evaluate the effect of slip weight and NPK
fertilizer on growth and yield of white yam (D. rotundata) cultivar TDr 89/02475.
ii.
determine effect of sett size and time of
immersion in water on growth and yield of white yam cultivar, Yandu.
iii.
examine effect of stake height on growth and
yield of four aerial yam (D. bulbifera) cultivars.
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