ABSTRACT
Two field experiments were conducted in 2008 and 2009 cropping seasons at the linkage
farm of the University of Nigeria, Nsukka to evaluate growth and yield response of (Taro)
Colocasia esculenta to plant spacing and NPK fertilizer on the plains of Nsukka with the
objectives of identifying best performing cultivar, optimum plant spacing and NPK fertilizer
rate. Experiment one was laid out in a 3×5 factorial in Randomized Complete Block Design
(RCBD) in which Factor A is plant spacing comprising 0.3m x 1.0m, 0.4m x 1.0m and 0.5m x
1.0m levels while Factor B is taro cultivars consisting of Nkpong, Odogolo, Nworoko, ugwuta
and Nachi. Experiment two was laid out in a 5×6 factorial in RCBD in which Factor A is taro
cultivars as mentioned above and Factor B NPK fertilizer with 6 levels among which are :
Okg/ha, 100kg/ha, 150kg/ha, 200kg/ha, 250kg/ha, and 300kg/ha with three replications in
each of the two experiments. F-LSD was applied to detect significant differences at 5%
probability level. The result showed that the mean rainfall for 2009 planting season was
higher than that of 2008. The soil was texturally clayey and moderately acidic with a PH of
5.0 .Cultivar diferences in cormel and corm yield were not significant, however Nworoko
produced the highest yield of 11.0 t/ha among the cultivars. Plant spacing produced
significant effect (P=0.05) in the tuber yield in both 2008 and 2009. Planting at 0.3m x 1.0m
significantly gave the highest tuber yield/ha among the three plant spacing. NPK fertilizer
showed significant effect (P=0.05) on the measured traits with 200kg/ha and 150kg/ha
producing the highest yield of 43.0 t/ha and 3.0 t/ha respectively, in both 2008 and 2009.
TABLE OF CONTENTS
Title page……………………………………………………… …………………………………………………….……… i
Certification page………………………………………………… ………………………………………………… .ii
Dedication……………………………………………………… ……………………………………………………. .iii
Abstract………………………………………………………….. …………………………………………………… iv
Acknowledgement………………………………………………. ……………………………………………….. .v
List of tables……………………………………………………… …………………………………………………. viii
Cocoyam photographs………………………………………………… .xvii
Introduction…………………………………………………… ……………………………………………………. 1
Literature review………………………………………………… ……………………………………………….. 5
Materials and methods…………………………………………. ……………………………………………… 15
Location of experiments……………………………………… ……………………………………………….. 15
Experimental layout …………………………………………… ……………………………………………….. 16
Records and agronomic measurements ………………… …………………………………………….. 17
Soil analysis ……………………………………………………………………………………………………… 21
Meteorological data …………………….. ……………………………………………………………………. 21
Statistical analysis ……………………………………… ……………………………………………………….. 21
Result…………………………………………………………… ……………………………………………………… 22
Experiment one 2008………………………………………… …………………………………………………. 25
Experiment two 2008………………………………………… …………………………………………………. 38
Experiment one 2009………………………………………… …………………………………………………. 51
Experiment two 2009………………………………………… …………………………………………………. 62
Combined analysis for 2008 and 2009 on plant spacing experiment ………………………. …..76
Combined analysis for 2008 and 2009 on fertilizer experiment ……………………………..……..146
Discussion………………………………………………………………….……………………….………………………..221
Conclusion ………………………………………………………….…………………….………………………………….224
References…………………………………………………………………………………………….……………………..
CHAPTER ONE
Cocoyam is a monocotyledonous crop that has (the character of being) an
underground stem. It differs from yam as it is not a tuber but a corm. Eatable
cocoyam belongs to the family of plants called Araceae or Aroids with two generataro
(Colocasia) and Tania (Xanthosoma) (Uguru, 1996).
Colocasia esculenta is believed to have originated in South-East Asia while
Xanthosoma sagittifolium is indigenous to tropical America and the West Indies
(Uguru, 1996). The mode of attachment of the long petiole to the large lamina forms
the main difference between these two species of cocoyam. The petiole in Colocasia
esculenta attaches the lamina at some point about the middle of the lamina whereas
in Xanthosoma, the petiole is attached to the edge of the lamina at a deep
indentation that tends to partition the base of the lamina into two lobes (Okpul et al.,
2002).
Cocoyam is one of the four most important staple foods in Nigeria, ranking
third after yam and cassava, the fourth being sweet potato (Knipscheer and Wilson,
1980). Normally, cocoyam is grown for the corms and cormels, although the leaves,
petioles and flowers are also eaten as vegetables in soup during the vegetable-lean
periods. Alternatively the leaves can be fed to cattle and pigs as browse or used for
wrapping processed food like “akpu” and sliced cooked oil bean seed (Ezedinma,
1987); paste called “foo-foo” or “akpu. Cocoyam leaves are equally used for wrapping
and preserving of colanuts, bitter cola, etc. Cocoyams are of great importance as
they are subsistence staple food for the aged (Okwuowulu, 2000). Plucknett (1970)
also stated that cocoyam is food for the children with allergy and for persons with
intestinal disorder. It has high content of pentosans and digestible crude proteins
when compared with other root crops (Oyenuga, 1968) and is a source of
pharmaceutical and industrial alcohols (Villanueva, 1986). Parkinson (1981) stated
that cocoyams contain significant quantities of amino acids. Ohiri et al (1996) stated
that only 24% of the croppable land for cocoyams in Nigeria is under cultivation. Taro
(colocasia esculenta) is the fourteenth most consumed vegetable worldwide and
comprises the diet of 300 million people (Brown, 1998). About a million metric tonnes
of taro is produced globally from an estimated area of 2 million ha. (FAO, 2006).
Taro is a staple food for many people in developing countries in Africa, Asia
and the Pacific (Agueguia et al., 1992). It is produced mainly in Africa (especially in
Nigeria) and Asia (mainly China), but it is most important per capita in oceanic
(Howeler et al., 1993; Onwueme, 1999). The cultivated species of taro may be
distinguished into two main groups; the “eddoes” and the “dasheen” types (Kizerbo,
1990; Onwueme, 1994; Valerior, 1988; IPGRI, 1999). The eddoes types have
cormels that may be 5-20 in number and become as big as the mother corm. The
cormels are usually absent in the dasheen types and it is the mother corm which is
the main storage organ (IPGRI, 1999). The corm and cormel which are the major
economic part have a nutritional value comparable to potato (Wang, 1983), while the
young leaves and petioles which are occasionally used for food contain about 23%
protein on a dry weight basis. It is also rich source of calcium, phosphorus, iron,
vitamin C, thiamine, riboflavin and niacin, which are important constituents of human
diet (Onwueme, 1999; Ndon et al., 2003). Where grown in Uganda, Taro corms have
a high economic value in urban markets. Its production provides employment to
many people and the crop maintains ground cover in the fields (Talwana et al., 2009)
In spite of the advances made in cocoyam research, several factors remain as
challenges to sustained cocoyam production in Nigeria. The ignorance of the nutritive
value and diversities of food forms from cocoyam by a large percentage of the
populace is a major limiting factor to general acceptability and extensive production
of the crop. The notion that cocoyam is a poor man’s crop is still prevalent and needs
to be dispelled through the extension of proper information about the crop.
Colocasia esculenta (L.) Schott has not been researched upon in respect to
plant spacing and NPK fertilizer rates in the ecological zone of Nsukka. In view of the
above reason, this study was undertaken with the following objectives:
i To identify best performing cultivar of Colocasia esculenta
ii To determine optimum plant spacing
iii To determine optimum NPK fertilizer rate
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