Effect of Spacing and NPK Fertilizer on the Yield and Yield Components of Okra (Abelmoschus esculentus L.) in Mubi, Adamawa State, Nigeria
Field experiments were conducted at the Teaching and Research Farm of the Department of Crop Science, Adamawa State University, Mubi in 2007 and 2008 cropping seasons with the aim of assessing the effect of spacing and NPK fertilizer on the yield and yield components of okra (Abelmoschus esculentus L.). Treatments consisted of four spacing (60x30 cm, 90x30 cm, 60x60 cm and 75x45 cm) and four NPK rates (0, 100, 150 and 200 kg ha-1) in a split plot design with plant spacing allocated to main plots and fertilizer in sub plots. The treatments were replicated three times to give a total of forty eight sub plots. Parameter such as number of fruits per plant, length of fruit, fresh weight of fruits per hectare and dry weight of fruits per hectare were measured. Data collected were subjected to Analysis of Variance (ANOVA) as described by Gomez and Gomez and treatment means were separated using Duncans Multiple Range Test (DMRT). Results showed that yield and yield components such as number of fruits per plant and length of fruit were not significantly affected by spacing in 2007. However, significant difference was obtained at 52 DAS in 2008. Number of fruits per plant and length of fruits were significantly affected by fertilizer levels. In 2008, there was significant interaction in respect to fresh weight of fruits per hectare. Also, there was significant interaction between spacing and fertilizer in respect to dry weight of fruits per hectare in 2007 and 2008. The results indicated that spacing of 90x30 cm and application of 150 kg ha-1 (22.5 kgN, 22.5 kg P2O5 and 22.5 kg K2O5) of NPK gave the highest yield of okra in Mubi.
April 30, 2010; Accepted: August 20, 2010;
Published: September 28, 2010
Okra (Abelmoschus esculentus L.) is a widely cultivated vegetable crop
and can be found in almost every market all over Africa. Okra is an annual vegetable
crop, grown from seed and it is widely cultivated in the tropics for the fruits
which are used as vegetable both in the green and dried state (Kochhar,
1986). In Africa, there is great diversification of okra with the most important
production regions in Ghana, Burkina Faso and Nigeria (Raemaekers,
2001). Okra grows in all types of soils, thriving best in a moist friable
well manured soil (Kochhar, 1986). The production and economic
importance of okra as vegetable in Nigeria has rapidly increased in recent years.
The seasonal supply of this vegetable to a large extent determines how much
of it is being consumed by the majority of the people. The fresh and green tender
fruits of okra are used as vegetable; it is also sliced and dehydrated, to be
conserved for later use (Tindall, 1983). Okra is one of
the vegetable that is of great importance in improving the palatability of many
dishes in Nigeria. The young tender fruits are mucilaginous; therefore they
are often used in the tropics for soups, sauces and stews. According to Kochhar
(1986), okra is good source of vitamin A and B and also contain vitamin
C and minerals especially iodine. Overcrowding of seedlings or plants in a particular
area or spot may lead to competition among the plants for essential growth resources
like sunlight, space, water and nutrients; this may thus affect plant performance
and yield. Most soils in the tropics, especially in Mubi area are low in plant
nutrients which are necessary for plant growth and high yield. It is therefore,
necessary to supplement the amount of nutrients present in the soil to meet
crop requirement (NAERLS, 1993). If the yield of okra
is to be increased, the low fertility soils would require additional nutrients.
One of the major causes of low yield in okra in Nigeria is the inadequate information
on the application rate of inorganic fertilizer especially compound fertilizers
like NPK (Awe et al., 2006). Several experiments
on crops have generally indicated yield increase due to fertilizer application
(Cooke, 1982; Adenala, 1985; Ajari
et al., 2002). Most smallholders of okra farmers produce it at low
standard of crop husbandry and rarely care about the spacing and the application
of fertilizers to the crop, which resulted, to low yield and much labour. In
view of the uses and the economic importance and high demand of this crop, this
study was carried out to examine the effect of spacing and NPK fertilizer rates
on the yield and yield components of okra in Mubi, Adamawa State Nigeria.
MATERIALS AND METHODS
Field experiments were carried out at the Teaching and Research Farm of the
Department of Crop Science, Adamawa State University, Mubi during the 2007 and
2008 cropping seasons. The experiments were designed to study the growth and
yield of okra (Abelmoschus esculentus) as affected by plant density and
NPK fertilizer. Mubi lies within latitude 10° 08N and 10° 30N
longitude 13°N 11 E and 13°25 E in the Northern Guinea Savannah
of Nigeria (Obiefuna et al., 1997). The okra
seeds were obtained from the local farmers in Mubi. It was a local variety and
a dwarf type which grow up to a height of 70 cm and matures in 45 to 50 days.
The pods are medium long, green and five ridged, also rough and hairy.
A split plot design was used with four spacing (60x30, 90 x 30, 60 x 60 and
75 x 45 cm) as main plots and the quantity of N.P.K (15:15:15) (0, 100, 150
and 200 kg ha-1) as subplots which were replicated three times. Unit
plot size was 4 x 3 m (12 m2) with 1 and 0.5 m pathway between each
replication and the plots, respectively. The four rates of fertilizer were applied
as per treatment in two equal split doses at two and four weeks after sowing.
Weeding was done as when necessary with a simple hoe. The data collected were
number of fruits per plant, length of fruit, fresh weight of fruits and dry
weight. The data collected were subjected to Analysis of variance (ANOVA) and
means were separated using Duncans Multiple Range Test (DMRT).
RESULTS AND DISCUSSION
Effect of spacing and NPK fertilizer on number of fruits per plant is presented
in Table 1 and 2. Results on the number
of fruits per plant in 2007 were not influenced by spacing. However in 2008,
number of fruits per plant was significantly influenced by spacing treatments.
Results showed that higher fruit yield per plant was recorded in wider spacing
(75x45 cm) than closer spacing. The possible reason wider spacing produced more
healthy plants than closer spacing because of less competition for nutrients.
This result is also corroborated by Raemaekers (2001)
who reported that optimal plant density should be adjusted to the local condition
and the type of varieties to be grown. There was an increase in the number of
fruits per plant with increase in the rate of NPK fertilizer. Application of
150 kg ha-1 of NPK in both 2007 and 2008 produced the highest number
of fruits per plant of 7.7 and 7.7 cm at 52 DAS, respectively, whereas plots
that received no fertilizer produced lower number of fruits per plant of 5 and
5.4 in 2007 and 2008, respectively. For the two seasons, application of 150
kg NPK ha-1 resulted in the highest number of fruits per plant. The
cultivar appear to be more responsive to higher rate of NPK (150 kg ha-1)
as it produced significantly higher number of fruits per plant than lower rates
of NPK. This is in agreement with the findings of Smith,
Smith et al. (2001) who reported that, the use of soil amendment
(NPK) under a environment significantly influenced the growth and pod yield
|| Means of yield parameters on okra grown in 2007 cropping
season in Mubi
|DAS: Days after sowing, NS: Not significant. Means with the
same letters in the same column are not significantly different using Duncans
multiple range test
|| Means of yield parameters on okra grown in 2008 cropping
season in Mubi
|DAS: Days after sowing. NS: Not significant. Means with the
same letters in the column are not significantly different using duncans
multiple range test
Table 1 and 2 show the Effect of spacing
and NPK fertilizer on fruit length. There was no significant difference in fruit
length as a result of spacing and NPK fertilizer application in 2007. However,
significant difference was observed in fruit length at 52 DAS in 2008. Plants
spaced closely (60x30 cm) produced longest fruits of 9.1 cm. There was significant
influence in the combined analysis from the two cropping seasons results
due to spacing treatments. This was contrary to the findings of Christo
and Onuh (2005) who reported that, fruit length were found higher in plants
when grown in wider spacing than those at closer spacing. However, in agreement
with the findings of this study Gorachand and Mondal (1990)
found that spacing influences the yield of crops. There were significant influences
in the combined analysis from the two cropping seasons results (Table
3) due to spacing treatments. Spacing of 60x30 cm produced the longest fruits
at 52 DAS. The lengths of fruit were influenced by the rate of NPK fertilizer.
NPK increased the length of fruits when 200 kg NPK ha-1 was applied
giving the longest fruits at 48 DAS in both 2007 and 2008 whereas at 52 DAS,
the longest fruits were obtained from 150 kg NPK ha-1. Significant
influence of NPK was also recorded from the two years on the length of fruits.
Application of 200 kg NPK ha-1 produced the longest fruits at 52
DAS. This is accounted for by the adequacy of NPK fertilizer received.
The effect of spacing and NPK fertilizer on fresh weight of fruits is presented
in Table 1 and 2. Fresh weight of fruits
in 2007 and 2008 showed no significant difference as a result of spacing. The
component of yield in terms of fresh and dry weight of fruits were however significantly
influenced by rates of NPK fertilizer application. NPK rates increased the fresh
weight of fruits per hectare with 150 kg ha-1 giving the highest
fresh weight of 7,002 and 7,255 kg ha-1 in both 2007 and 2008 whereas
plots that received 0 kg ha-1 produced lower fresh weight of fruits
of 4469.2 and 4362.8 kg ha-1 in 2007 and 2008.
||Interaction between spacing and fertilizer on fresh weight
of Fruits kg ha-1 in 2008
|NS: Not significant, *Significant (p = 0.005)
This indicates a positive response to fertilizer as increase in yield was obtained
with the fertilizer rate up to the 150 kg ha-1 rates in both the
two years. In 2008, a significant interaction between spacing and fertilizer
in terms of fresh weight of fruits per hectare was recorded, these could have
resulted from interaction effect between spacing and fertilizer; meaning that
spacing and NPK rates combined more favorably during 2008 cropping season. The
result obtained agreed that nitrogen as well as phosphorus plays an important
role in fruit, seed and development of okra.
In this study, dry weight of fruits per hectare Table 1 and
2 was influenced by spacing. Spacing at 90 x30 cm produced
plants with greater dry weight per hectare of 828.2 kg and 800.7 kg ha-1
in 2007 and 2008, respectively. Youdeowei et al. (1999)
reported that, adequate spacing of crops is important for high yield. Application
of 150 kg NPK/ha in both 2007 and 2008 produced heavier fruits of 849.9 and
871.7 kg whereas 0 kg ha-1 produced lower dry weight of fruits ha-1
(546.2 and 539.6 kg), respectively. The means for the two cropping seasons also
differ significantly due to NPK from 0 to 150 kg ha-1 produced heavier
fruits of 860.0 kg ha-1. The results indicated that higher dosage
application of NPK up 150 kg ha-1 have potentials of increasing okra
yield. This was contrary to the findings of Obi et al.
(2005) who reported no significant increase in both fresh and dry weight
of okra plants with increasing NPK fertilizer treatment. However, in this study
okra yield and yield components were lower without the application of NPK as
results showed increase in rate of NPK increases yield of okra. Thus, agreeing
with the findings from some earlier studies in Nigeria which showed that application
of these nutrients is important for enhanced yield of okra (Adediran
and Banjoro, 2003).
The study has provided useful information on the effect of spacing and fertilizer on the growth and yield of okra at Mubi. It is very clear from the results obtained in this study that the local okra cultivar can perform well under different spacing and different levels of NPK fertilizer, but the optimum spacing of 90x30 cm with an application of 150 kg NPK ha-1 fertilizer gave the highest yield of the local okra cultivar at Mubi; as such, it is concluded that from the results obtained spacing of 90x30 cm and application of 150 kg NPK ha-1 appeared optimum for maximum growth and yield of the local okra cultivar in Mubi.
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