INTRODUCTION
Okra (Abelmoschus esculentus [L.] Moench), a member in the family of Malvaceae
is an important fruity vegetable, widely consumed and found in every market in
Nigeria (Schippers, 2000). The crop plays an
important role in human diet due to its supply of carbohydrates, proteins,
fats, minerals and vitamins (Abd Elkader et al., 2010). Its young leaves can be
used as cattle feed (Siemonsma and Kouame, 2004). The pods have been used as plasma
replacement and blood volume expander treatment (Haque
et al., 2015). Okra mucilage has been
utilized in the production of glace paper production and confectioneries (Aliyu and Ajala, 2016). Despite
the importance of okra, its productivity in Nigeria is often recorded low
yield. The low yield has been attributed mainly to poor soil fertility, use of
unimproved variety, obsolete cultural practices among other. Therefore
appropriate emphasis had to be given to higher productivity of the crop through
the selection of idea variety and nutrient supplementation to improve soil
fertility. Most farmers often depend on planting material from neighboring
farms rather than seek improved and certified seeds for their production. The
problem of low fertility can be resolved through nutrient supplementation via
organic and inorganic fertilizer application. The continuous use of inorganic
fertilizer in crop production has created declined in soil fertility, nutrient
imbalance, soil acidification, high energy cost and health hazards. Hence,
animal wastes that results in organic manure will serve as a better alternative
for high crop productivity in Nigeria. Animal manure when efficiently and
effectively used ensures sustainable crop productivity by immobilizing
nutrients that are susceptible to leaching. Nutrients contained in organic
manures are released more slowly and are stored for a longer time in the soil,
ensuring longer residual effects, improved roots development and higher crop
yields (Abou ElMagd et al., 2005). This study was
undertaken to evaluate the effect of cattle manure rates on growth and yield of
okra varieties in Wukari, Taraba
State, Nigeria.
MATERIALS AND METHODS
Study Area
This
experiment was conducted in 2020 and 2021 raining seasons at the Teaching and
Research Farm of the Faculty of Agriculture and Life Sciences, Federal
University Wukari, Taraba
State, Nigeria. Wukari (latitude 70 51´N
and 7.85 0N, and longitude 90 47´E and 9.78 0E
at elevation of 189 m above sea level.) is located within southern guinea
savanna agro-ecological zone. The area is characterized by an average annual temperature
of 28 0C and average precipitation is 1205 mm.
Experimental Design
The
study involved three okra varieties (local, Clemson and Basanti
447) and four cattle manure application rates (0, 15, 20 and 25 t ha-1)
which were laid out in 3 x 4 factorial arrangements, fitted into a randomized
complete block design (RCBD) and replicated three times. Each plot measured 2 x
2 m (4 m2) with a spacing of 0.5 m apart between plots and 1m space between
blocks. Prior to sowing, soil samples were collected from the experimental site
at a depth of 0-15 cm using auger and bulked together to form a composite
sample. The composite soil sample was air-dried and sieved through a 2 mm mesh
and analyzed for its physical and chemical properties. The soil on laboratory
analysis had pH, organic carbon, total nitrogen, exchangeable Ca, Mg, K, Na and exchangeable acidity of 7.75, 24.00 g kg-1,
1.70 g kg-1, 3.05 mg kg-1, 2.03 cmol
kg-1, 0.70 cmol kg-1, 0.24 cmol kg-1, 0.13 cmol
kg-1 and 0.05 cmol kg-1
respectively. The proximate nutrient composition of the cattle manure were pH
6.5, organic carbon 28.50 g kg−1, N 33.00 g kg−1,
P 1.31 %, 3.40 %, Ca, 0.56 %, Mg and 1.96 % K.
Cultural Practices, Data
Collection and Analysis
The
site was cleared of the existing vegetation followed by pegging and laid out
into 3 blocks and 36 plots. Eight week old cured cattle dung manure under shade
was crushed into granules and incorporated into designated plots using hoe and
spade into prepared seedbed at the rate of 0, 15, 20 and 25 t ha-1
as per treatment. Sowing of seeds was done two weeks after applying manure. The
seeds of the three varieties were soaked in water separately for 24 hours and
spread on a platform to dry few hours before sowing. The non-viable seeds were
discarded. Viable seeds were sown at a spacing of 50 x 50 cm and thinned to one
seedling per stand two weeks after sowing (WAS). Five plant were randomly
selected from each plot, tagged for data collection on growth (plant height,
number of leaves and stem girth at 8 WAS) and harvest (number of fruits, fruit
weight and yield). The obtained data were combined and subjected to analysis of
variance using GENSTAT statistical package. Differences between treatment means
were compared using least significant different at 0.05 level of probability.
RESULTS
Growth
The
effect of cattle manure application on the growth of
okra varieties are presented in Table 1. Variety and cattle application had
significant (P < 0.05) effect on the growth of okra. Increased in cattle
manure application rate brought about increased in growth and peak at 25 t ha-1.
Plants without manure application had the shortest plants. Local and Clemson
had similar heights but taller than Basanti 447
plants. The tallest plants were observed on plants treated with 25 t ha-1
of cattle manure. Clemson plants had the thickest stems while Basanti 447 had the thinnest stem but not thinner than the
stem of the local plants. Only plants supplied with 20 and 25 t ha-1
of cattle manure had thicker stems than control plants. Clemson variety
produced plants with the highest number of leaves while Basanti
447 variety had plants with the least number of leaves but similar with the
number of leaves produced by the local variety. Number of leaves produced by to
plants treated with 25 t ha-1 cattle manure had the highest number
of leaves.
Fruit Yield
Components
Fruit
yield components of okra as influenced by variety and cattle manure application
are shown in Table 2. Basanti 447 plants produced
higher number of fruits than Clemson but at par with the local variety plants.
Plants treated with 25 t ha-1 of cattle manure had the most number
of fruits but similar with the number of fruits products by plants treated with
20 t ha-1 cattle manure. Variety had no significant (P > 0.05)
effect on fruit weight per plant. All plants treated with cattle manure had
similar weights but significantly higher than control plants except plants
treated with 15 t ha-1 of cattle manure. Clemson plants produced the
highest fruit yield but comparable with the fruit yield produced by Basanti 447 plants. Plants treated with 25 t ha-1
cattle manure had the highest fruit yield but similar with fruit yields of
plants treated with 20 t ha-1 of cattle manure.
DISCUSSION
The
strategies employed to increased okra productivity in this study proved
successful as growth and fruit yield components were increased. The study
showed that the plant height, stem girth, number of leaves, number of fruits
per plant and fruit yield varied among varieties. This implied that the
productivity of each variety could be different in the same agro-ecological
zone. Similar observation has been earlier reported by Ojo
et al. (2012). Each variety exhibited differential plant
height, stem girth and number of leaves due mainly to its genetic make-up. The
Local variety exhibited higher height but thinner stem and lower number of
leaves than Clemson variety which resulted in lower fruit yield. The higher
number of fruits exhibited by Local variety than Clemson variety plant did not
result in any fruit yield advantage in favour of the
Local variety. Hence efficient utilization of photosynthetic organ (leaf) may have
been responsible for higher fruit yield in Clemson and Basanti
447. Clemson with moderate height and thick stem enhanced leaf production due
to higher assimilate accumulation (Law-Ogbomo and Osaigbovo, 2017). Leaf is an organ of photosynthesis and
higher number of leaves will enhanced photosynthetic production positively and
its translocation to the storage organ (fruit) and hence higher yield. The soil of the experimental site was of low
fertility status owing less than critical level of available phosphorus and
exchangeable calcium. Calcium plays an important role in producing plant
tissues and it enable plants to grow better. Phosphorus is important in cell
division, development of new tissue and it is also associated with complex
energy transformations in plant. Hence the deficiency of these nutrients in the
plant will hamper its growth and yield. This low fertility status of the soil
necessitated the application of cattle manure which contained high amount of
organic carbon and appreciable amount of nutrients which mineralized to release
its nutrients to supplement the soil fertility status. This trial showed the
superiority of cattle manure treated plants over control plants in terms of
higher height, thicker stems and more leaves. This is an indication that the
treated plants benefited from manure application. The higher growth exhibited
by the treated plants results in increased fruit yield. This observation is in
agreement with the findings of Ojeniyi (2000) in
which they reported that higher yield response of crops due to organic manure
application could be attributed to improved physical and biological properties
of the soil resulting in better supply of nutrients to plants. The poor
expression of vegetative characters in plants without manure treatment
(control) further confirmed the report of Akanbi and Togun (2002) who reported that nutrient availability
determine plant vegetative growth.
CONCLUSION AND
RECOMMENDATIONS
The
growth and yield characters evaluated indicated that each respond differently
in the same environment where they were grown. Clemson variety had the highest
fruit yield but similar with Basanti 447. Cattle
manure application enhanced the growth and yield of okra. Growth and yield
peaked at the highest application rate (25 t ha-1) but comparable
with 20 t ha-1. Based on these findings, Clemson variety is thereby
suggested for farmers in Wukari as against Basanti 447 and Local due to its moderate height and higher
fruit yielding as it will be resistant to lodging. The rate of cattle manure
application should be 20 t ha-1 for profit
maximization and sustainable okra production.
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