Growth of Calopogonium mucunoides Desv. in Crude Oil Contaminated
Soil: A Possible Phytoremediating Agent
Calopogonium mucunoides Desv. was subjected to varying concentrations
of crude oil equilibrated with water. Five treatments viz 0, 5, 10, 20 and 30%
were used in a Randomized Complete Block Design (RCBD) with three replicates.
These treatments were applied once to two weeks old seedlings of C. mucunoides
using ring method and the plants were allowed to stand for eight weeks. The
effects of these treatments on plant height, leaf area and biomass of C.
mucunoides were studied. The total chlorophyll contents were also studied.
The study showed that 5% treatment gave the highest value for plant height and
biomass content while 10% treatment gave the highest value for leaf area and
chlorophyll content when compared to control (0%) respectively. It was observed
that as the concentration of the crude oil increases, there were corresponding
reduction in the plant height, leaf area, biomass and chlorophyll content. These
results implied that C. mucunoides can tolerate to some degree of crude
oil contamination and thus can be used for phytoremediation in crude oil contaminated
Received: March 25, 2013;
Accepted: January 17, 2014;
Published: March 06, 2014
Calopogonium mucunoides Desv. is a vigorous, creeping and twining hairy
herbaceous perennial plant, forming tangled foliage of about 30-40 m deep in
height. In recent years, C. mucunoides has been used as cover plant for
soil palm and rubber plantations. It is a shade tolerant plant and can quickly
establish a dense cover and secrets chemical substances which inhibit the growth
of other weeds.
Adriano et al. (1998) considered the soil as
an integral part of the natural ecosystem and suggest that environmental sustainability
depends largely on it. Introduction of contaminants into the natural environment
can cause adverse environmental change. Adedokun and Ataga
(2007) reported that crude oil contamination alters soil microbial community
and affect the growth of cowpea. Studies have shown that symptoms of oil pollution
in soil were typical of extreme nutrient deficiency in plants (Agbogidi
and Eshegbeyi, 2006) while nutrient deficiency symptoms could be directly
proportional to water uptake (McKee, 1995). According
to Onuoha et al. (2003), the hydrophobic characteristics
of oil prevent normal oxygen exchange between soil and the atmosphere. For example
Ogbohodo et al. (2001) reported that maize exposed
to high pollution level inhibited its growth performance. Asuquo
et al. (2001) also reported that increased crude oil concentration
resulted in reduced seedling growth of Abelmoschus and Telfairia.
Onuh et al. (2008) earlier reported that the
adverse effect of crude oil pollution is a function of dosage and concentration
of pollutant. Okonwu and Amakiri (2009) reported that
crude oil equilibrate with water causes an increase in the lag phase preceding
germination and also a decrease in germination percentage of IT84S-2246 variety
of cowpea, V. unguiculata. Okonwu et al.
(2010) also reported that the foliage of maize treated with crude oil caused
reduction in the chlorophyll content leading to defoliation of leaves which
amounted to retardation in growth. According to Okolo et
al. (2005), oil pollution increases soil organic carbon but reduces
its nitrate and phosphorus contents. White et al.
(2000) reported that the process of remediating crude oil contaminated soils
either by ex situ or in situ techniques can be costly. This study
therefore, was conducted to examine growth of C. mucunoides in crude
oil contaminated soil and possibly establish it as a phytoremediating agent.
MATERIALS AND METHODS
Seeds of C. mucunoides were collected from matured plants growing in
the Biodiversity Conservation Area, University of Port Harcourt. These seeds
were removed from the fruits, air dried and stored at room temperature. Crude
oil was collected from Shell Petroleum Development Company of Nigeria Limited
(SPDC) Oyigbo flow station. Soil samples were obtained from the upper soil surface
layer (0-15 cm) and the field experiment was laid out in a Randomized Complete
Block Design at the University of Port Harcourt Botanical Garden. In preparing
the different concentrations of crude oil equilibrated with water, a known volume
of distilled water was added to a known volume of crude oil. This was carried
out with the aid of a measuring cylinder calibrated in milliliters. It was mixed
thoroughly with the help of the shaker. Various mixtures, that is, 0, 5, 10,
20 and 30% concentrations were obtained. These treatments were applied to two
weeks old seedlings of C. mucunoides using ring method and the plants
were allowed to stand for eight weeks. The growth parameters assessed were plant
height, leaf area and biomass of C. mucunoides in soil containing varying
concentrations of crude oil equilibrated with water. Total chlorophyll of C.
mucunoides was determined using the method of Stewart
et al. (1984).
Statistical analysis: The data obtained from study were subjected to
statistical analysis by Analysis of Variance (ANOVA) using 5% level of significance.
The result of the effect of varying crude oil application on plant height,
leaf area and biomass of C. mucunoides are shown in Table
1. The plant height and leaf area obtained from the treatments are as follows:
0% (45 cm, 3.1 cm2), 5% (76 cm, 3.0 cm2), 10% (72 cm,
3.5 cm2), 20% (53 cm, 2.1 cm2), 30% (27 cm, 3.0 cm2),
respectively. The results indicated an appreciable increase in plant height
from 0-5% treatment and then gradually decrease from 10-30% treatment. The plant
height for 5% treatment was significantly different (p<0.05) when compared
with other treatments except 10% treatment. Among the treatments, the leaf area
did not show any trend. This result shows that C. mucunoides has some
level of tolerance to crude oil applications. However, 10% treatment gave the
highest value for leaf area. The resultant plant biomass showed that 5% treatment
gave the highest value which was significantly different among treatments at
p = 0.05. The highest value for total chlorophyll content of C. mucunoides
was obtained at 10% concentration of crude oil equilibrated with water as
shown in Fig. 1. The trend of data showed that as the volume
of crude oil increases, the biomass content of C. mucunoides decreases.
|| Effect of varying concentration of crude oil equilibrated
with water on the plant height, leaf area and biomass of C. mucunoides
|SE: Standard error, SD: Standard deviation
|| Effect of varying crude oil concentration on the chlorophyll
The results indicated an enhancement of plant height, leaf area, biomass and
total chlorophyll content with the concentrations of 5-20% crude oil application
when compared with the control (0%) treatment. However, further increase in
the crude oil concentration to 30% decreased plant height, leaf area, biomass
and total chlorophyll content. This result implied that C. mucunoides could
tolerate crude oil levels within 5-20% concentrations, thus C. mucunoides
has potential for phytoremediation of crude oil contaminated soils. Agbogidi
et al. (2005) reported that differential changes in the rate of leaf
growth may be associated with anatomical and morphological change caused by
the oil treatment. Okonwu and Amakiri (2009) also reported
that crude oil application increased the chlorophyll and lipid contents of V.
unguiculata. The mechanism for thriving or growing in crude oil polluted
soil may be attributed to its nitrogen fixing ability. It could also be that
the development of extensive fibrous and deeper root system by C. mucunoides
plant aids in its tolerance and survival strategies to cope with water stress
imposed by the crude oil treatment. White et al. (2000)
reported that microbial analysis of vegetated sites revealed a significantly
higher population of total hydrocarbon, alkane and polynuclear aromatic hydrocarbon
degraders to be present in soils vegetated with legumes.
The study has shown that C. mucunoides could be used to phytoremediate
crude oil polluted site due its potential to tolerate some levels of crude oil.
The increased in leaf area obtained showed a corresponding increase in the total
chlorophyll of C. mucunoides.
1: Adedokun, O.M. and A.E. Ataga, 2007. Effects of amendments and bioaugumentation of soil polluted with crude oil, automotive gasoline oil and spent engine oil on the growth of cowpea (Vigna unguiculata L. Walp). Sci. Res. Essay, 2: 147-149.
2: Adriano, D.C., A. Chlopecka and K.I. Kaplan, 1998. Role of soil chemistry in soil remediation and ecosystem conservation. Soil. Sci. Soc. Am. Special Publ., 52: 361-386.
3: Agbogidi, O.M., B.C. Okonta and D.E. Dolor, 2005. Socio-economic and environmental impact of crude oil exploration and production on agricultural production: A case study of Edjeba and Kokori communities in Delta State of Nigeria. Global J. Environ. Sci., 4: 171-176.
CrossRef | Direct Link |
4: Agbogidi, O.M. and O.F. Eshegbeyi, 2006. Performance of Dacryodes edulis (Don. G. Lam H.J.) seeds and seedlings in a crude oil contaminated soil. J. Sustainable For., 22: 1-13.
CrossRef | Direct Link |
5: Asuquo, F.E., I.J. Ibanga and N. Hungafa, 2001. Effects of Qua Iboe crude oil contamination on germination and growth of Okra (Abeloschus esculintus L.) and fluted pumpkin (Telflaria occidentalis L.). Proceedings of the 27th Annual Conference of the Soil Science Society of Nigeria, November 5-9, 2001, University of Calabar, Nigeria -
6: McKee, K.L., 1995. Interspecific variation in growth, biomass partitioning and defensive characteristics of neotropical mangrove seedlings: Response to light and nutrient availability. Am. J. Bot., 82: 299-307.
Direct Link |
7: Ogbohodo, I.A., E.K. Iruafa, I.O. Osenwota and J.U. Chokor, 2001. An assessment of the effect of crude oil pollution on soil properties, germination and growth of maize. Proceedings of the 27th Annual Conference of the Soil Science Society of Nigeria, November 5-9, 2001, University of Calabar Nigeria -
8: Okolo, J.C., E.N. Amadi and C.T.I. Odu, 2005. Effects of soil treatments containing poultry manure on crude oil degradation in a sandy loam soil. Applied Ecol. Environ. Res., 3: 47-53.
Direct Link |
9: Okonwu, K. and J.O. Amakiri, 2009. Effects of crude oil pollution on the germination, growth development of IT84S-2246 variety of cowpea, V. unguiculata (L.) Walp. Nig. J. Plant Prot., 26: 112-121.
10: Okonwu, K., J.O. Amakiri, M.M. Etukudo, S.E. Osim and A.A.J. Mofunanya, 2010. Growth and evelopment response of Maize (Zea mays) in crude oil pollution treatment. Global J. Environ. Sci., 9: 1-5.
11: Onuh, M.O., D.K. Madukwe and G.U. Ohia, 2008. Effects of poultry manure and cow dung on the physical and chemical properties of crude oil polluted soil. Sci. World J., 3: 45-50.
Direct Link |
12: Onuoha, C.I., A.E. Arinze and A.E. Ataga, 2003. Evaluation of growth of some fungi in crude oil polluted environment. Global J. Agric. Sci., 2: 80-81.
Direct Link |
13: Stewart, E.A., H. Grimshaw, J. Max and Q. Christopher, 1984. Chemical Analysis of Ecological Materials. Black Well Scientific Publications, USA., pp: 293-294
14: White, P.M., W.D. Kirkpatrick, D.C. Wolf and G.J. Thoma, 2000. Phytoremediation of Crude Oil Contaminated Soil. University of Arkansas, Fayetteville