Effect of soil from different sites on growth parameters of the ornamental plants.
Abstract
A completely randomized design with three replicates was conducted at the Screen house of the Department of Crop Soil and Pest Management, Federal University of Technology Akure, Ondo State, to examine the phytoremediation potential of Codiaeum variegatum and Basella alba on contaminated soils from four locations. Soils were collected from the Mechanic workshop, Dumpsite, Forest Topsoils, and Effluent site, and filled into the buckets. Initial soil analysis was conducted on all the soils to determine heavy metal concentration (Cu, Cd, Ni, Pb, and Zn). At 12 weeks after planting, soil and plant (root and shoot) samples were analyzed to determine the heavy metals accumulated. WHO permissible limit value for heavy metal concentration in soil and plant were used as a standard to evaluate plant phytoremediation potential. Results from the study confirm the phytoremediation potential of C. variegatum and its high tolerance for the accumulation of heavy metals. B. alba plant also shows its potential in removing heavy metals from the soil, but it was not as tolerant as C. variegatum as B. alba planted in soils from mechanic workshop and effluent site had stunted growth.
Keywords
- ornamental plants
- metals
- toxics
- phytoremediation
1. Introduction
Environmental pollution has been on the rise over the past decades because of the increasing human activities on energy reservoirs, unsafe agricultural practices, and rapid industrialization. The result of these technogenic and anthropogenic activities are the major sources of heavy metals in the environment [1]. In Nigeria, soil contaminations is caused by industrial and agricultural practices such as chemical fertilizer and pesticide application, wastewater irrigation, mining activities, and metal smelting. All these human activities have contributed to problems hindering the nation’s agriculture from attaining food security.
However, agriculture in Nigeria has been facing two challenges for a long time, these challenges are; promoting environmental sustainability and enhancing food production. To ameliorate these challenges, there is a need to adopt management techniques that promote environmental sustainability. Phytoremediation has been identified as a cost-effective and easy way to sustain our environment by removing toxic elements from contaminated soils. Phytoremediation is a technique that relies on the use of plant interactions (physical, biochemical, biological, chemical, and microbiological) in polluted sites to mitigate the toxic effects of pollutants [2]. In Nigeria, heavy metals, pesticides, greenhouse gases, and hydrocarbons are pollutants that are of environmental and public health concerns.
The toxicity of heavy metals in the biota is because of their bioaccumulative nature and persistence in the environment thereby contaminating the food chains. The soil-to-plant transfer of heavy metals made it easy for metal transfer into the food chains. Metals are absorbed by plant roots and transferred to herbivorous animals along the food chain [3]. When plants like vegetables or cereals are planted in contaminated soils, the consumption of such food becomes a serious health issue to man [4].
However, because of the threat posed by the heavy metals on the growth and development of arable crops, scientists have warned against the use of crops as a phytoremediator because of their risk on human health after consumption. This is the reason for the shift to ornamental plants. The use of ornamentals continues to attract attention in recent years. In Nigeria, most ornamentals plants are not edible, therefore, the risk of contaminants entering the food chain is reduced.
The use of ornamental plants as a test plant in a phytoremediation experiment is because of their high biomass which means they can accumulate more heavy-metal concentration through their roots, into their tissues. Many studies have been conducted to evaluate the potentials of ornamental plants as in phytoremediation [5, 6, 7, 8]. However, most of the selected ornamental plants used in all the studies were not indigenous and not commonly cultivated in Nigeria. Therefore, this study aims to evaluate the phytoremediation potential of two ornamental plants in common, although not indigenous in Nigeria. In addition,
2. Objective
To examine the phytoremediation potential of
3. Materials and methods
A Completely Randomized Design with three replicates was conducted at the Screen house of the Department of Crop Soil and Pest Management, Federal University of Technology Akure, Ondo State located in the rain forest vegetation zone of Nigeria (7°16′N, 5°12′E). Soils were collected from four sites (Mechanic workshop, Dumpsite, Forest topsoil, and Effluent site) and filled into the buckets and transported to the screen house. The soils from the four locations served as the treatments. A total of 12 plastic buckets were used for each ornamental plant (4 locations replicated three times), to make it 24 plastic buckets for both ornamental plants (
Initial soil analysis was conducted on all the soils to determine heavy metal concentration. The heavy metal tested on soil and plant samples were, Cu, Cd, Ni, Pb, and Zn using Atomic Absorption Spectrometer [9]. The plant growth traits were recording, including; plant height (cm), stem girth (cm), leaf length (cm) and leaf numbers. At 12 weeks after planting (WAP), soil analysis was done to determine the remaining heavy metal concentration in the soil in order to determine the percentage of contamination reduction. In the final week of the experiment (12 weeks after planting), soil and plant (root and shoot) samples were again analyzed to determine the heavy metal concentration. WHO [10] permissible limit for heavy metal concentration in the soil and plant were used as standard and as a rating for each plant phytoremediation potential. The data were subjected to analysis of variance (ANOVA) using Statistical Package for Social Sciences (Version 17). Significant means were from each other using Tukey Test at 5% level of probability.
4. Results and discussion
4.1 Effect of heavy metal on plant growth parameters
Significant differences were recorded across the treatments (soils from different locations) for the growth parameters of
Treatments | Plant height | Number of leaves | Stem girth | Leaf length |
---|---|---|---|---|
MS | 11.88a | 10.00ab | 0.79a | 23.72c |
ES | 15.10c | 8.00a | 0.75a | 19.27a |
DS | 14.36b | 17.00c | 0.96b | 24.02d |
FS | 13.83b | 10.00ab | 0.89ab | 21.68b |
MS | 21.96a | 10.45a | 0.51a | 10.14a |
ES | 30.78b | 15.17c | 0.62a | 10.08a |
DS | 60.19c | 15.00c | 0.72a | 12.89b |
FS | 65.55d | 14.00bc | 0.66a | 11.23ab |
4.2 Initial and final metal concentrations in plant tissues and in soils
The result presented in Table 2 shows the initial concentration of heavy metals in the root and shoot of
Heavy metals | ||||
---|---|---|---|---|
Root | Shoot | Root | Shoot | |
Cu | 0.455 | 0.193 | 0.572 | 0.49 |
Cd | 0.054 | 0.01 | 0.01 | BDL |
Ni | 0.082 | 0.027 | 0.09 | 0.01 |
Pb | 0.034 | BDL | 0.032 | BDL |
Zn | 3.056 | 0.421 | 3.25 | 2.081 |
Heavy metals | Target value of soil (mg/kg) | Permissible value of Plant (mg/kg) |
---|---|---|
Cu | 36 | 10 |
Cd | 0.8 | 0.02 |
Ni | 35 | 10 |
Pb | 85 | 2 |
Zn | 50 | 0.60 |
The result presented in Table 4 and Figure 1 shows the initial and final heavy metal concentration of soils from the four sources. The results revealed that the initial and final heavy metal concentrations in all the soils were below the target value recommended by WHO for soils. However, soils from the mechanic workshop site show a considerable decrease in the heavy metal concentration present at the end of the experiment. The initial Pb concentration for the soil was 0.215 but was reduced to 0.093 in the pot where
Soil source | Initial | Final Conc. | |
---|---|---|---|
Cu | 1.567 | 0.836 | 1.484 |
Cd | 0.11 | 0.088 | 0.085 |
Ni | 0.89 | 0.26 | 0.314 |
Pb | 0.215 | 0.093 | BDL |
Zn | 37.17 | 24.9 | 31.274 |
Cu | 2.122 | 1.75 | 1.823 |
Cd | 0.153 | 0.11 | 0.142 |
Ni | 1.27 | 0.494 | 0.829 |
Pb | 0.262 | 0.21 | 0.069 |
Zn | 42.57 | 26.35 | 32.923 |
Cu | 2.014 | 0.962 | 1.216 |
Cd | 0.289 | 0.068 | 0.092 |
Ni | 1.276 | 0.398 | 0.483 |
Pb | 0.312 | BDL | 0.077 |
Zn | 32.036 | 28.719 | 30.136 |
Cu | 0.751 | 0.892 | 1.073 |
Cd | 0.072 | 0.097 | 0.047 |
Ni | 0.558 | 0.085 | 0.048 |
Pb | 0.134 | 0.145 | 0.066 |
Zn | 27.525 | 27.095 | 28.1 |
Result presented in Table 5 shows the final heavy metal concentration present in the plant parts for all the soils. For soils collected from the mechanic workshop, the Cd (0.06 for
Root | Shoot | Root | Shoot | |
---|---|---|---|---|
Cu | 0.627 | 0.038 | 0.915 | 0.085 |
Cd | 0.049 | 0.012 | 0.049 | 0.011 |
Ni | 0.078 | 0.031 | 0.079 | 0.011 |
Pb | 0.011 | BDL | BDL | BDL |
Zn | 3.038 | 0.32 | 3.063 | 0.475 |
Cu | 0.484 | 0.041 | 0.915 | 0.059 |
Cd | 0.037 | 0.01 | 0.051 | BDL |
Ni | 0.087 | 0.03 | 0.065 | 0.02 |
Pb | BDL | BDL | 0.017 | BDL |
Zn | 2.737 | 0.299 | 2.873 | 0.628 |
Cu | 1.096 | 0.12 | 0.838 | 0.514 |
Cd | 0.052 | 0.013 | 0.024 | 0.01 |
Ni | 0.07 | 0.025 | 0.085 | 0.026 |
Pb | 0.015 | 0.01 | 0.02 | 0.01 |
Zn | 3.173 | 0.125 | 2.955 | 0.315 |
Cu | 0.537 | 0.3 | 0.563 | 0.05 |
Cd | 0.057 | 0.021 | 0.023 | BDL |
Ni | 0.092 | 0.04 | 0.06 | BDL |
Pb | 0.009 | 0.003 | BDL | BDL |
Zn | 2.859 | 0.538 | 3.425 | 0.211 |
5. Conclusion
This study was conducted to determine the phytoremediation potential of two ornamental plants (
References
- 1.
Woranan N, Orapan M, Prasad M. Chapter 9: Potential of ornamental plants for phytoremediation of heavy metals and income generation. In: Prasad MNV, editor. Bioremediation and Bioeconomy. UK: Elsevier; 2016. pp. 177-217. DOI: 10.1016/B978-0-12-802830-8.00009-5 - 2.
Alaboudi K, Ahmed B, Brodie G. Phytoremediation of Pb and Cd contaminated soils by using sunflower ( Helianthus annuus ) plant. Annals of Agricultural Science. 2018;63 (1):123-127. DOI: 10.1016/j.aoas.2018.05.007. ISSN: 0570-1783 - 3.
Nica DV, Bura M, Gergen I, Harmanescu M, Bordean D-M. Bioaccumulative and conchological assessment of heavy metal transfer in a soil-plant-snail food chain. Chemistry Central Journal. 2012; 6 (1):55 - 4.
Orisakwe OE, Nduka JK, Amadi CN, Dike DO, Bede O. Heavy metals health risk assessment for population via consumption of food crops and fruits in Owerri, South Eastern, Nigeria. Chemistry Central Journal. 2012; 6 (1):77 - 5.
Liu H, Zhao H, Wu L, Liu A, Zhao F, Xu W. Heavy metal ATPase 3 (HMA3) confers cadmium hypertolerance on the cadmium/zinc hyperaccumulator Sedum plumbizincicola . The New Phytologist. 2017;215 (2):687-698 - 6.
Shuang C, Tingan Z, Shanlin Z, Ping L, Qixing Z, Qianru Z, et al. Evaluation of three ornamental plants for phytoremediation of Pb-contaminated soil. International Journal of Phytoremediation. 2013; 15 (4):299-306. DOI: 10.1080/15226514.2012.694502 - 7.
Miao Q , Yan J. Comparison of three ornamental plants for phytoextraction potential of chromium removal from tannery sludge. Journal of Material Cycles and Waste Management. 2013; 15 (1):98-105 - 8.
Wang X, Zhou Q . Ecotoxicological effects of cadmium on three ornamental plants. Chemosphere. 2005; 60 (1):16-21 - 9.
Shaltout A, Ibrahim M. Detection limit enhancement of Cd, Ni, Pb and Zn determined by flame atomic absorption spectroscopy. Canadian Journal of Analytical Sciences and Spectroscopy. 2007; 52 :5 - 10.
World Health Organization. Permissible Limits of Heavy Metals in Soil and Plants. Geneva, Switzerland: WHO; 1996 - 11.
Gadd GM. Geomycology: Biogeochemical transformations of rocks, minerals, metals and radionuclides by fungi, bioweathering and bioremediation. Mycological Research. 2007; 2007 (111):3-49 - 12.
Zhou W, Qiu B. Effects of cadmium hyperaccumulation on physiological characteristics of Sedum alfredii Hance (Crassulaceae). Plant Science. 2005;169 :737-745 - 13.
Gajewska E, Sklodowska M. Relations between tocopherol, chlorophyll and lipid peroxides contents in shots of Ni-treated wheat. Plant Physiology. 2007; 164 :364-366 - 14.
Pandey N, Pathak GC. Nickel alters antioxidative defence and water status in greengram. Indian Journal of Plant Physiology. 2006; 11 :113-118 - 15.
Ryser P, Sauder WR. Effects of heavy-metal-contaminated soil on growth, phenology and biomass turnover of Hieracium piloselloides . Environmental Pollutution. 2006;140 :52-61