Biological and Clinical Sciences Research Journal
ISSN: 2708-2261
www.bcsrj.com
DOI: https://doi.org/10.47264/bcsrj0101027
Biol. Clin. Sci. Res. J.,
Volume, 2020: e027
Original Research
EFFECTS OF HEAVY METAL TOXICITY ON MAZE SEEDLINGS
GROWTH TRAITS
SHAFIQUE F, ALI
Q*, MALIK A
Institute
of Molecular Biology and Biotechnology), University of the Lahore, Lahore,
Pakistan
Corresponding
author email: saim1692@gmail.com
Abstract
Maize is an edible cereal crop that belongs to
family Gramineae and use as an energy source for
human and animals. In our country the industrial and municipal wastewater has
been being used for irrigation purposes that contain heavy metals. These heavy
metals affect production of maize crop and soil quality. The purpose of this
study was to investigate the affect of different heavy metals on maize growth
and to asses more tolerant and more sensitive maize variety. Different
concentrations of Mn and Cr (0, 0.25Molar, 0.50Molar)
were applies in combined form and individually. Total three replicates were
carried out during research. Analysis
of variance (ANOVA), Tukey’s rang test (p ≤
0.05) were applied as statistical tool among treatment means. ANOVA indicated
the differences among five different genotypes and 9 different treatments for
all parameters were significant. Tukey’s test
indicated that higher toxic effect was shown under treatment 0.5M Mn + 0.25M Cr while less toxic effect was observed under
treatment 0.50M Mn in maize plant. The genotype 31R88
was more sensitive for metal toxicity because most of 31R88 traits were
affected under heavy metal treatments while more tolerant variety was Neelum. Hence the results of our study have suggested that
the genotype Neelum may be used for the improvement
of grain yield and productivity under heavy metal stress conditions.
Keywords: maize, heavy
metals, analysis of variance, Tukey’s rang test,
31R88, Neelum, tolerant variety
Introduction
Most of the
heavy metals are occurred in fertilizers, pesticides, municipal and compost
wastes and naturally in earth crust but when they are released in excess
concentration into the environment due to anthropogenic activities they affect plant
growth and human health (Rakesh et al., 2013).
Industrial and municipal wastewater contain less concentration of heavy metals
but long term use of these wastewaters for
irrigation purposes can affect the plant growth and restrict soil
function. Most of the plant roots help in immobilization of heavy metals but
excess concentration of heavy metals such as Cd, Cr,
Cu, Co, Ni, Zn become toxic for plant growth (Ashfaque
et al., 2016). Now a days
heavy metal accumulation is a big problem in our world. These heavy metals
accumulated into the plant bodies directly or indirectly. They inhibit the
physiological processes. High concentration of heavy metals in our atmosphere
might be resulted from agricultural activities, industrial processes, mining
activities and emission from vehicles (Salt and Rauser,
1995). Maize is considered as main food source for living organisms and main
energy source in developing countries (Chaudhary,
1983; Ali et al., 2014ab;
Ali et al., 2015; Ali et al., 2016; Ali et al., 2017; Ashraf
et al., 2020). Most of the metals are very toxic in low concentration
like As, Pb, Hg, Cd. But most of the metals are require in small
amount for plant growth,
excess concentration can
inhibit physiological processes (Raskin et al.,
1994). Essential metals like Fe, Cu, Zn,
Mg are involved in biochemical processes. Most of the
heavy metals are occurred in industrial wastewater, when they discharge into
surface water they cause serious health damages (Mohnish
and Kumar 2015; Zubair et al., 2016). In Benin city
most of the dump sites are used for agriculture purposes. Some farmers used
decomposed materials from dump sites and apply them on crops as manure which contains
heavy metals. Plants uptake these metals that are unfit for
plant growth and human consumption (Demirevska et
al., 2004). Metals like mercury,
lead, cadmium and arsenic are toxic at very low concentrations (Nkansah et al, 2010). Though most heavy metals are needed
in trace amounts by growing plants, their excess can result in plant
intoxication. The occurrence of
heavy metals in industrial
wastewater is of interest because they
are often present at
significant levels and if
discharged into surface
waters can have
severe effects on the
environment and public health. Thus the presence of concentrations
of heavy
metal in plant tissues brings
about poisoning problems in human beings and other animals feeding
on specific plant
tissues (Mazhar et al., 2020; Saif-ul-Malook et al., 2014; Tahir
et al., 2020; Zubair et al., 2016; Shan et al., 2014;
Sheng et al., 2008). These heavy metals have
the potential hazardous
effect, not only in compounds
but also on human
health. This is due to their cumulative
properties and toxicity although they are generally present in agricultural
soils at low levels. Increasing
industrialization has been
accompanied throughout the world by the
extraction and distribution
of mineral substances from their
natural deposits. However, there are large scale industries in Pakistan,
both privately and publicly owned. These include cement, pharmaceuticals,
paint, ceramics, roofing sheets, agro allied, beverages and so on. The auditing
and monitoring of metals in the environment (soil, water and foods) is fast
becoming an essential aspect of pollution studies, particularly in
industrialized area.
Material and
method
Seeds
of five different maize accessions were sown during summer season in soil
filled plastic pots. Seeds were washed with distilled water before sowing to
remove contamination. Total seven seeds were sown in each pot. Metals (Cr and Mn) were applied individually and in combined form. One set
was treated as control. Water was applied according to requirement.. Soil was turned over on regular basis. Three replicates
were carried out at a time. Plants were harvested with the interval of ten
days. Data was recorded carefully. Plant height and leaf area was measured with
the help of meter rod. Diameter of root and diameter of stem was measured with vernier caliper. Fresh weight t of root, stem, leaf was measured by using electric balance. After weighing
the fresh weight of root, stem and leaf, they were kept in oven at 40ᵒC
for 48h at biotechnology lab of The University of Lahore, Lahore. After it, dry
weight of root, stem and leaf was measured in grams by using electric balance.
Results and
discussion
It was persuaded
from results given in table 1 that there were significant difference among
maize genotypes, treatments of heavy metals and interactions between genotypes
and treatments of heavy metals. It was found that there was very low
coefficient of variation for all growth parameters indicated that there was
higher consistency for all these growth parameters. The results from table 2
indicated that there was high number of leaves per plant, leaf area, fresh stem
weight, dry leaf weight and diameter of root was found for genotype Neelum while low plant height, leaf area, dry stem weight,
dry root weight, dry leaf weight, fresh stem weight, fresh root weight, fresh
leaf weight and diameter of stem was found in genotype 31R88. The high number
of leaves per plant, leaf area, fresh stem weight, dry leaf weight and diameter
of root indicated that there were higher photosynthetic compounds in the leaves
which may be helpful for the improvement of organic compounds accumulation in
the leaves and provides resistance against various abiotic
stresses (Ali et al.,
2014ab; Ali et al., 2015; Ashraf et al., 2020; Khalil et al., 2020). The genotype Neelum may be selected as heavy metal tolerance genotypes
in maize. The treatments of heavy metals caused higher damaging effects on
genotype 31R88 (Misra and Jaiswal,
1982; Shankar et al., 2005). It has been shown from results given in
table 3 that the high plant height, fresh leaf weight, fresh root weight and
dry leaf weight was found under treatment 0.5M MnCl2 indicated that
there were very low toxic effects of this treatment. The photosynthetic rate
was not affected due to applications of this treatment as compared with the
applications of other treatments. While low plant height, dry stem weight, dry
leaf weight and diameter of root was found under treatment 0.5M MnCl2+0.25M
CrCl3 and 0.25M CrCl3 which indicated that there were
very high toxic effect of this treatment. The photosynthetic rate was affected
due to applications of this treatment as compared with the applications of
other treatments. The selection of genotypes under heavy metal treatment of 0.5M
MnCl2 may be helpful for the improvement of crop production and
productivity (Doncheva et al., 2006; Barcelo et al., 1985).
Table 1. Analysis of variance for
different growth parameters of maize seedlings under heavy metal treatments
|
Growth parameters |
Average |
Coefficient of variation |
Statistical analysis |
|
Plant
height |
8.1459+3.151 |
0.27 |
Significant |
|
L/P |
3.3674+0.0103 |
0.84 |
Sig. |
|
Leaf
are |
18.441+0.3900 |
0.79 |
Sig. |
|
Fresh
root weight |
0.2789+0.065 |
0.24 |
Sig. |
|
Fresh
stem weight |
0.4640+0.049 |
0.12 |
Sig. |
|
Fresh
leaf weight |
0.2684+0.063 |
0.11 |
Sig. |
|
Dry
root weight |
0.0252+0.005 |
1.75 |
Sig. |
|
Dry
stem weight |
0.0200+0.013 |
1.66 |
Sig. |
|
Dry
leaf weight |
0.0174+0.0013 |
2.43 |
Sig. |
|
Diameter
of root |
0.5218+0.044 |
0.55 |
Sig. |
|
Diameter
of stem |
1.3709+0.086 |
0.38 |
Sig. |
Probability level=5%
Table 2: All pairwise
comparison among different maize accessions for different growth parameters (p <
0.05)
|
Growth parameters |
Maize
accessions |
||||
|
30Y87 |
31R88 |
Neelum |
Pak afghoi |
White corn |
|
|
Plant
height |
|
- |
|
+ |
|
|
L/P |
|
|
+ |
- |
|
|
Leaf
area |
|
- |
+ |
|
|
|
Fresh
root weight |
|
- |
|
|
+ |
|
Fresh
stem weight |
|
- |
+ |
|
|
|
Fresh
leaf weight |
|
- |
|
|
+ |
|
Dry
root weight |
+ |
- |
|
|
|
|
Dry
stem weight |
+ |
- |
|
|
|
|
Dry
leaf weight |
|
- |
+ |
|
|
|
Diameter
of root |
|
|
+ |
|
- |
|
Diameter
of stem |
|
- |
|
|
+ |
Negative
sig (-)= Highly affected
Positive
sig(+)=Less affected
Table 3: All pairwise
comparison among different heavy metal treatments for different growth
parameters
|
Growth parameters |
Heavy metal
treatments |
||||
|
Control |
0.5M MnCl2 |
0.25M MnCl2 |
0.5M CrCl3 |
0.25M CrCl3 |
|
|
Plant
height |
|
+ |
|
|
|
|
L/P |
|
|
+ |
|
- |
|
Leaf
are |
|
|
+ |
- |
|
|
Fresh
root weight |
|
+ |
- |
|
|
|
Fresh
stem weight |
|
|
|
|
- |
|
Fresh
leaf weight |
|
+ |
|
- |
|
|
Dry
root weight |
|
- |
|
|
|
|
Dry
stem weight |
|
|
|
|
|
|
Dry
leaf weight |
|
+ |
|
|
|
|
Diameter
of root |
|
|
+ |
|
|
|
Diameter
of stem |
|
|
|
|
|
|
Growth parameters |
0.5M MnCl2 + 0.5M CrCl3 |
0.5M MnCl2 + 0.25M CrCl3 |
0.25M MnCl2 + 0.5M CrCl3 |
0.25M MnCl2 + 0.25M CrCl3 |
|
|
Plant
height |
|
- |
|
|
|
|
L/P |
|
|
|
|
|
|
Leaf
are |
|
|
|
|
|
|
Fresh
root weight |
|
|
|
|
|
|
Fresh
stem weight |
|
|
|
+ |
|
|
Fresh
leaf weight |
|
|
|
|
|
|
Dry
root weight |
|
|
|
+ |
|
|
Dry
stem weight |
|
- |
+ |
|
|
|
Dry
leaf weight |
|
- |
|
|
|
|
Diameter
of root |
|
- |
|
|
|
|
Diameter
of stem |
|
|
|
- |
|
Negative
sig (-) = Highly affected
Positive
sig (+) = Less affected
Conclusion
Analysis
of variance indicated the differences among five different genotypes and 9
different treatments for all parameters were significant. Tukey’s
test indicated that higher toxic effect was shown under treatment 0.5M Mn + 0.25M Cr while less toxic effect was observed under
treatment 0.50M Mn in maize plant. Variety 31R88 was
more sensitive for metal toxicity because most of the traits were affected in
31R88 under heavy metal treatments which indicates through negative sign while
more tolerant variety was Neelum which indicates
through positive significant. Positive sign indicates that plant growth was
less affected under heavy metal treatments. Plant growth and photosynthetic
rate will be high under heavy metal treatment, while negative sign indicates
that growth parameters were highly affected under heavy metal treatments. Plant
growth and photosynthetic rate will be low under heavy metal treatments.
Conflict of
interest
The
authors have declared absence of any type of conflict of interest.
References
Ashfaque,
F., Inam, A., Sahay, S. and
Iqbal, S. (2016). Influence of
heavy metal toxicity on plant growth, metabolism and its alleviation by phytoremediation-a promising technology. International
Journal of Agricultural Research Impact Factor, 6: 1-9.
Ashraf, A., Rashid, M., Ali, Q., and Malik, A. (2020).
Genetic Advances and Heritability Analysis for Seedling Growth Traits in Zea
mays under Heavy Metal Stress. Genetics
and Molecular Research 19.
Barcelo,
J., Poschenrieder, C. and Gunse,
B. (1985). Effect of chromium VI on mineral
element composition of bush beans. Journal of Plant Nutrition, 8(3): 211-217.
Chaudhary, A.R. (1983). Maize in Pakistan. Punjab Agricultural Research Coordination Board, University of
Agriculture Faisalabad.
Demirevska-Kepova,
K., Simova-Stoilova, L., Stoyanova,
Z., Hölzer, R. and Feller, U. (2004). Biochemical
changes in barley plants after excessive supply of copper and manganese. Environmental and Experimental Botany, 52: 253–266.
Doncheva,
S., Stoyanova, Z., Georgieva,
K., Nedeva, D., Dikova, R.,
Zehirov, G. and Nikolova,
A. (2006).
Exogenous succinate increases resistance of maize
plants to copper stress. Journal of plant nutrition and soil science, 169(2): 247-254.
Khalil, M., Rashid, M., Ali, Q., and Malik, A. (2020).
Genetic Evaluation for Effects of Salt and Drought Stress on Growth Traits of
Zea mays Seedlings. Genetics and
Molecular Research 19.
Mazhar, T., Ali, Q., and Malik, M. S. R. A. (2020). Effects
of salt and drought stress on growth traits of Zea mays seedlings. Life Science Journal 17.
Misra S.G., and Jaiswal,
P.C. (1982). Absorption of Fe by spinach on chromium (VI) treated
soil. Journal of Plant Nutrition, 5(4-7):755-60.
Mohnish,
P., and Kumar, N. (2015). “Effect of
Copper Mining Dust on the Soil and Vegetation in India: A Critical Review”. International
Journal of Modern Sciences and Engineering Technology (IJMSET), 2: 7376.
Nkansan, M. A., and
Amoako,
C.O. (2010). Heavy
metal content of some common spicies
available in markets in the in the
Kumasi metropolis of
Ghana. American Journal
of Scientific and Industrial Research 192:158-163.
Rakesh, S.,
and Raju, N.S. (2013). Correlation of Heavy
Metal Contamination with Soil Properties of Industrial Areas of Mysore,
Karnataka, India by Cluster Analysis. International Research Journal
of Environment Sciences, 2:
22-27.
Saif-ul-malook, M. A., Ali, Q., and Mumtaz, A. (2014).
Inheritance of yield related traits in maize (Zea mays) under normal and
drought conditions. Nat Sci 12, 36-49.
Salt,
D.E., and Rauser, W.E. (1995). Mg ATP-dependent
transport of phytochelatins across the tonoplast of oat roots. Plant Physiology, 107: 1293–1301.
Shan, C., Liu, H., Zhao, L., and Wang, X. (2014). Effects of
exogenous hydrogen sulfide on the redox states of ascorbate and glutathione in
maize leaves under salt stress. Biologia
plantarum 58, 169-173.
Shanker, A.K., Cervantes, C., Loza-Tavera, H., and Avudainayagam,
S. (2005). Chromium toxicity in plants. Environment
international, 31(5):
739-753.
Tahir, M., Rashid, M., Ali, Q., and Malik, A. (2020).
Evaluation of Genetic Variability in Wheat and Maize under Heavy Metal and
Drought Stress. Genetics and Molecular
Research 19.