Document 2446101

Advances in Environmental Biology, 8(4) March 2014, Pages: 980-984
AENSI Journals
Advances in Environmental Biology
ISSN-1995-0756
EISSN-1998-1066
Journal home page: http://www.aensiweb.com/aeb.html
Influence of the Electromagnetic Fields on Some Biological Characteristics of
Lepidium sativum L.
Elham Bagheri Abyaneh, Ahmad Majd, Sayeh Jafari, Golnaz Tajaddod, Fahimeh Salimpour
Department of Biology, Faculty of Biological Sciences, North-Tehran Branch, Islamic Azad University, Tehran, Iran.
ARTICLE INFO
Article history:
Received 14 Feb 2014
Received in revised form 24
February 2014
Accepted 29 March 2014
Available online 14 April 2014
Key words:
electromagnetic fields, germination,
development, mitotic index,
chlorophyll, carotenoid, protein
content, leaf peroxidase.
ABSTRACT
Extremely low frequency (ELF) magnetic field can initiate a number of biochemical
and physiological alterations in biological systems of different species. Our
investigation focused on plants grown from wet and dry seeds pretreated with 3.8 mT
electromagnetic fields (EMFs) for 30 and 60 minutes. Petri dishes containing moist
seeds (seeds soaked in water for 7and 14 h) and dry seeds were placed between the coil
of electromagnetic field generator. Results showed that electromagnetic fields
treatments increased the speed and percentage of seeds germination, seedlings growth
and also increased fresh and dry weight compare to control for most treatment groups.
The electromagnetic fields also enhanced carotenoid, protein contents and peroxidase
activity, but electromagnetic fields did not affect chlorophyll a and b.
© 2014 AENSI Publisher All rights reserved.
To Cite This Article: Elham Bagheri Abyaneh, Ahmad Majd, Sayeh Jafari, Golnaz Tajaddod, Fahimeh Salimpour., Influence of the
Electromagnetic Fields on Some Biological Characteristics of Lepidium sativum L. Adv. Environ. Biol., 8(4), 980-984, 2014
INTRODUCTION
Life on earth has evolved in a sea of natural electromagnetic fields. Over the past century, this natural
environment has sharply changed with introduction of a vast and growing spectrum of man-made
electromagnetic fields [1].
Magnetic field can affect chemical bonds between adjacent atoms with consequent production of free
radicals [17]. Recent findings suggest that ELF-magnetic field can increase free radical life-span of cell [13,28].
A potential link between EMFs and its effects on living organisms is the fact that EMFs cause an oxidative
stress that is, increase in the activity, concentration and lifetime of free radicals [21]. Electromagnetic fields
affect biological systems as the kind of abiotic stress [7].
In plants affected by stress, a response is induced by changes in the plant metabolism, growth and general
development [15]. Many studies have reported the effects of magnetic fields on variety of agriculturally
important plants.
Alexander et al.[2] found that seed germination of onion and rice is accelerated if exposed to a weak
electromagnetic field for 12 h and further, the seedlings showed significantly increased fresh and dry weight.
Bitonti and collaborators showed that exposure of Zea mays seedlings to a continuous electromagnetic field
(DC) for 30 h induced stimulation by about 30% in the rate of root elongation compared with the
controls[4].Oxidative stress was induced when Duckweed (Lemna minor L.) exposed to EMFs for two hours
In meristematic cells in Allium ceppa which seeds were exposed to EMFs, mitotic index and mitotic
aberration such as lagging chromosomes, vagarant, chromosome stickness and distributed anaphase was induced
(Khalec et al., 2009). EMFs also alter gene expression, protein biosynthesis, enzyme activity and cell
reproduction [16].
Lepidium sativum L. (Garden cress) is an annual herb, belonging to Brassicaceae family. It is a fastgrowing, edible plant botanically related to watercress and mustard and sharing their peppery, tangy flavor and
aroma. Seeds, leaves and roots are economically important. This important green vegetable consumed by human
beings, most typically as a garnish or as a leaf vegetable [24].
This study considers the effects of EMFs as abiotic stress on the seed germination, seedling development,
mitotic index, some physiological characters and leaf peroxidase activity as the antioxidant enzyme.
MATERIALS AND METHODS
Electromagnetic field exposure:
Exposure to EMFs was performed using a locally designed EMF generator. The electrical power was
provided by a 220 V AC power supply (ED-345BM, China) with a variable voltage, current and fixed frequency
Corresponding Author: Elham Bagheri Abyaneh, Department of Biology, Faculty of Biological Sciences, North-Tehran
Branch, Islamic Azad University, Tehran, Iran.
E-mail: [email protected]
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Advances in Environmental Biology, 8(4) March 2014, Pages: 980-984
(60 Hz). This system consisted of one handmade coil, cylindrical in form, made of polyethylene 12 cm in
diameter and 50 cm in length. The coil was not shielded for electrical field and the seeds were exposed to both
magnetic and electric fields generated by the coils.
Seeds preparation and treatment:
Lepidium sativum L. were supplied by Pakan bazr institute, which guarantees high seeds quality and
homogeneity. The healthy uniform seeds were selected and divided in to wet and dry seeds groups. Three
replicates were used in the experiment with 30 seeds in each treatment. In the case of wet treatment, the seeds
were soaked in distilled water for 7 and 14 hours and then placed in the middle of a horizontally fixed coil. The
wet and dry seeds were exposed to EMFs by a magnitude of 3.7 mT, for 30 and 60 min. On the first day of
treatment the percentage of germination was measured (Seed germination was completed for all of the
treatments in the first day). Fourteen-day-old plants were then used for measurement of growth parameters (leaf
fresh weight, shoot and root length, number of lateral roots) and chlorophyll a, b, carotenoid leaf protein content
and leaf peroxidase activity and three day old plants were used for measurement of mitotic index.
Mitosis index:
The 3 day old root meristem tissue samples from germinated seeds (using only roots reached about
maximum 5 mm length) were used to prepare microscope slides. For preparation of all dividing stages, root tips
were fixed in Carnoy’s fixative without pre-treatment. Preparation of slides from the fixed root tips was done
following acetocarmine squash technique. The cell mitotic index were examined and counted microscopically
on squashes. The mitotic index is able to give the percentage of dividing cells in every sample:
M. I%= (total cells in division/ total cells analyzed) × 100
Determination of photosynthetic pigments:
Rate of photosynthetic pigments estimated according to the method of Lichtenthaler et al., [14]. Fresh
leaves (0.1 g) were homogenized in 80% acetone and centrifuged at 10,000×g for 10 min. The supernatant was
subjected to spectrophotometeric analysis of 646, 663 and 470 nm respectively. Chlorophyll a, chlorophyll b,
and carotenoid content was determined and expressed in mg/ g FW.
Chl. a, Chl. b and carotenoid contents were calculated using the following formulas:
Chl. a = (12.21 (A663) - 2.81 (A646)) × volume of supernatant (ml) /1000× sample weight (g).
Chl. b = (20.13 (A646) - 5.03 (A663)) × volume of supernatant (ml) / 1000×sample weight (g).
Car. = [(1000A470 (1000A470 - 3.27[chl a] - 104[chl b])/227] × volume of supernatant (ml) /1000 × sample
weight (g).
Protein content assay:
Frozen leaves (0.5 g fresh weight) were homogenized in 5 ml Tris- Glycine buffer (pH 8.3). The
homogenate was then centrifuged at 12000× g for 10 min. All operations were performed at 4 °C. Protein
contents were determined by the method of Bradford (1976) using bovine serum albumin (BSA) as a standard
[5].
Peroxidase activity:
The peroxidase activity was measured in a reaction mixture consisting of acetate buffer (0.2 mM, pH 4.8),
hydrogen peroxide (0.1 mM), benzidine (0.04 M) and enzyme extract. Enzyme activity was measured by a
spectrophotometer (Genway Genova) at 530 nm [11].
Statistical analysis:
All of the experiments were carried out with at least three independent repetitions. Data were then evaluated
with one-way analysis of variance combined with Tukey’s multiple-comparison test (Sigma Stat, SPSS Science,
Chicago, IL). The differences between each treatment in comparison with the others were considered significant
at the P < 0.05 level figures. The results were expressed as mean values ±standard error.
Results
Seeds germination:
Seed germination speed was significantly different among electromagnetic fields treatments. As a whole,
electromagnetic treatments obviously increased germination in different electromagnetic exposure periods, but
the differences were greatest when the seeds were soaked in water for 7 and 14 hours and exposed to
electromagnetic field for 1 hour. At higher duration, germination was higher (Table 1).
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Advances in Environmental Biology, 8(4) March 2014, Pages: 980-984
Table 1: The effect of low frequency electromagnetic fields on seeds germination of Lepidium sativum L.
Seed condition
EMF exposure time
18th hour
20th hour
Control
30±5.77a
36.67±6.66a
Dry
30 min
33±3.33a
53.33±8.81abd
Dry
60 min
63.33±8.81abc
80±10bcde
7 h wet
30 min
40±5.77ab
66.67±3.33abcde
7 h wet
60 min
73.33±3.33bc
90±5.77cde
14 h wet
30 min
60±10abc
73.33±8.81de
14 h wet
60 min
76.67±8.81c
100±0e
Data are means± SE, n = 3. Different letters refer to significant differences according to Tukey test (P < 0.05).
22nd hour
70±5.77a
76.67±8.81abc
93.33±6.66abc
86.67±8.81abc
100±0 bc
93.33±3.33abc
100+0 c
Mitotic index, root length and number of lateral roots:
EMFs increased the mitotic index, root length and the number of lateral roots. The highest value of mitotic
index belonged to dry and wet pretreated seeds with 60 minutes exposure time. The highest root length occurred
in plants grown from 7 and 14 hour wet pretreated seeds with 3.8 mT for 60 minutes. EMFs exposure also
caused significant differences in the mean of lateral roots. In this case the most number of lateral roots occurred
in the wet and dry pretreated seeds with 60 minutes of EMFs exposure time in compared to control plants (Table
2).
Shoot length:
The effect of EMFs on the shoot system growth was highly perceptible. EMFs increased the shoot length.
There was significant difference for all treated samples compare to control plants. The wet and dry treated seeds
with 60 minutes exposure time had longer shoot length compare to control group (Table 2).
Wet and dry weight:
Electromagnetic fields increased dry and wet weight of Lepidium sativum L.. The plants grown from 7 and
14 hours wet pretreated seeds with 60 minutes of EMFs exposure time showed the most level of the fresh and
dry weight that had the significant difference compare to control, but there was no significant difference
between control and dry treated seeds (Table 2).
Table 2: The effect of low frequency electromagnetic fields on seedlings growth, fresh and dry weight of Lepidium sativum L
Seed
EMF
Mitotic index
Root lenght
Number of lateral
Shoot lenght
condition
exposure
(cm)
roots
(cm)
time
control
2.36±0.06a
3.77±0.22a
4.60±0.37a
1.6±0.02a
Dry
30 min
2.54±0.05abce
3.81±0.41ab
4.97±0.58a
2.33±0.17bcdef
Dry
60 min
2.7±0.03bcde
4.37±0.08abc
8.23±0.44bcd
2.46±0.14cdef
7 h wet
30 min
2.61±0.05cde
4.18±0.11abc
6.23±0.38abcd
2.26±0.8def
7 h wet
60 min
2.82±0.03de
4.91±0.27bc
7.90±0.66cd
2.62±0.18ef
14 h wet
30 min
2.72±0.02e
4.33±0.21abc
6±0.24abc
2.38±0.1f
14 h wet
60 min
3.08±0.04f
5.2±0.13c
8.73±0.80d
3.33±0.03g
Data are means± SE, n = 3. Different letters refer to significant differences according to Tukey test (P<0.05).
Fresh weight
(mg)
Dry weight
(mg)
85.91±7.745a
92.20±10.25ac
101.1±8.163abc
122.3±4.768abc
136.9±4.729bcd
127.8±8.852cd
169.5±7.075d
4.92±0.62a
6.240±0.2031ad
7.01±0.67abd
12.92±2.92bcde
13.65±1.27cde
12.13±0.88de
15.19±0.77e
Photosynthetic pigments:
The results of the present study indicated that there was no significant difference in chlorophyll a and
chlorophyll b content in plants grown from wet and dry pretreated seeds in comparison with control plants, but
this difference was significant in caretonoid concentration. Wet treated seeds had the most carotenoid
concentration compare to the other groups and control (Table 3).
Protein content:
Electromagnetic fields increased protein content of Lepidium sativum L.. Results showed that protein
content increased in the treated plants in comparison with the control group. Treated seeds with 1 hour exposure
time at 3.8 mT had more protein content than those with 0.5 hour exposure time and control (Table 3).
Table 3: The effect of electromagnetic fields on Chlorophyll a, Chlorophyll b, carotenoid, protein content and peroxidase activity of
Lepidium sativum L.
Seed
EMF
Chlorophyll a
Chlorophyll b
Carotenoid
Protein content
Peroxidase
condition
exposure
(mg/g FW)
(mg/g FW)
(mg/g FW)
(mg/ g FW)
activity
time
(OD /min. g FW)
Control
0.48± 0.02a
0.23± 0.01a
0.22±0.02abcdef
1.87±0.3a
1.5±0.23a
Dry
30 min
0.56± 0.04a
0.31± 0.04a
0.22± 0.02abcdef
2.27±0.09a
2.9±0.45a
Dry
60 min
0.58± 0.01a
0.33± 0.02a
0.23± 0.008bcdef
2.56±0.27ac
5.78±0.08abc
7 h wet
30 min
0.6±0.02a
0.30± 0.02a
0.24± 0.02 cdef
2.12±0.24a
5.5±1.32abc
7 h wet
60 min
0.64±0.008a
0.34± .007a
0.26± 0.006def
3.98±0.22bcd
14 h wet
30 min
0.61± 08a
0.31±0.03a
0.26±0.002ef
3.71±0.36cd
14 h wet
60 min
0.62± 0.01a
0.35±0.02a
0.27±0.0099f
4.87±0.22d
Data are means± SE, n = 3. Different letters refer to significant differences according to Tukey test (P < 0.05).
10.17±0.97bcd
11.20±0.91cd
12.77±2.54d
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Peroxidase activity:
Peroxidase activity increased in the treated plants in comparison with the control group. Maximum and
minimum leaf peroxidase activities were observed in the control and 14 hours wet pretreated seeds with 1 hour
exposure time, respectively (Table 3).
Discussion:
Results obtained for Lepidium sativum L. was according with other studies about the influence of magnetic
field on several seed germination and plant growth which reveal that magnetic treatment produces: an
improvement of percentage and rate of germination of exposed seeds. Florez et al. 2007 reported the positive
effects of magnetic field treatments on germination rate and growth. The possible reason for intensification of
germination may be increasing metabolism in irradiation seeds and increase in substance consumption and more
water absorption under effect of EMFr [22].
The results showed that the effect of electromagnetic fields on Lepidium sativum L. growth in terms of root
length, number of lateral roots and mitotic index was more than control. Wet condition with 1 hour exposure
time increased growth and development of roots. Growth rate is regulated by the combined activity of two
linked processes, expansion and cell production (Beemster Gerrit and Baskin Tobias, 1998). We found that
magnetic fields caused significant increase in the cell division in root meristem cells. Therefore electromagnetic
fields probably enhance the root length by stimulating the tip root cells division.
Leaf protein content was higher in EMFs pretreated plants. Magnetic application could induce the protein
synthesis in plants and it might be the reason of more accumulation of protein in leaf which is consistent with
the findings of this study. Other study has also reported higher protein content in magnetic field exposed
Cucumis sativum seedlings [19].
Fresh and dry biomass weight of plants grown from exposed grains were increased significantly compare to
the control plants, which may be due to higher rate of protein synthesis in pretreated plants.[10]. indicated that
electromagnetic fields increased enzymes activity and protein contents and led to enhance biomass of plants.
Farzpour et al., also reported that electromagnetic fields caused significant increase in dry and wet weight of
Valerian seedlings.
Our results demonstrated that electromagnetic fields increased carotenoid content and peroxidase activity
especially in wet and dry pretreated seeds with 60 minutes electromagnetic exposure time. As the exposure time
increased, the rate of carotenoid and peroxidase activity enhanced, but electromagnetic fields did not affect
chlorophyll a and chlorophyll b content. Similar experiment was reported electromagnetic fields of low intensity
(1 mT) caused significant increase in carotenoid content of Satureja bachtiarica L. [20].Recent findings suggest
that magnetic field may extend the lifetime of the free radical and its potential of damage could be exaggerated
[6]. Carotenoids constitute the first line of defense against 1O2 toxicity. They are able to quench this ROS and
also directly quench triplet chlorophylls, the major source of 1O2 in plant leaves [8,12,27].Therefore increase in
carotenoid content probably caused the stability of chlorophyll a and chlorophyll b content. Another main
protective role against free radicals is increase of the activity of ROS scavenging enzymes, e.g., SOD, CAT, and
PO [23]. Scavenging of H2O2 is conducted by peroxidase and other H2O2-consuming enzymes. Therefore, a
higher concentration of carotenoids and PO activity suggest the responses of EMFs pretreated seedlings to
oxidative stress and free radicals to protect plants against ROSs (reactive oxygen species).
Conclusion:
The exposure of low electromagnetic fields has elicited detectable responses on Lepidium sativum L. in
their early ontogenetic stages: the significant stimulatory influence on plants growth was gained, the average of
mitotic index, root and shoot length values, fresh and dry tissue mass, carotenoid and protein content and
peroxidase activity, being enhanced for all exposure durations and as the exposure time increased the amount of
these parameters enhanced in plants grown from dry and wet pretreated seeds. Electromagnetic fields also had
the slight stimulatory influence (EMFs increased chlorophyll a and b) on the chlorophyll a and b that was not
significant.
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