STATIC MAGNETIC FIELD INFLUENCE ON SOME PLANT GROWTH*
M. RACUCIU1, GH. CALUGARU2, D.E. CREANGA3
1
“Lucian Blaga”, University of Sibiu, Romania
Technical University “Gh. Asachi”, Iasi, Romania
3
“Al. I. Cuza” University, Iasi, Romania, e-mail: dorinacreanga@yahoo.com
2
Received December 21, 2004
Young plantlets of maize (obtained from caryopsides with uniform genophond
let to germinate and growth within an Angelantoni scientifica climatic room) have been
cultivated in the presence of static magnetic field in order to observe the dynamics of
plant length. Average values and standard deviations have been daily evaluated.
Stimulatory effect of the magnetic field ranging between 50 mT and 250 mT was
noticed with a saturation tendency at the 5th, 7th and 9th day. Linear correlations were
found to describe the average length dependence on the magnetic energy. After 11 days
the total fresh substance mass was weighted as well as the dry substance mass.
Logarithmic dependence of the dry substance mass on the magnetic energy was
evidenced. The application of t-test revealed the effect of certain non-homogeneity of
the magnetic sources.
Key words: Zea mays, permanent magnets, growth stimulation.
1. INTRODUCTION
The biological effects of static magnetic field exposure represented an
interesting research theme in the bioelectromagnetism field. After exposure to
static magnetic field E.coli (K-12 lon mutant) cells lost capacity for division and
grow as filaments, unable to form the colonies on the solid media (1). It was
demonstrated that a magnetic field can actually enhance the efficiency of DNA
repair in E.coli (2) but exposure of cultured mammalian cells to electric, magnetic,
or combined electric and magnetic fields did not affect the rate of repair of DNA
single strand breaks induced by hydrogen peroxide (3). Various bacterial strains
that have been exposed to a homogeneous magnetic field of 1 Tesla, presented no
mutagenic or lethal effects, the activity of the bacterial enzyme beta-galactosidase
*
Paper presented at the 5th International Balkan Workshop on Applied Physics, 5–7 July
2004, Constanţa, Romania.
Rom. Journ. Phys., Vol. 51, Nos. 1–2, P. 245–251, Bucharest, 2006
246
M. Racuciu, Gh. Călugaru, D.E. Creangă
2
being also found as independent of the applied magnetic field (4). The growth of
wheat plantlets in a static magnetic field was stimulated (5) for different exposure
protocols.
In the next, the influence of the magnetic exposure on the maize length and
substance accumulation was investigated.
2. MATERIAL AND METHOD
Caryopsides of Zea mays harvested from a single plant, in order to minimize
the genophond variation have been chosen to compose the samples (25 seeds let to
germinate on watered paper support in a Petri dish constituted a sample). Round
permanent magnets having a 50 mT magnetic induction in their center were placed
under the Petri dishes containing each 25 maize seeds. Five samples have been
arranged using one, two, three, four and respectively five magnets under each dish.
After germination the growth was conducted within a Angelantoni scientifica
climatic room in well controlled conditions of temperature (240C) and illumination
(16 h:8 h light:dark). Magnetic exposure was carried out continuously during 11
days.
Plant individual length was measured with 0.1 cm precision while the sample
weight was measured with 10-5 g accuracy. Plant drying was carried out at 100 0C
in a vacuum oven.
Statistic analysis was accomplished by means of average values, standard
deviations and t-test (two tails, pair type) with the significance criterion of 0.05.
3. RESULTS AND DISCUSSION
In the graphical representations from figures 1-5 the average values of plant
lengths are represented for the 3th, 5th, 7th, 9th and 11th day of growth. The
magnetic exposure can be quantified by means of the total energy dose (as a
function of the magnetic permeability, the magnetic induction and the time):
D=
B2
∆D
.t , where: ∆D = µ0
∆t
2
The stimulatory effect noticed for all exposed samples (corresponding to the
total magnetic induction values of B, 2B, 3B, 4B and 5B with B=50 mT). The
length average values are enhanced almost proportionally to the magnetic induction
- linear regression curves with correlation coefficients (R2) ranging between 0.61
and 0.93 have been found.
cm
Magnetic field influence on some plant growth
day 3
6
5
4
3
2
1
0
y = 0.2533x + 2.159
2
R = 0.6648
1
2
3
4
5
6
magnetic exposure
Fig. 1 – Average length after 3 days of growth
(1,...,6 meaning magnetic induction equal to 0, B, 2B,..., 5B).
day 5
8
cm
6
4
2
y = 0.336x + 3.1431
R2 = 0.9302
0
1
2
3
4
5
6
magnetic exposure
Fig. 2 – Average length after 5 days of growth
(1,..., 6 meaning magnetic induction equal to 0, B, 2B,..., 5B).
day 7
cm
3
7
6
5
4
3
2
1
0
y = 0.1696x + 4.311
2
R = 0.6188
1
2
3
4
5
6
magnetic exposure
Fig. 3 – Average length after 7 days of growth
(1,...,6 meaning magnetic induction equal to 0, B, 2B,..., 5B).
247
248
M. Racuciu, Gh. Călugaru, D.E. Creangă
day 9
8
cm
6
4
y = 0.1363x + 5.1077
R2 = 0.6813
2
0
1
2
3
4
5
6
magnetic exposure
Fig. 4 – Average length after 9 days of growth
(1,...,6 meaning magnetic induction equal to 0, B, 2B,..., 5B).
day 11
10
8
cm
6
4
y = 0.1489x + 6.0359
R2 = 0.7249
2
0
1
2
3
4
5
6
magnetic exposure
cm
Fig. 5 – Average length after 11 days of growth
(1,...,6 meaning magnetic induction equal to 0, B, 2B,..., 5B).
8
7
6
5
4
3
2
1
0
day 3
day 5
day 7
day 9
day 11
1
2
3
4
5
6
magnetic exposure
Fig. 6 – Comparative picture of the correlation between the plant
length and the magnetic induction.
4
5
249
Magnetic field influence on some plant growth
8
cm
7
6
control
5
B
2B
4
3
3B
4B
2
1
2
3
3
4
5
days
5 7 9
11
5B
Fig. 7 – The growth dynamics for different magnetic induction values.
g
0.9
water
dry mass
y = 0.0156Ln(x) + 0.1246
0.2
2
R = 0.8986
0.8
0.15
0.7
0.1
0.6
0.05
0.5
g
fresh mass
0
1
2
3
4
5
6
magnetic exposure
cm
Fig. 8 – The fresh substance mass and the water accumulation
(1,...,6 meaning magnetic induction equal to 0, B, 2B,..., 5B).
7.2
7
6.8 y = 4.422x + 3.2442
2
R = 0.9324
6.6
6.4
6.2
6
0.5
0.6
0.7
0.8
0.9
g/cm
Fig. 9 – The correlation between plant length and total fresh substance mass at the 11th day.
250
M. Racuciu, Gh. Călugaru, D.E. Creangă
6
The rather high standard deviation values that affected the correlation
coefficient may be generated by the non-homogeneity of the magnetic exposure
since the magnetic induction is slightly decreased from the center of the round
magnet (the center of the plantlets arrangement within a Petri dish) and the its
contour. Consequently, the comparison between the control (non-exposed) sample
and the magnetic exposed samples, carried out by means of the t-test revealed
statistically significant differences only for some situations (Table I).
Table I
The values of the statistical significance values according to T-test
B
2B
0.249637
0.112455
0.177984
0.604081
0.166994
3B
0.090091*
0.013504*
0.398944
0.371439
0.320937
4B
5.26822E-06*
0.00029075*
0.130695183
0.165732033
0.175715493
5B
0.001178*
0.000117*
0.11205
0.168299
0.047496*
Day
8.42381E-05*
1.5737E-06*
0.170404745
0.160889381
0.001776743*
3
5
7
9
11
*-statistically significant according to the threshold of 0.05.
In Figure 6 a comparative representation of the experimental data is given.
The influence of the magnetic induction increasing was leading to a saturation
tendency for the last three samples (3B, 4B and 5B) at the 5th, 7th, and 9th days.
The control does not appear to be higher than the exposed samples in all situations
as reflected also in the graph from figure 7, where the curves corresponding to the
growth dynamics of every sample are not parallel.
In Figure 8 the fresh mass of the plants from every sample is represented
together with the dry mass and the water content corresponding to the 11th day of
growth. A certain diminution was noticed in the fresh substance mass as well as in
the water content for the magnetic induction of 2B. The dry substance mass was
found to correlate logarithmically on the magnetic induction. In Figure 9 the linear
approach of the correlation between the average length and the mass per length was
represented, outlying the clear stimulatory effect of the magnetic exposure at the
individual level.
These results may be interpreted taking into account the magnetosensitivity
as ubiquitous feature of the organisms living in the magnetic field of the Earth. The
results obtained for the relatively low values of the magnetic induction used in this
experiment can not be extrapolated for other ranges of values; however they can
have their relevance if one consider the non-homogeneity of the environmental
magnetic field as well as the variations generated by the artificial sources of
magnetism.
Further experiments and investigation techniques are intended in order to get
a deeper insight in the plant magnetosensitivity and putative biotechnological tools
could be designed on the basis of the magnetic exposure.
7
Magnetic field influence on some plant growth
251
4. CONCLUSIONS
Young plants of maize (a significant cereal for many human communities and
aliment industries) are able to respond to the magnetic field ranging between 50
and 250 mT. Plant lengths are higher for all exposed samples as it was record for
the first 11 days of growth. The relatively high standard deviations may be taken as
an indication upon the plantlet sensitivity to the non-homogeneity of the magnetic
exposure since genophond non-uniformity was minimized. The accumulation of
dry substance mass was enhanced logarithmically to the increase of the magnetic
induction.
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