Sweet pepper (Capsicum annum L.) is one of the most important vegetables
and popular crops grown in many countries including Egypt. Sweet pepper occupied
108026 feddan. (45389 ha) in Egypt during 2009 with an average of 7.4 ton per
feddan. (AOAD, 2009). Its fruits have high nutritional
values, as they are a very rich source for vitamin A and C (Elwan
and El-Hamahmy, 2009; Rajput and Poruleker, 1998).
Enhancement of the productivity and quality of sweet pepper is usually dependent
on many factors that influence the plant growth throughout the growth period
as well as improving agricultural treatments.
Different chemical and non-chemical methods have been applied to improve crop
yield and quality, one of which is magnetic field (Jinapang
et al., 2010). It has been reported that magnetic field affects plant
growth and development processes such as seed germination and seedling growth
(Aladjadjiyan, 2002). Furthermore, magnetic field may
alter the characteristics of cell membrane and cell reproduction and may cause
some changes in cell metabolism and various cellular functions including gene
expression, protein biosynthesis and enzyme activities (Atak
et al., 2003). Several studies have reported the influence of magnetic
field on seed germination and vegetative growth of vegetable crops such as mung
bean (Huang and Wang, 2008), tomato (De
Souza et al., 2005, 2006), snow pea and chickpea
(Grewal and Maheshwari, 2011) and peas (Eskov
and Rodionov, 2010).
This study was designed to investigate the influence of magnetic field on seed
germination, vegetative growth, yield and yield quality of sweet pepper cultivated
under Egyptian soil conditions.
MATERIALS AND METHODS
Magnetic funnel: A magnetic funnel (Brand name: Magnetic Technologies L.L.C.,
Model No. MFL01, Dubai, U.A.E.) was used. Two cassettes with ceramic magnets
are located inside the cylindrical part of the magnetic funnel. Length of each
cassette is 75 mm, there are seven magnets installed inside of each cassette
with intervals. North poles of magnets of one cassette are located opposite
south poles of magnets of other cassette. Maximal magnetic induction along axis
cylindrical part of the magnetic funnel is 57-60 mT (millitesla) between magnets
in each pair and 4-6 mT in the intervals between the pairs of magnets.
Plant material and germination experiment: Seeds of sweet pepper (cv.
California Wonder) were purchased from Tanta, Egypt. The seeds were divided
to four groups and each group contains 10 seeds in 10 replications. Seeds in
the first group were passed through the magnetic funnel to be magnetized and
then the seeds were placed in petri dishes (9 cm) containing Whatman No.1 filter
paper soaked with normal distilled water (non-magnetized water). Seeds in the
second group (non-magnetized seeds) were soaked in magnetized distilled water
that was previously passed through the magnetic funnel. In the third group,
magnetized seeds were soaked in magnetized distilled water. In the fourth group,
non-magnetized seeds were soaked in non-magnetized distilled water to serve
as a control. Seeds in all groups were left to germinate at room temperature
(25±2°C) for 14 days to measure the percentage of germination according
to Scott et al. (1984) and Bartlett
Experimental design: The experiment was carried out in duplicate at
the experimental farm of the Faculty of Agriculture, Tanta University during
2011 and 2012.
Seedbed experiment: The seeds were sown in seedling trays in a plastic
greenhouse on 16th and 17th January 2011 and 2012, respectively. Treatments
in the seedbed were arranged in a complete randomized block design with three
replications and the seeds were divided to four groups as mentioned above. The
first group contained magnetized seeds irrigated with non-magnetized water.
The second group contained non-magnetized seeds irrigated with magnetized water.
The third group contained magnetized seeds irrigated with magnetized water,
while the fourth group contained non-magnetized seeds irrigated with non-magnetized
Field experiment: Seedlings from each treatment were transplanted to
the open field on 6th and 8th of March 2011 and 2012, respectively at 30 cm
apart in one side of the ridges. The plot area was 11.2 m2, which
contained four rows with 4 m in length and 70 cm in width. Treatments in the
field were arranged in a complete randomized block design with three replications.
Normal cultural practices were carried out as recommended for the conventional
pepper planting according to instructions of Egyptian Ministry of Agriculture.
During this period, non-magnetized water was provided to all four treatments.
|| Chemical analysis of the experimental soil
The soil in the plots was a clay loam soil with organic matter 1.5%, pH 7.25
and EC/25°C 4.03 mmhos cm-1. Table 1 provides
information on the soils chemical analysis determined according to Ryan
et al. (1996).
Seedlings growth parameters: During the seedbed period, 10 seedlings
per treatment were sampled at 50 days post-sowing to measure seedling height,
number of leaves per seedling, seedling fresh and dry weight and seedling leaf
Vegetative growth traits: Five plants from each plot were randomly sampled
at 90 days after transplanting to determine plant height, number of branches
per plant, number of leaves per plant, fresh and dry weight per plant and leaf
area per plant.
Flowering growth traits: Five plants from each plot were randomly selected
and labeled to determine the days after transplanting to 25% flowering, number
of flowers per plant and percentage of fruit set.
Yield parameters: Ten representative marketable fruits from each treatment
at the middle of harvesting season were collected and used for determination
of yield parameters including fruit fresh and dry weight, fruit number per plant,
fruit length, fruit diameter and pericarp thickness. In addition, fruits produced
from each plot were harvested and used to determine early and total marketable
fruit yield. Early marketable yield was determined from the first three harvestings.
Chemical composition of leaves: Contents of chlorophyll a and b, caroteniods,
N, P and K in the leaves of sweet pepper were determined according to the Association
of Official Analytical Chemists International (AOAC, 1995).
Chemical composition of fruits: Concentrations of vitamin C, nitrate
(NO3), Total Soluble Solids (TSS), titratable acidity, N, P, and
K in the fruits of sweet pepper were determined according to the Association
of Official Analytical Chemists International (AOAC, 1995).
Statistical analysis: Data were analyzed by MSTATC computer software
program adopted by Bridker (1991) using ANOVA with the
Least Significant Difference (LSD) at the 0.05 probability level.
Seed germination: Figure 1 shows the percent germination
rate of pepper seeds treated with magnetic field. Germination of all treated
seeds began one day earlier than that of non-treated seeds. After the 14th day
of soaking, 83.3, 84.7 and 90.3% germination were achieved in magnetized seeds,
magnetized water and magnetized seeds+water, respectively; while, it was 62.3%
in non-treated seeds (LSD = 5.14 at 5%). Highest germination rate was achieved
for magnetized seeds that were soaked in magnetized water rather than magnetized
seeds soaked in non-magnetized water or non-magnetized seeds soaked in magnetized
water. However, no significant difference was observed between the germination
rate of magnetized seeds and magnetized water when used separately. Germination
percentage increased by 33.7, 35.8 and 44.9% over control in magnetized seeds,
magnetized water and magnetized seeds+water, respectively.
Seedlings growth: As shown in Table 2, growth of all
seedlings produced from treated seeds was significantly promoted than those
produced from non-treated seeds in both 2011 and 2012 seasons. As for instance,
seedling height increased significantly by 21.2, 29.3 and 47% in magnetized
seeds, magnetized water and magnetized seeds+water, respectively in 2011, while
the increase was by 21.1, 28.1 and 45%, respectively in 2012.
||Effect of magnetic field on percent germination rate of sweet
pepper seeds, Values are expressed as the mean (n = 10), LSD for germination%
= 5.14 , MS: Magnetized Seed; MW: Magnetized Water; MSW: Magnetized Seed+Water
|| Effect of magnetic field on growth of sweet pepper seedlings
|Values are means of 3 replications
Likewise, seedling leaf area increased by 15.2, 29.5 and 50.6% in treated seedlings
in 2011 and by 21.2, 35.8 and 56.6% in 2012. This effect was more positive when
seeds and water were both magnetized. Generally, no significant differences
were found in the growth parameters of the seedlings produced from magnetized
seeds only and those produced from magnetized water only.
Vegetative growth traits: Table 3 summarizes the values
of vegetative growth traits of pepper plants affected by magnetic field in seasons
of 2011 and 2012. Values of vegetative growth were significantly higher in treated
plants than those in non-treated plants in both seasons. Reported values were
significantly superior in the plants generated from magnetized seeds that were
irrigated with magnetized water. For example, 11, 12, 14.1, 21.8, 12.2 and 23.5%
increase were recorded in the plant height, number of branches per plant, number
of leaves per plant, fresh and dry weight per plant and leaf area per plant,
respectively for pepper plants generated from magnetized seeds+water treatment
in 2011 compared to the non-magnetized treatment. While in the 2012, same traits
increased by about 12.4, 10.2, 11.6, 12.6, 9.2 and 22.5%, respectively.
Flowering growth traits: Table 4 shows the flowering
traits of pepper plants influenced by magnetic field. Although magnetic field
had no significant effect on number of flowers per plant and fruit set percentage,
it significantly shorted the period to 25% flowering in both seasons.
|| Effect of magnetic field on the vegetative growth traits
of sweet pepper
|Values are means of 3 replications
|| Effect of magnetic field on flowering traits of sweet pepper
|Values are means of 3 replications, NS: Not significant
||Effect of magnetic field on early and total fruit yield of
sweet pepper, Values are expressed as the mean (n = 3), LSD for early yield
= 0.09 and 0.14 for 2011 and 2012 season, respectively, LSD for total yield
= 0.25 and 0.36 for 2011 and 2012 season, respectively, MS: Magnetized Seed;
MW: Magnetized Water; MSW: Magnetized Seed+Water
|| Effect of magnetic field on the yield of sweet pepper
|Values are means of 3 replications, NS: Not significant
Flowering was accelerated by 1.7, 2 and 2.8 days in pepper plants emerged from
magnetized seeds, magnetized water and magnetized seeds+water, respectively
in 2011 compared to the non-magnetized treatment. While in the 2012, magnetized
treatments took 1, 1.3 and 2.4 days shorter to 25% flowering over control, respectively.
Yield parameters: Fruit fresh and dry weight, number of fruits per plant,
early and total marketable fruit yield significantly increased by magnetic field
(Table 5, Fig. 2), while the differences
among fruit length, fruit diameter and pericarp thickness were insignificant.
Total marketable fruit yield increased significantly by about 6.2, 7.4 and 12.1%
in pepper plants generated from magnetized seeds, magnetized water and magnetized
seeds+water, respectively in (2011) compared to the non-magnetized treatment.
In 2012, increase was by 9.2, 10.1 and 14.7%, respectively. This raise is due
to the gain in the fruit fresh weight and the number of fruits per plant.
|| Effect of magnetic field on the chemical composition of sweet
|Values are means of 3 replications, DW: Dry weight, N: Nitrogen,
P: Phosphorus, K: Potassium, NS: Not significant
|| Effect of magnetic field on chemical composition of sweet
|Values are means of 3 replications, FW: Fresh weight, DW:
Dry weight, N: Nitrogen, P: Phosphorus, K: Potassium, Ns: Not significant
Chemical composition of leaves and fruits: Leaf contents of chlorophyll
a and b, caroteniods and P in 2011 season were significantly affected by the
magnetic field, while in 2012; only K concentrations were insignificant (Table
In fruits, the magnetic field significantly increased concentrations of vitamin
C and P but NO3, TSS, acidity, N and K were not affected in 2011
(Table 7). In 2012, concentrations of vitamin C, TSS and P
significantly increased in treated plants, while there were no significant differences
in contents of NO3, acidity, N and K.
Treating pepper seeds and/or irrigated water by magnetic field led to a considerable
enhancement in their germination and subsequently in the growth and yield of
the plants, they produced.
Percent germination rate and seedlings growth of pepper plants were increased
in response to magnetic field (Fig. 1, Table
2). It was previously proposed that magnetic field accelerates seed germination,
seedling growth and activates proteins formation and root development (Aladjadjiyan,
2002; Atak et al., 2003). These effects
may be due to that magnetic field interacts with ionic current in the plant
embryo cell membrane that induces changes both osmotic pressure and ionic concentrations
on both sides of the membrane (Yaycili and Alikamanoglu,
2005). Reina and Pascual (2001) reported that changes
in the ionic fluxes across cell membrane cause alterations in the mechanism
of water uptake, due to the fact that osmo-regulation in embryo cells is controlled
by the ionic transport across the membrane.
Magnetic field also increased vegetative and flowering growth of pepper plants
(Table 3 and 4). The enhancement in vegetative
parameters including plant height, number of branches, number of leaves, leaf
area and leaf fresh and dry weight in the plants derived from the treated seeds
may be due to the increase in the concentration of photosynthetic pigments such
as chlorophyll a and b and caroteniods (Table 6) that provided
greater amount of assimilates available for vegetative growth. This resulted
in a remarkable increase in the vegetative and flowering growth of pepper plants
that produced from seeds treated by magnetic field. It has been stated that
magnetic field caused alterations in the transport properties of cellular plasmatic
membranes, which play an extremely important role in regulating the assimilation
by a cell of the nutrients needed for its functioning (Azharonok
et al., 2009).
Fruit fresh and dry weight, number of fruits per plant, early and total marketable
fruit yield significantly increased by magnetic field (Table 5,
Fig. 2). The considerable improvement in fruit yield parameters
(Table 5) as well as concentration of vitamin C (Table
7) may be resulted from an increase in the number of harvested fruits per
plant and average fruit weight induced by the magnetic treatments. Similar effects
have been reported on mung bean (Huang and Wang, 2008),
tomato (De Souza et al., 2005, 2006),
snow pea and chickpea (Grewal and Maheshwari, 2011)
and peas (Eskov and Rodionov, 2010).
The positive effects of magnetic fields may be a result of bioenergetic structural
excitement causing cell pumping and enzymatic stimulation as they might affect
the regulation of crucial ion mechanisms such as the ATP hydrogen pump, and
possibly the configuration of pivotal proteins (De Souza
et al., 2005). However, the effects of magnetic field on plant growth
still require proper explanation especially for the late growth period such
as flowering and fruiting stages.
The present results indicate that pre-sowing magnetic treatments enhance the
percent germination rate, growth and development of pepper plants and improve
their fruit yield parameters. Furthermore, magnetic field treatment can be considered
as an alternative to chemical and biological methods that are commonly used
in the production of vegetable crops.