104
Subtle Agroecologies
effect was found in treated plants by absorbing more water (23.1%), accumulating more proline
(44.1%) in their leaves and increasing the thickness (17.9%) of their leaves. The treatment 170-mT
MF for 15 min showed the best results (Karimi et al., 2012). Maize (Zea mays L.) plants from
magnetically treated seeds with static MF of 100 and 200 mT for 2 and 1 hour and sown under
greenhouse conditions signifcantly enhanced seedling growth (34.3%) and leaf water status (leaf
water potential (20.6%), turgor potential (46.9%), relative water content (3.5%) and photosynthesis
rate (71.4%)) and lowered the antioxidant defence system (peroxidases (50%) and catalase (66.7%))
of seedlings under soil drought stress (Anand et al., 2012).
Magnetic treatment has been found to provide protection of some plant species against salt stress
without adversely affecting the environment. Pre-treated maize seeds with 200 mT of static MF for
1 hour enhanced germination percentage (16%), germination stress tolerance index (23.2%), seedling vigour (70%), growth parameters (plant height (41%), leaf area (18%) and biomass accumulation
(137%)), photosynthetic pigments content (46%), the rate of photosynthesis (28%) and stomatal conductance (40%), which resulted in improved yield (29%) of maize plants and decreased hydrogen
peroxide (H 2 O 2 ; 32%) under saline conditions (Baghel et al., 2019). A static MF of 35 mT for 0.5 min
caused an increase in all tested germination indexes (36.4%), seedling growth (seedling shoot and
root length (43.6% and 46.8%), seedling dry weight (23%) and seedling vigour (18%)), relative water
content (19.6%), salt tolerance index (10.2%), antioxidant enzyme activity (peroxidase (15.6%), polyphenol oxidase (24%) and chitinase (21.5%)) and feld performance characteristics of barley plants
(40.6%) in combination with water, proline or arginine under different salinity stress levels (324,
2,000, 4,000, 6,000 and 8,000 ppm; Hozayn et al., 2018).
Enhanced germination percentage (10%–19%) and early seedling growth (root and shoot length
(15%–40% and 18%) and vigour indexes (40%)), increased α-amylase and protease activities
(15.4%–56.3% and 4%–10.5%) and increased levels of superoxide radical and hydrogen peroxide
(13.8%–31% and 9.65–13.2%) under different salinity levels (0−100 mM NaCl) were observed in
maize and soybean plants grown from pre-treated seeds with static MF of 200 mT for 1 hour as
compared to control plants (Kataria et al., 2017a).
Sweet corn (maize) plants emerging from magnetically treated seeds using weak (15 mT) or
strong (150 mT) MFs for 6, 12 and 24 hours showed an increase in germination rate and percentage
(5%–25.3%) and plant growth (11.5%–13.4%) and a reduction in proline accumulation (25.8%) by
improving water absorption (25.9%) under NaCl stress (0, 50 and 100 mM). The highest germination rate was obtained by the stronger MF; however, the seedlings were more vigorous after treatment with 15-mT MF (Karimi et al., 2017).
Different experimental results have shown that MF treatment can ameliorate heavy metal toxicity stress in some crops. For example, mung bean seedlings treated with 600-mT MF under
cadmium stress reduced the concentration of malondialdehyde (23.4%–72.2%), hydrogen peroxide (25%–27.8%) and superoxide radical (3.6%–22.1%) and the conductivity of electrolyte leakage
(16.1%–24.6%), while the nitric oxide (NO) concentration (33.3%–39.8%) and nitric oxide synthase
(NOS) activity (13.3%–22.2%), photosynthesis rate (13.4%) and growth parameters (13.3%–22.6%)
increased compared to cadmium stress alone, indicating that MF compensates for the toxicological effects of cadmium exposure and is related to NO signalling (Chen et al., 2011). A stimulating
effect on the growth of spruce (Picea abies) seedlings (69%) was observed for 50-Hz MF of 103 μT
and aluminium solution (in the form of AlCl 3 ) of 100 μM, while slight positive responses were also
found within the range of concentrations between 40 and 160 μM Al 3+ . These results suggest the
importance of the synergistic action of the MF with metal aluminium stressor as well as the existence of physiological windows in addition to the frequency and power ones (Ruzic et al., 2000).
Some results demonstrated an alleviating effect of MF on ultraviolet light stress in plants.
Exposure of sorghum seeds to a static MF of strength 125 mT for 6 hours revealed a signifcant
effect on the percentage of germinated seeds (34.8%), speed of germination (40.5%), seedling length
(45%) and number of leaves (14.4%), while the MF application followed by immediate irradiation
with ultraviolet-C radiation at 254 nm for 30 and 60 min showed no signifcant effect on germination
Subtle Agroecologies
effect was found in treated plants by absorbing more water (23.1%), accumulating more proline
(44.1%) in their leaves and increasing the thickness (17.9%) of their leaves. The treatment 170-mT
MF for 15 min showed the best results (Karimi et al., 2012). Maize (Zea mays L.) plants from
magnetically treated seeds with static MF of 100 and 200 mT for 2 and 1 hour and sown under
greenhouse conditions signifcantly enhanced seedling growth (34.3%) and leaf water status (leaf
water potential (20.6%), turgor potential (46.9%), relative water content (3.5%) and photosynthesis
rate (71.4%)) and lowered the antioxidant defence system (peroxidases (50%) and catalase (66.7%))
of seedlings under soil drought stress (Anand et al., 2012).
Magnetic treatment has been found to provide protection of some plant species against salt stress
without adversely affecting the environment. Pre-treated maize seeds with 200 mT of static MF for
1 hour enhanced germination percentage (16%), germination stress tolerance index (23.2%), seedling vigour (70%), growth parameters (plant height (41%), leaf area (18%) and biomass accumulation
(137%)), photosynthetic pigments content (46%), the rate of photosynthesis (28%) and stomatal conductance (40%), which resulted in improved yield (29%) of maize plants and decreased hydrogen
peroxide (H 2 O 2 ; 32%) under saline conditions (Baghel et al., 2019). A static MF of 35 mT for 0.5 min
caused an increase in all tested germination indexes (36.4%), seedling growth (seedling shoot and
root length (43.6% and 46.8%), seedling dry weight (23%) and seedling vigour (18%)), relative water
content (19.6%), salt tolerance index (10.2%), antioxidant enzyme activity (peroxidase (15.6%), polyphenol oxidase (24%) and chitinase (21.5%)) and feld performance characteristics of barley plants
(40.6%) in combination with water, proline or arginine under different salinity stress levels (324,
2,000, 4,000, 6,000 and 8,000 ppm; Hozayn et al., 2018).
Enhanced germination percentage (10%–19%) and early seedling growth (root and shoot length
(15%–40% and 18%) and vigour indexes (40%)), increased α-amylase and protease activities
(15.4%–56.3% and 4%–10.5%) and increased levels of superoxide radical and hydrogen peroxide
(13.8%–31% and 9.65–13.2%) under different salinity levels (0−100 mM NaCl) were observed in
maize and soybean plants grown from pre-treated seeds with static MF of 200 mT for 1 hour as
compared to control plants (Kataria et al., 2017a).
Sweet corn (maize) plants emerging from magnetically treated seeds using weak (15 mT) or
strong (150 mT) MFs for 6, 12 and 24 hours showed an increase in germination rate and percentage
(5%–25.3%) and plant growth (11.5%–13.4%) and a reduction in proline accumulation (25.8%) by
improving water absorption (25.9%) under NaCl stress (0, 50 and 100 mM). The highest germination rate was obtained by the stronger MF; however, the seedlings were more vigorous after treatment with 15-mT MF (Karimi et al., 2017).
Different experimental results have shown that MF treatment can ameliorate heavy metal toxicity stress in some crops. For example, mung bean seedlings treated with 600-mT MF under
cadmium stress reduced the concentration of malondialdehyde (23.4%–72.2%), hydrogen peroxide (25%–27.8%) and superoxide radical (3.6%–22.1%) and the conductivity of electrolyte leakage
(16.1%–24.6%), while the nitric oxide (NO) concentration (33.3%–39.8%) and nitric oxide synthase
(NOS) activity (13.3%–22.2%), photosynthesis rate (13.4%) and growth parameters (13.3%–22.6%)
increased compared to cadmium stress alone, indicating that MF compensates for the toxicological effects of cadmium exposure and is related to NO signalling (Chen et al., 2011). A stimulating
effect on the growth of spruce (Picea abies) seedlings (69%) was observed for 50-Hz MF of 103 μT
and aluminium solution (in the form of AlCl 3 ) of 100 μM, while slight positive responses were also
found within the range of concentrations between 40 and 160 μM Al 3+ . These results suggest the
importance of the synergistic action of the MF with metal aluminium stressor as well as the existence of physiological windows in addition to the frequency and power ones (Ruzic et al., 2000).
Some results demonstrated an alleviating effect of MF on ultraviolet light stress in plants.
Exposure of sorghum seeds to a static MF of strength 125 mT for 6 hours revealed a signifcant
effect on the percentage of germinated seeds (34.8%), speed of germination (40.5%), seedling length
(45%) and number of leaves (14.4%), while the MF application followed by immediate irradiation
with ultraviolet-C radiation at 254 nm for 30 and 60 min showed no signifcant effect on germination