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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

increased in SMF (200 mT for 1 h) pretreated maize seeds as compared to

untreated seeds under 50 mM NaCl stress (Baghel et al., 2019). SMF helped

in reducing the oxidative damage, owing to the up-regulation of antioxidant

enzymes in stressed plants (Sarraf et al., 2020). The seedlings derived from

magnetic field treated seeds exhibit an increased stem length, stem diameter,

leaf area, and fresh and dry weight under saline conditions (El-Yazied et al.,

2011). Baghel et al. (2016) indicated that SMF (200 milliTesla (mT) for 1

h) pre-treatment significantly increased number and weight of root nodules,

photosynthetic efficiency, biomass, and yield of soybean plants in non-saline

and saline conditions in comparison to untreated seeds. The content of leghe­

moglobin and hemichrome also improved in the root nodules that indicated

that the nodules remained active under salt stress. Seeds of other crops such

as soybean and maize also responded to SMF pre-treatment by alleviating

the salt-induced adverse effects on growth and yield as a result of more

active reaction centers and higher efficiency of electron transport and faster

reduction of electron acceptors in the photosynthetic pathway (Baghel et al.,

2016, 2019; Kataria & Jain, 2019). SMF pre-treatment of the seeds elimi­

nates the need for diverting the metabolic energy towards the detoxification

of ROS produced under salt stress (Kataria & Jain, 2019). Kataria et al.

(2019) reported that static magnetic field treatment (200 mT for 1 h) lowers

the production of hydrogen peroxide (H2O2), antioxidants (dehydroascorbic

acid (DHA), and ascorbic acid (AsA)) and activities of antioxidant enzymes

(SOD, POD, APX, GR) along with higher levels of α-tocopherol in soybean

leaves to facilitate higher growth, photosynthesis, and yield under salinity

stress. Magnetoprimed seeds also showed higher uptake of water in soybean

and maize and lower Na⁺/K⁺ ratio in wheat under saline conditions (Kataria

et al., 2017a, b; Rathod & Anand, 2016). Rathod & Anand (2016) reported

that the sodium exclusion in the tissues of plants from magnetoprimed wheat

seeds may be responsible for enhancing the salt tolerance. Pulsed magnetic

field treatment had a positive effect on the regeneration of soybean calli

under salt stressed condition by enhancing primary and secondary metabo­

lite production (Radhakrishnan et al., 2012; Radhakrishnan & Kumari,

2013). Recently, Kataria et al. (2020a) identified the role of nitrate reductase

(NR) dependent nitric oxide (NO) production in magnetoprimed induced

tolerance towards salt stress in soybean during early seedling growth. They

found that NO scavenger (2-[4-carboxyphenyl]-4,4,5,5-tetramethylimidazo­

line-1-oxyl-3-oxide, CPTIO), inhibitors of enzymes for NO synthesis, NO

synthase (N-nitro-L-Arg-methyl ester, L-NAME) or NR (sodium tungstate,

ST) and of NADPH oxidase (diphenylene iodonium (DPI)) significantly