106

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

priming techniques are used by various researchers to combat temperature

stress at later stages of growth in various crops (Thakur et al., 2019). Afzal

et al. (2015) reported that maize treated with magnetic field of strength 150

mT increased chilling tolerance, plant growth, chlorophyll, total phenolics,

gaseous exchange, seed protein, and oil content. In radish, magnetic field

treatment (400 A/m) increased polar lipids under light and chilling stresses

(Novitskaya et al., 2010). However, the effect of magneto-priming may

generate interesting information if focused on the ‘stress memory’ response

in relation to activation of gene network during priming and the mechanism

of tolerance in plants on subsequent exposure to extreme temperatures.

4.2.4 HEAVY METAL STRESS

Magneto-priming may be used to ward off the deleterious effects of heavy

metal stress by enhancing the seed germination, seedling vigor, rate of photo­

synthesis, biomass accumulation and crop productivity (Prajapati et al., 2020).

Chen et al. (2011) reported that SMF (600 mT) alleviated the toxic effects of

cadmium salts through increasing the photosynthetic rate, NO concentration

and NOS activity and reducing the lipid peroxidation in mungbean seedlings.

Pretreatment of SMF (200 mT for 1 h) to soybean ameliorated arsenic toxicity

in relation to growth, photosynthesis, and water uptake (Fatima et al., 2020).

In this study, SMF-pretreatment caused an increase in leaf area with larger

thickness of midrib/minor veins along with improved photosynthetic perfor­

mance in contrast to un-primed seeds under As(V) stress.

Iron uptake in plants is dependent on the redox reaction catalyzed by

ferric reductase activity and the exposure to magnetic field alters the rates of

redox reaction in plants (Bertea et al., 2015). Islam et al. (2020) suggested

a role of the geomagnetic field in the uptake and maintenance of iron in the

plant cells through increased activity of ferric reductase. These findings can

be effectively utilized for phytoremediation of heavy metals like Fe through

magneto-priming seeds before sowing in contaminated soils.

4.2.5 UV-B STRESS

Higher levels of biologically effective UV-B radiation traverse through

the atmosphere due to high concentrations of ozone-depleting substances,

changing climatic conditions, and altered land-use patterns (Laube et al.,

2014; Bornman et al., 2015). The UV-B radiations have deleterious effect

on important biomolecules (Kataria et al., 2014a; Parihar et al., 2015) and