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

water treatment of seeds had been reported to improve the water productivity

in the seedlings of eggplant (Solanum melongena L.), tomato (Solanum lyco­

persicon L.) and faba beans (Vicia faba L.) by 1.65, 1.70, and 1.88 times, and

thereby, the water savings of 11%, 14.2% and 13.5% respectively (Kareem,

2018).

Exposure to a magnetic field causes several changes at the intracellular

level like the density of Ca²⁺ and other ionic substances. The Ca²⁺ ions play

a very important role in several aspects of plant responses-like its growth,

photosynthetic activity, mineral uptake, water, and reserve food transporta­

tion. The exposure of sunflower (Helianthus annuus) seedlings to a vertical

magnetic field of 0.02 mT strength promoted seedling growth parameters

like root and shoot fresh weights (Fischer et al., 2004). Pre-sowing magnetic

field exposures also resulted in the enlargement of epicotyl cells and the

development of greater osmotic pressure in the seedlings. Further, low

MF exposure causes the development of some ultrastructural peculiarities

like higher buildup of lipid bodies, increased formation of different lytic

compartments viz., vacuoles, cytosegresomes, and paramural bodies, and a

subsequent decrease in the phyto-ferritin content in plastids. On the other

hand, the mitochondria show most sensitivities such as the size and amount

of mitochondria in cells is increased, the matrix of mitochondria get electro­

transparent and reduction in cristae under exposure to low MF. Further, it has

been reported that low MF exposure results in disruption of different meta­

bolic systems with the Ca²⁺ homeostasis and this, in turn, leads to change in

root cell ultrastructure (Belyavskaya, 2001).

Artificial shielding of geomagnetic field results in a substantial reduction

in the cell numbers accompanied by higher DNA content in the meristematic

region of shoot and root of onion (Allium cepa). Further, the formation of

giant cells with large nuclei due to the fusion of normal nuclei, and binuclear

or tetranuclear cells from mitosis without undergoing cytokinesis have been

reported under low MF exposure (Nanushyan & Murashov, 2001). A recent

study on the combination of magneto-priming and chemical priming on

onion (Allium cepa) revealed that chemical priming with ascorbic acid (AsA)

(50 mg L^–1) or zinc sulfate (500 mg L^–1) and 450 gauss of magneto-priming

resulted in enhancement of growth parameters when the priming agents were

used otherwise. The combination of AsA and magneto-priming for 24 hours

also enhanced the germination velocity, dry weight, and vigor index of seed­

lings with reduced mean germination time, increased field emergence or total

amino acids. Likewise, the combination of zinc sulfate and magneto-priming