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

Conversely, magneto-priming is a non-ionizing, physical energy, dry seed

treatment that evades the hydration and dehydration cycle. Both the priming

techniques can alleviate the abiotic stress during seedling emergence and

crop establishment stage, through an array of processes involving upregu­

lation of various signaling pathways and antioxidative systems leading to

production of stress-responsive “savior metabolites.” The evocation of stress

tolerance mechanism is manifested at the plant level as synchrony in seed

germination, early vigor, increased biomass, and yield. The plants can also

respond to reproductive stage stress exposures by using the stress memory

response. In this chapter, we will discuss the various mechanisms governing

the stress response under different abiotic stresses in hydro- and magneto-

primed seeds.

4.1 INTRODUCTION

Plants are exposed to various abiotic factors such as drought, high salinity,

submergence, and extreme temperature, etc., leading to a substantial loss

in crop yield. The exposure to these stress signal leads to activation of

different defense mechanisms, stress signaling, metabolite production, etc.,

resulting in physiological, metabolic, and biochemical changes in plants

(Xiong & Zhu, 2002). These alterations may affect plant performance, yield,

metabolism, and oxidative stress (Jisha et al., 2013). Various efforts have

been adapted to develop plants that can withstand stresses and show minimal

pre- and post-harvest losses in limited agricultural resources (Gust et al.,

2010; Hasanuzzaman & Fotopoulos, 2019). Uniform seed germination, early

seedling growth, and uniform plant stand (Hasanuzzaman & Fotopoulos,

2019) determines yield and plant response to stresses.

Seed priming is an effective method to strengthen the defense line of crop

plants by imparting stress tolerance. Seed priming improves seed germination

and crop stand. In general, seed priming is a physiological procedure of seed

hydration followed by drying that enhances the pre-germinative metabolic

process for faster germination, better growth, and production under normal

as well as stressed conditions. It is a promising low-cost technique to induce

germination, increase growth, and thus the productive ability of crops. In this

process, different priming agents such as water, sugars, nutrients, hormones,

micronutrients, organic sources, and inorganic salts, etc., are applied to

regulate hydration level and activate germinative metabolic activities without

radical protrusion (Hussain et al., 2015, 2018; Lutts et al., 2016; Zheng et al.,

2016). The abiotic cues prompt warning signals to enhance the plant defense