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

These alterations may result in membrane damage (Korkmaz et al., 2010),

oxidative stress (Shafi et al., 2009), reactive oxygen species (ROS) produc­

tion (Suzuki & Mittler, 2006), and reduced cellular respiration (Sugie et al.,

2006). Hydropriming is a simple, cost-effective, and promising method to

improve abiotic stress tolerance of plants by an increase in seed emergence

and synchronized germination (Jisha et al., 2013). This can be achieved

by stimulation of pre-germinative metabolic processes, metabolic repair,

osmotic adjustments, DNA processing, early reverse mobilization, energy

metabolism, and endosperm weakening (Chen & Arora, 2011; Pandita et al.,

2007; Varier et al., 2010). Moreover, germination is improved by regulating

DNA repair pathways, nucleic acid and protein synthesis, accumulation of

sterols and phospholipids, and enzyme degradation such as catalase, etc.

(Afzal et al., 2002; Paparella et al., 2015; Rajjou et al., 2012). Furthermore,

other factors like induced cell division, fluidity of plasma membrane, cell

elongation, and production of stress-responsive proteins play critical roles

in proper seedling development (Ibrahim, 2016). Priming procedures are

responsible for inducing stress defense mechanisms associated with abiotic

stresses such as increased antioxidant scavenging enzymes, accumulation

of HSP (heat shock protein), activation of membrane efflux, transcriptional

activation of peroxiredoxin, and LEA proteins (Catusse et al., 2011; Li et al.,

2005; Varier et al., 2010).

Hydro priming is a simple, safe, and economical technique used to

produce seedlings with increased capacity of osmotic adjustment thus

enhanced seed establishment and crop yield under environmental stress

(Kaur et al., 2002). The seeds are hydrated by immersing in distilled water

for a defined period determined by seed imbibitions at an appropriate

temperature. The seeds must be dried properly under shade to their original

weight (Jisha et al., 2013). However, germination is suspended due to low

osmotic and matric potential (Basra et al., 2003) but hydropriming induces

biochemical and physiological modifications in seeds before germination.

Modifications like increased permeability and lower viscosity of protoplast

attribute to increased nutrient and water uptake thus positive seedling growth

and resistance to dehydration (Jisha et al., 2013; Yagmur & Kaydan, 2008).

The predominant feature of hydropriming is the correlation between higher

water uptake and increased seedling growth (Yagmur & Kaydan, 2008).

This methodology is helpful under adverse environmental conditions as it

improves seed hydration and water uptake efficiency under these constraints

(McDonald, 2000). It is essential to maintain optimum temperature and

humidity to avoid uncontrolled water uptake and radicle protrusion (Taylor