Abstract
Abiotic stresses such as drought, extreme temperature, and salinity can negatively impact seed germination and plant growth and have become major limitations to crop production. Most crops are vulnerable to abiotic stress factors during their early growth phase, especially during seed germination and seedling emergence. Rapid crop seed germination and seedling establishment is known to provide competitive advantages over weeds and improve yields. Seed osmopriming is defined as a pre-sowing treatment in which seeds are soaked in osmotic solutions to undergo the first stage of germination, but radicle protrusion has not occurred. The process of osmopriming involves prior exposure of seeds in low-water-potential solutions. Osmopriming can generate a series of pre-germination metabolic activities, increase the antioxidant system activities, and prepare the seed for radicle protrusion. Polyethylene glycol (PEG) is a popular osmopriming agent that can alleviate the negative impacts of abiotic stresses. This review summarizes research findings on crop responses to seed priming with PEG under abiotic stresses. The challenges, limitations, and opportunities of using PEG for crop seed priming are discussed with the goal of providing insights into future research towards effective application of seed priming in crop production.
Highlights
Abiotic stresses are a common cause of crop yield reduction worldwide
Plants may suffer greater detrimental effects when they are exposed to multiple abiotic stresses, such as cold and drought, heat, and heavy metal, as well as drought and heat, than when they are exposed to each individual stress [7,8,9,10]
The effectiveness of Polyethylene glycol (PEG) priming against different abiotic stresses has been shown in a wide range of crop species
Summary
Abiotic stresses are a common cause of crop yield reduction worldwide. Yield loss may occur when crops suffer from various abiotic stresses such as cold, heat, drought, freezing, flooding, heavy metals, UV-light, and mineral deficiency [1,2,3,4,5,6]. PEG-primed plants exhibit positive effects on seed germination, seedling establishment, and yield, but the benefit is variable depending on several factors such as crop species and stress type [47,48,49,50]. PEG priming caused a rapid enhancement of some antioxidant enzymes in seedlings exposed to drought stress, mitigating the detrimental effect on seed germination and stand establishment [5,58,67]. Zhang et al [5] found that unprimed sorghum seedlings demonstrated increased electrolyte leakage and O2− content, and decreased membrane stability under drought conditions; PEG-primed sorghum seedlings exhibited less lipid peroxidation, improved cell membrane stability, and enhanced activities of APX, CAT, POD, and SOD. Previous evidences collectively indicate that enhanced drought tolerance in PEG-primed plants is likely due to elevated antioxidant activities that restricted the accumulation of ROS [5,9,53,65,66,67]
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