Treatment conditions and biochemical processes influencing seed priming effectiveness

Abstract

<p>A review of the scientific literature indicates osmotic priming (osmopriming) as the principal method of seed priming and polyethylene glycol (PEG) as the principal osmotic agent. An analysis of the available data across experiments carried out with different species under varying conditions showed an average 11% increase in percent germination and 36% shorter mean germination time (MGT) in primed vs. unprimed seeds. Moreover, in primed seeds MGT was less dependent on temperature, which is consistent with the effects expected from the treatment. Priming effects are mainly influenced by osmotic potential, temperature and time; major biochemical processes (repair of damaged DNA and RNA, preparation for cell division and increased antioxidant activity) are involved in treatment effects to an extent which is not fully ascertained in literature. A reduction of seed storage life is the major disadvantage of priming and the principal constraint to its diffusion, since dehydration to the initial moisture (drying-back) is needed to allow seed storage. Seed behaviour during drying-back, the role of the raffinose family oligosaccharides in cell membrane integrity and the expression of antioxidant enzymes in germinating seeds need to be further elucidated in a sufficient number of species, to promote a more reliable use of this technique.</p

Deciphering priming-induced improvement of rapeseed (Brassica napus L.) germination through an integrated transcriptomic and proteomic approach

“…In most plant species, seeds can remain desiccation tolerant prior to radicle protrusion; therefore, after soaking seeds can be subjected to a dehydration step permitting storage, distribution and planting of the primed seeds [7]. The accelerated germination and improved germination rate and uniformity has been attributed to seeds priming [8,9]. However, cellular and biochemical mechanisms of this phenomenon remain not well understood.…”

The effects of hydro- and osmopriming on the germination, vigour and hydrolytic enzymes activity of common zinnia (Zinnia elegans Jacq.) seeds

“…Properly conducted priming causes an increase in germination percentage and germination rate, enables seeds to germinate under a broader range of environmental conditions and improves seedling vigour and growth (McDonald 2000). The positive effects of priming are attributed to the induction of the biochemical mechanisms of cell repair, activation of the antioxidant defence system and induction of enzymes catalysing the decomposition and mobilisation of storage compounds (Di Girolamo and Barbanti 2012). Seeds generally contain starch, proteins and triacylglycerols, in proportions depending on the plant species, as sources of matter and energy.…”

“…Seeds generally contain starch, proteins and triacylglycerols, in proportions depending on the plant species, as sources of matter and energy. During germination, these three major nutrient reserves are hydrolysed specifically by amylases, proteases and lipases, respectively (Barros et al 2010, Di Girolamo andBarbanti 2012). α-Amylase hydrolyses starch into the simple sugar glucose (Kaneko et al 2002).…”

Seed priming improves irrigation water use efficiency, yield, and yield components of late-sown wheat under limited water conditions

“…Seed priming techniques are used to improve germination, to reduce the time between sowing and emergence, and for uniform emergence in the field, especially under adverse environments (Gupta et al 2008). The commonly used seed priming techniques are osmopriming (priming with osmotic solutions such as polyethylene glycol or inorganic salts), hydropriming (soaking in water), matripriming (hydrated solid materials), thermopriming (temperature treatment), hormonal priming, biopriming (coating of seeds with bioagents), and on-farm priming (reviewed by Girolamo and Barbanti 2012). Moreover, seed priming with solutions of antioxidants such as ascorbic acid, tocopherol, and glutathione is also useful in improving seed germination and seedling growth under adverse conditions (Draganic and Lekic 2012).…”