Seed Priming: A way towards improving seed quality

By Talha Javed, Rubab Shabbir and Ahmed Mukhtar, University of Agriculture, Faisalabad, Pakistan

Seed priming is a seed treatment that modulate the germination process by handling the temperature and seed moisture content. The seed is taken through a biochemical process within that activates the early stages of germination.

The priming procedure regulates the seed’s temperature and moisture content, bringing the seed closer to the point of germination and then carefully dried to stop germination for planting. When the primed seeds are planted, you are shortening the germination time and improving the uniformity of the crop upon emergence.

Priming Objectives

• To decreases the time to germination.
• To increase the rate of germination.
• To improve emergence from the soil faster and uniformly.
• To eradicate or greatly reduce the amount of seed-borne fungi.

Seed Priming Process

Seed priming and agriculture

Pre-sowing priming induces a physiological status in seeds and has emerged as a promising strategy to improve plant behavior in the field. There is a strong interest for farmers and seed companies to find suitable cheap priming treatments but also to precisely identify the agronomical properties improved as a result of priming in cultivated species.

Priming methods and priming agents

Several methods of seed priming have been developed in order to stimulate seeds and lessen the environmental stresses. A common feature of water-based priming techniques, which distinguishes them from other pre-sowing treatments, is partial seed pre-hydration and the activation of early germination events in seed.

Hydropriming

Hydropriming is the easiest method of seed priming, which relies on seed soaking in clean water and re-drying to original moisture content prior to sowing.

Osmopriming

Osmopriming involves soaking seeds in osmotic solution with low water potential instead of pure water. Low water potential of osmotic solutions, water enters seed gradually which allows gradual seed imbibition and activation of early phases of germination but prevents radicle protrusion.

Solid matrix priming

Solid matrix priming (SMP) in which water uptake by seeds is controlled, has been developed as a substitute method to osmo-priming because of high cost of osmotic agents and technical problems with aeration.

Hormopriming

During hormopriming, seeds imbibition occurs in the presence of plant growth regulators, which can have direct impact on seed metabolism. Hormones which are commonly used are abscisic acid, auxins, gibberellins, kinetin, ethylene, polyamines, and salicylic acid (SA). Gibberellic acid (GA3) and PEG priming.

Biopriming

Biopriming involves seed imbibition together with bacterial inoculation of seed.

On-farm seed priming

Farmers can prime their own seed if they know the safe limits. The safe limits are calculated for each variety so that germination will not continue once seeds are removed from the water. A primed seed will only germinate if it takes up additional moisture from the soil after sowing.

It is important to note this distinction between priming and pre-germination-sowing pre-germinated seed under dryland conditions can be disastrous. In most cases seed can be primed overnight and is simply surface-dried and sown the same day.

Apart from swelling slightly and weighing more, primed seed can be treated in the same way as non-primed seed. Occasionally, sowing may be unavoidably delayed by heavy rain, for example. If primed seed is surface-dried and kept dry it can be stored for several days, then sown as usual and still perform better than non-primed seed.

Advantages

• Enhances the germination percentage
• Enhances the speed and uniformity of germination
• Improves the resistance towards water and temperature stress
• Increases the shelf life of seed
• Highly suitable for small seeds
• Enhances the yield

Conclusion

Seed priming is an old empirical strategy used by farmers, and by seed companies, to improve germination processes in cultivated plant species. The underlying mechanisms involved in this positive impact of pre-sowing treatments remained unclear for a long time. However, seed priming is a good adaptive approach in mitigating the seed quality related problems. The present review aimed to summarize recent information provided by various tools helping in seed priming.