Seed vigor is the root of fast and uniform emergence and development of plants under variable environmental conditions. Biologists have investigated and developed several approaches to improve seed vigor and consequently plant establishment, including a seed invigoration technique known as seed priming. Seed priming is a pre-sowing treatment in which seeds are partially hydrated to a level that allows germination metabolic processes to initiate, sometimes accelerated by growth regulators, but seeds are held in the lag phase of germination thus preventing radical emergence. When primed seeds are sown, faster germination, greater synchronicity, improved seedling vigor and hence greater resistance to environmental stresses such as salinity and drought is often obtained. The most common forms of seed priming, based on the priming medium in which the seeds are soaked are hydropriming, halopriming, osmopriming and hormone priming. The implementation of these treatments may result in variable effects and harmful effects can result from inappropriate seed treatment. The desired effects of priming treatment are determined by several factors including plant species or variety, nature and concentration of priming medium, and length of soaking period. Variation in the efficacy of seed priming treatments between seed batches is a constraint to uptake of this technique. In order to facilitate a greater adoption of seed priming it will be necessary to develop more generic, safe priming protocols.
