Priming Seed

Seed Priming - Risks and Rewards |
Building a Pre-Fabricated House The basic framework of a pre-fabricated house is built inside a factory. The walls and roofing are built in an environment that is ideal for the workers, and building efficiencies are best. However, the house is not completed inside the factory. The pre-built walls and roofing are taken to the building site where the house iscompleted. Building a house at a building site where the walls and roofing are already completed takes less building time at the site, and therefore houses go up faster and more efficiently.Seed Priming is like building a pre-fabricated house.What’s Seed Priming?Seed Priming starts the germination process in the lab or plant, like a pre-fabricated house is started in the factory. The basic chemicalreactions or framework needed for the seed to germinate occurs in the lab or plant under high moisture and ideal temperature conditions. Seed moistures are set at a level just below what’s needed for actual germination, but just enough to get the process going. Once the framework for actual germination is built, you can dry the seed down to stable moisture levels and plant the seed at the fieldsite where the rest of the germination process can take place, when the seed comes in contact with soil moisture. Like the pre-fabricated house, seed germination in the field takes less time, because part of the germination process in already complete.Why Prime Seed?Primed seed usually emerges from the soil faster, and more uniformly than non primed seed of the same seed lot. These differences aregreatest under adverse environmental conditions in the field, such as cold or hot soils. There may be little or no differences between primed and non primed seed if the field conditions are closer to ideal. Some growers use seed priming during the earlier plantings in cold soil, and not later in the season when conditions are warmer. Lettuce growers in the Southwest region of the United States useprimed seed in the hottest part of the season, when lettuce may not be able to germinate due to the extreme heat. These growers switch back to non primed seed during the cooler season.Seed Priming RisksThe number one risk when using primed seed is reduced seed shelf life. Depending on the species, seed lot vigor, and the temperature and humidity that the seed is being stored, a primed seed shouldremain viable for up to a year. If you store primed seed in hot humid conditions, it will lose viability much more quickly. In most all cases however, primed seed has shorter shelf life than the non primed seed of the same seed lot. For this reason, it’s best not to carry primed seed over to the next growing season. |
Seed priming and pregerminated seedSeed priming is the most importantphysiological seed enhancement method. Seed priming is an hydration treatment that allows controlled imbibition and induction of the pregerminative metabolism ("activation"), but radicle emergence is prevented. The hydration treatment is stopped before dessication tolerance is lost. An important problem is to stop the priming process in the right moment, this time depends on the species and the seedbatch. Molecular marker can be used to control the priming process. Priming solutions can be supplemented with plant hormones or beneficial microorganisms. The seeds can be dried back for storage, distribution and planting. Germination speed and synchronity of primed seeds are enhanced (see figures below) and can be interpreted in the way that priming increases seed vigor (short or no "activation"time). A wider temperature range for germination, release of dormancy and faster emergence of uniform seedlings is achieved. This leads to better crop stands and higher yields. A practical drawback of primed seeds is often a decrease in storability and the need for cool storage temperatures.

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Several types of seed priming are commonly used:
Osmopriming...