Seed priming is a method which consists in submerging the seeds in water.The optimal soaking time is about 8 hours for millet, sorghum and cowpea, while maize needs about 15 hours (Harris 2006). Then the seeds are surface dried and sowed immediatly. The priming of seeds may take place after some significant rain. The priming has multiple effects on plant development such as (Harris 2006):

• Germination time is reduced from 3 days to 1
• Plant collection is more uniform
• Plant vigour is higher
• The time between planting and harvesting is reduced
• Plants are  more resistant to insect and fungus attacks
• There is higher output

Seed priming is effective for crops such as pearl millet, sorghum, maize, cowpea, wheat, chickpea, cotton, and rainfed rice. The method is particularly interesting in marginal environments such as the Sahel. As far as wheat is concerned, there is no effect of priming if the yield is higher than 2 tons per hectare. In marginal conditions, replanting is often required. The priming method reduces the necessity to replant. One of the effects of priming seems to be that plants are more resistant to higher temperatures after planting. For pearl millet, it has also been shown that plant establishment is better, particularly where the soil is not humid. The rapid development of plants after planting also increases the accumulation of plant nutrients such as nitrogen in the plants (Harris 2006). 

If the grains are dried on the surface, it is also possible to mix the seeds with fertilizer. This is a method used in India.   

It is possible to dry the seeds back to the humidity they had before the seed priming started, but the effect on yield will be less significant if such seeds are sown. It is possible to store dried seeds for a few days. 

Seed priming also reduces mildew attacks on pearl millet (Harris 2006).

Seed priming is a method that is already adopted in India, particularly for chickpea and rainfed rice. DCG is testing the priming method in Mali and Ethiopia and the preliminary results are promising.

On-farm tests by DCG in in 2007 have shown the synergetic effect of seed priming and microdose of fertiliser (see the next chapter). This method leads to a noticeable increase in crop yields of about 92% for millet and 138% for sorghum in comparison to the absolute reference/control farms (with neither seed priming nor use of fertilisers). On the other hand, seed priming alone stimulates seed germination and improves the crop yields by about 48% for millet and 52% for sorghum compared to the absolute reference/control farms (with neither seed priming nor use of fertilisers). Beside these effects, the use of the seed priming technique in combination with the microdose of fertilisers increases crop yields by about 60% and 30% for sorghum and millet respectively as compared to the use of seed priming alone.

Figure: Effect of seed priming on sorghum yields in Konobougou 2006, Mali

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