Check this out.. NASA did a experiment like this in May/2002: Sowing Seeds in a Magnetic Field

Ahhh I found a good forum full of info..
GM seeds vs. Magnetic GM seeds - The Environment Site Forums

"He then began experimenting on plants, and he found that when seeds were placed directly on a magnet (1500-2500 gauss strength) for several days, then planted, they had improved growth characteristics. In most cases South pole exposed seeds grew into stronger, more vigorous plants with better yields. North pole exposed seeds grew into smaller, weaker plants with lower yields. This was not always true, however. Depending on the species, some seeds responded best to the North pole, and sometimes both North and South pole exposed seeds were an improvement over unexposed seeds."