Cover the planted containers until the seeds have germinated. Place 3 of the containers where they will receive light from directly above. Place the other 3 where the strongest source of light will be from the side of the containers. If possible, block any additional light source. One way of doing this would be to place the seedlings in a box on its side, with a lamp at the opening.
Record changes over a period of time.
Corn seed, potting soil, containers and a lamp that can direct the light. Marigold seedlings will not show a difference if fed with different brands of the same formula fertilizer. After they have gotten their first true leaves, start fertilizing 4 of the containers with the Miracle Gro according to directions. Fertilize 4 more with Bachman's brand and just give water to the last four. Keep the three groups separate so excess water from one group cannot be absorbed by another.