Re: If you were to plant two batches of seeds and grow one batch in the ...

The short answer to your question is that it depends on the plant. For bean seeds it might not make much difference, but for other seeds this is not the case.

Light is very important to plants and controls many of their developmental processes. It is to the plant's advantage to germinate at a time and place where it has a good chance of being successful since it cannot pick up and move if conditions are less than optimal. For some plants, light is a trigger mechanism for germination. Many introductory labs do the lettuce seed germination experiment showing the requirement fot red light for germination. But for many other plants, all that is required is moisture and warm temperature.

A general reason for this is that small seeds (such as lettuce) must be near the surface to be successful and their way of determining that they are near the surface is if they detect light (red light can get into loosly packed soil for about 2 cm). Small seeds with small food reserves are wasting their germination if the are too deep and can never get to the surface. Large seeds with large food reserves do not need to be so close to the surface. In fact light may inhibit some, indicating to them that they are too close to the surface and there may not be enough soil. In addition some plants are fine-tuned to germinate only at a certain time of the year, and phytochrome (the red light detecting pigment) can be used to determine day length.

In terms of doing the experiment, just planting the seeds in the light might be enough to trigger or inhibit germination even if they are then placed in the dark. The germination process has already begun. Keeping all this in mind, try the experiment with several different seeds and let me know how it comes out.

For a review of factors affecting seed germination, go to: http://koning.ecsu.ctstateu.edu/Plants_human/seedgerm.html

To read about some recent research, go to: http://urelations.ucdavis.edu/PubComm/newsreleases/09.97/news_phytochrome.html