Seed sprouting experiment with Arduino, toward better grow lights

I am designing a botany experiment, in seed germination. I wanted to measure the effect of light intensity and wavelength on seed sprouting (germination). It's becoming fairly well established that vegetation needs mostly only red and blue wavelengths at which chlorophyll A and B have absorption peaks. But not much is known about sprouting yet, what wavelengths it requires.

To make it interesting, I chose a "light dependent germinator." One which grows locally is Amaranth, which I bought at Native Seeds/SEARCH. The literature suggests germination may depend on wavelengths absorbed by Phytochrome.

My apparatus includes several parts:

1. Selection of LEDs, each tuned to one absorption peak of chlorophyl A (upper or lower), Chlorophyll B (upper or lower), Phytochrome. I reviewed a lot of literature on this and I am not quite confident that it's well-characterized yet. For instance, the absorption peaks vary depending on the spectroscopy method used. Using seeds of light-dependent germinators makes for small apparatus; this opens up the possiblity to use prisms or diffraction gratings to select from infinitely many arbitrary wavelengths.

2. Arduino clone (such as Teensy 2.0)

3. Solderless breadboard, mini


4. Moisture-resistance enclosure


5. Sterilization method (to inhibit mold growth). 3% hydrogen peroxide can be used to sterilize the container before starting.


6. Humidity control method (such as a saturated salt)


7. Temperature control method (because humidity is constant for saturated salt at a given temperature) or temperature buffer (such as a gallon jug of water next to apparatus inside a container indoors)


8. Watering system (this needs to keep the seeds moist enough, often enough, but not too wet too often)

I'll post photos and more information soon.

I am open to suggestions for the watering system, which can include a growth medium and should do so if the watering is not automated. I'm considering silica gel to retain water. A soda pop bottom upside-down will hold a vacuum and can dispense a trickle of water.