|Lettuce seedlings at forty-two days of growth.|
I am still thinking of different ways to compare the seedlings as they grow. Here, I pulled the seedlings straight from a cell without being delicate at all. They are lined up from left to right by treatment: control, clear plastic, white plastic, plastic with holes, row cover, heat mat. Most of these little lettuces have wimpy little root systems.
Look at that last one on the right! It is nearly a plug! I suppose it seems obvious that using heat mats to keep the soil warm will stimulate root growth. The leafy part of this plug seems to be about the same size as three of the other treatments.
The biggest leaves come from the clear and white plastic treatments. Because of the non-porous nature of plastic water was retained in these two treatments making them pretty humid. My data collection notebook was often spattered with condensation falling from the ceiling of these tunnels. If I had any forethought I would have used my super cool waterproof notebook and a pencil to do all the data collection, but I didn't and have lots of crunchy, dried out pages of data to prove it.
|Mizuna seedlings at 42 days old.|
In contrast here are mizuna seedlings lined up in the same way: control, clear plastic, white plastic, plastic with holes, row cover, heat mat. They all have strong root systems and look pretty similar.