I took a break from the skids today because I ran out of screws. So I worked on the growth chamber for the next tomato experiment. I’m not sure how much of this is of interest or useful, but I installed 50 LED tubes on the top, separated from the plant area with a diffuse greenhouse plastic sheet. I then put reflective mylar on top so any stray lamp light is reflected down towards the plants. I wired up about 70% of the lamp tubes and made a design for the rest of the wiring. Tomorrow I will go to town for all the parts (and screws).
I mounted load cells on the ends, there will be two hydroponic slabs with one tomato plant each at either end of the chamber. I will also have the runoff irrigation drip into a bucket that is on a load cell so I can measure the transpiration very precisely. I also started wiring up the stepper motors that will control the light sensor gantry below the plants, but I didn’t get it moving yet.
Probably this experiment will turn into a preprint paper of “Measuring light absorption of tomato plants trained horizontally” and I’ll give an estimate for the light absorption per m2 of floor area, plus all the details of how to build a growth chamber like this one. There are no experiments out there since most people don’t care about growing tomatoes horizontally.
The only reason I care is that there are two possible routes to winter tomatoes that I can see. First is the conventional heated greenhouse with electric lights to cover low-light days in the winter. The other is to build a larger greenhouse where the tomatoes can grow horizontally to absorb enough natural light even on low-light days. The question is: what is more cost-effective? That’s what I have to figure out by testing the horizontal version.
Sun Aquasystems 