Dear members,
How to arrange the tree way treatment arrangement under control Chamber?
If you aren't bothered about a control you will need four chambers: A) No treatment and half the plants with normal watering conditions and half with the drought conditions, B) CO2 and 50/50 normal/drought, C) Heat conditions and 50/50 normal/drought and D) CO2+Heat and 50/50 normal/drought
If you are concerned with a control you will need eight chambers: Same as above but two chambers of each.
The thing is that you might have a chamber effect. Let's say that you have two chambers: Chamber A is located on the corner of the building with many trees shading the chamber from the outside, while Chamber B is located further to the side with no trees shading the chamber from the outside. The presence of trees on the outside might (possibly) have an effect on what you measure inside the chambers. You can also imagine that chamber A doesn't work very well but chamber B works perfectly. It is therefore good research practice to have two different chambers with the same treatment to see if there is a difference between these two chambers, this is called chamber control.
Therefore if you can afford this it is optimal with your set-up to have eight chambers A - H: A) No treatment and half the plants with normal watering conditions and half with the drought conditions, B) CO2 and 50/50 normal/drought, C) Heat conditions and 50/50 normal/drought and D) CO2+Heat and 50/50 normal/drought. E) No treatment and half the plants with normal watering conditions and half with the drought conditions, F) CO2 and 50/50 normal/drought, G) Heat conditions and 50/50 normal/drought and H) CO2+Heat and 50/50 normal/drought.
By doing this you can see if you get the same result in chamber A and E, same in chamber B and F, same in chamber C and G and same in chamber D and H.
However, if you can only afford four chambers then doing
A) No treatment and half the plants with normal watering conditions and half with the drought conditions, B) CO2 and 50/50 normal/drought, C) Heat conditions and 50/50 normal/drought and D) CO2+Heat and 50/50 normal/drought
will be okay, since chamber A is the control (with no extra CO2 or Heat).
Dear Carl Alexander Frisk ,
Thank you very much again for your unreserved help !
Best Regards,