Experiment: Rate of Transpiration in 4 Conditions

[apple963]

I've done an experiment on rate of transpiration in 4 conditions.
1) ambient
2) ambient + fan
3) ambient + lamp
4) lamp + fan

result: the rates are
1) -0.367
2) -0.233
3) -0.197
4) -0.198

why the rate on condition 1 is the highest but not condition 4?

 

[Jack the Stri]

What is your experimental setup, what is the standard deviation on the results, ... You should maybe have taken a fan-only and a lamp-only condition into account as well. Did you perform a background measurement?

 

[apple963]

the set-up of expt:
select a stem with large leaves and insert into a tube under water without bubbles
the other end of the tube is connected to the pressure sensor of potometer
by data logging, the pressure change with time is observed under the 4 conditions. each condition allows 10min data logging.


condition 1: ambient (under ambient laboratory condition)
condition 2: ambient + fan ( position the leaf in a draught from a fan )
condition 3: ambient + lamp (position leaf under the halogen light)
condition 4: lamp + fan ( with both lamp and fan )