How much light energy is lost when putting a plant's leaf or leaves into a sealed plastic bag?

Question

We want to prove to our professor plants with an abundance of CO2 will grow better than those in nominal levels of CO2. We hypothesize putting a thin tube from a CO2 tank into a semi-sealed bag with a plants leaf(s) will effectively increase the CO2 ppm to grow our plants bigger than just by using "normal" ppm air. Our goal is to sparingly use CO2, as opposed to pumping CO2 into the entire plant environment. In essence, we're making a specialized plant controlled envionment for leaves alone.

Answer 1

The light energy lost is insgnificant

Answer 2

if you do the experiment with a control-leaves covered with an equivalent plastic bag but with hole(s) large enough to allow 'adequate' air circulation-without changing other factors---then you can be reasonably certain that the CO2 is the factor that results in any differences that might result