Photosynthesis and Respiration and O2/CO2 levels

bridgetown1

I have 25+/- pea seedlings, each about 12cm tall, in an enclosed and airtight transparent container.I have a light shining on them. I have CO2 gas and O2 gas asensors inserted into the container.

But my O2 levels are dropping steadily and CO2 levels rocketing.

How many seedlings and of what age would let me clearly show the idea of 'compensation point'? Am I right in saying that the Eden Project in Cornwall had similar problems???

Capt'n Midnight

just asking stupid questions

are the plants warm enough to grow ?

is there anything in the soil decaying ?

Biosphere 2 had problems with CO2 but that was due to the concrete.

steddyeddy

bridgetown1 wrote: »

I have 25+/- pea seedlings, each about 12cm tall, in an enclosed and airtight transparent container.I have a light shining on them. I have CO2 gas and O2 gas asensors inserted into the container.

But my O2 levels are dropping steadily and CO2 levels rocketing.

How many seedlings and of what age would let me clearly show the idea of 'compensation point'? Am I right in saying that the Eden Project in Cornwall had similar problems???

It sounds like the humidty is affecting the amount of CO2 the plant's stomata are taking in.

phragmities

If they are growing in soil the microbes in the soil may be respiring too. Also artificial light is of a much lower intensity than sunlight, at most 10% and there are also light quality affects, not all visible light is usable by the plant for photosynthesis. The quality of your lighting ie the amount of PAR (photosynthetically active radiation) may have an affect on the plants ability to carry out photosynthesis. Do the seedlings have normal growth and appearance? Do they look etiolated? Yellowish with leggy stems and small leaves?
If they are not getting enough light of the right quality they will continue to use the store of carbohydrate in the cotyledons as an energy source and be unable to use up the resulting CO2.

Squeaky the Squirrel

http://www.dailymail.co.uk/sciencetech/article-2267504/The-sealed-bottle-garden-thriving-40-years-fresh-air-water.html