Nature

Interesting, but I don't think that really answers the question because only a portion of the tree is directly responsible for the process, which is called Non-Cyclic Photophosphorylation. It also involves sugar.

If the tree is dormant, as it is in winter, then the production of oxygen is virtually nil. On the other hand, in summer it is most robust. Only the green portion of the tree actually undergoes photosynthesis, which is the engine that creates the byproduct O2.

A photon will knock an electron into a higher excited state, where the electron is ultimately accepted by another molecule to become a negative ion. This is where the water comes in and the equation cited by PWSlack. The sugar is used to fuel the respiration process which liberates the O2.

The trick is going to be to figure out how much photosynthesis actually takes place. The amount of light striking the tree and the amount of chlorophyll in the tree, and the amount of water available to the tree are key factors.

It is relatively simple to understand the process, but much more difficult to predict the production output due to the large number of conditions and their possible status. Not everything is equal. The shape of the tree and any neighbors that shade the tree impact the production as do water content sunlight availability, etc. So the mass of the tree, roots and all, isn't a good measure of O2 output. For that matter, the roots and trunk do not directly play at all with photosynthesis, they are only the supporting network for the tree. Sort of like a highway supports the trucking industry.

thank u sir for ur reply, but i do not want that much ,my doubt is we all know that tree liberates oxgen and takes carbondioxide.The main reason for asking this question is, i want to teach the children the importance of tree for human beings whereas we are cutting down the trees beside roads in the name of traffic.

Thank you very much sir

You might try asking at a local science museum. Explain what you are trying to do and they may have some data or at least be able to point you in the right direction.

Good luck and it sounds like a wonderful idea.

thank u sir for ur reply, but i do not want that much ,my doubt is we all know that tree liberates oxgen and takes carbondioxide.The main reason for asking this question is, i want to teach the children the importance of tree for human beings whereas we are cutting down the trees beside roads in the name of traffic.

Thank you very much sir

Prior to this I had never heard of a neem tree. I have now.