I am writing a paper on the influence of sound waves on plant growth. I have read mechanical stimulation can open stomatas. What I was wondering was what is the amount of pressure the stomata needed to open or close. I take the high pressure of 5 MPa to mean the stomata is closed and the 0.3 MPa to mean the stomata is open? I'm trying to draw a correlation between air pressure and stomata opening. If you know of any research about this topic please let me know. I found a good number of resources, mostly coming from China. I have not been able to find much here in the states. There are papers coming from Canada but they were written about 40 years ago. I watched an episode of Myth-buster's where they performed the experiment and found some positive results.