Strange craks in leafs

[vitomj]

Hi, anyone could help me to indentify why have some cracks on some leafs
Here are some pictures:

Any help is welcome
Thanks

 

[vitomj]

This new crack

 

[labexperiment]

What is your relative humidity?

 

[vitomj]

Hi, humidity is not yet controled because this is a experimental process.
But cracks in leafs are related to low moisture in the air?

I was spraying water to plant leafs frequently, can wet-dry repetitive cause this?

Thanks

 

[labexperiment]

That does sound reasonable, but I do not know the answer for sure.