Samwell Seed Well
Well-Known Member
im plucking this from another user on another site EfuckingC thanks
"All,
Vapor Pressure is the plants sensing of RH. Water pressure inside a cell is what keeps it turgid. The leaf senses water pressure outside as well. The difference in vapor pressure inside and outside of the cell/leaf is what signals stomata to open or close. Stomata control transpiration co2 fixation et al. Essentially, they control growth rate. Warmer temps combined with low RH drive Vapor Pressure down. Humans call this measurement torrs.....24 torrs is known as the "mendoza line".....above it is a positive VP and below is Vapor Pressure Deficit. A high deficit, (NOT a high vapor pressure....two different things.....high VP is good.....high deficit is not....keep clear)
means the atmosphere has insufficient h20 to balance the water lost by leaves in transpiration so it must suck large amounts up from the roots. when this happens the plant is working harder than usual at maintaining internal water pressure and this causes stress, and stomata close.....an "immune system response" if you will, to lessen stress. When this happens nute uptake is reduced, cooling function of the leaf is reduced and growth slows and your yield slows. Thats icky.
So, how do we stay above the mendoza line?
I cannot get my chart into digi format.....frankly, I dont follow things just because they are "in a grow book". The book that Dem and i have suggests even higher RH than i am willing to go. For 80f chart suggests RH of 80%. I dont doubt that this would be ok for plant and this is max stomata opening numbers but in a fruiting plant that is susceptable to rot , fuck that.....experience says that i have no issues at 65 with occasional peaks at 70. I use well aerated soil, flush properly and lots of compost tea means healthy roots and rot is not an issue. There is a noticeable difference in my yield at 65 vs 45 RH.
Do a little research for yourself and go from there. Creeping up each cycle is a great way to try it and aleviate concerns of f-ing up. Just dont expect big differences in yield with 5% changes in RH. IMO, below 50% is a mistake and hurting you."
any of you have any thoughts of this, my humidity is normally a little high . .. . how about you
heres a link to an article
http://urbangardenmagazine.com/2010/07/plantworks-part-1-humidity-and-vapor-pressure-deficit/
"All,
Vapor Pressure is the plants sensing of RH. Water pressure inside a cell is what keeps it turgid. The leaf senses water pressure outside as well. The difference in vapor pressure inside and outside of the cell/leaf is what signals stomata to open or close. Stomata control transpiration co2 fixation et al. Essentially, they control growth rate. Warmer temps combined with low RH drive Vapor Pressure down. Humans call this measurement torrs.....24 torrs is known as the "mendoza line".....above it is a positive VP and below is Vapor Pressure Deficit. A high deficit, (NOT a high vapor pressure....two different things.....high VP is good.....high deficit is not....keep clear)
means the atmosphere has insufficient h20 to balance the water lost by leaves in transpiration so it must suck large amounts up from the roots. when this happens the plant is working harder than usual at maintaining internal water pressure and this causes stress, and stomata close.....an "immune system response" if you will, to lessen stress. When this happens nute uptake is reduced, cooling function of the leaf is reduced and growth slows and your yield slows. Thats icky.
So, how do we stay above the mendoza line?
I cannot get my chart into digi format.....frankly, I dont follow things just because they are "in a grow book". The book that Dem and i have suggests even higher RH than i am willing to go. For 80f chart suggests RH of 80%. I dont doubt that this would be ok for plant and this is max stomata opening numbers but in a fruiting plant that is susceptable to rot , fuck that.....experience says that i have no issues at 65 with occasional peaks at 70. I use well aerated soil, flush properly and lots of compost tea means healthy roots and rot is not an issue. There is a noticeable difference in my yield at 65 vs 45 RH.
Do a little research for yourself and go from there. Creeping up each cycle is a great way to try it and aleviate concerns of f-ing up. Just dont expect big differences in yield with 5% changes in RH. IMO, below 50% is a mistake and hurting you."
any of you have any thoughts of this, my humidity is normally a little high . .. . how about you
heres a link to an article
http://urbangardenmagazine.com/2010/07/plantworks-part-1-humidity-and-vapor-pressure-deficit/
