ApexseasOG
Well-Known Member
In my quest to have the best possible grow space for my plants, I realized I had to study how ambient conditions affect plants in general. Turns out, as you would imagine, it all depends on the ambient conditions for your plants to either thrive or parish. From the amount of light it receives, the water it consumes, the nutrients it has available, the humidity in the air, amount of air being moved around the plant, etc, etc; everything plays a role. The focus of this study was initially about the appropriate air pressure that should exits inside a grow space but it turned out to be so much more. Here are my findings and my conclusions; please feel free to share your thoughts and personal experiences so that we may all benefit from the information and ultimately achieve better harvests.
First a quick breakdown on how plants work.
Using Co2, light, water, and nutrients from the medium, plants produce energy to grow; this process is called photosynthesis. Here’s how that works in a nut shell.
-Plants absorb Co2 through their stomata (consider the stomata a 2 way door in the surface of plants)
-Roots absorbs water, nutrients and minerals. These raw materials flow to the plant cells containing chlorophyll
-The chlorophyll in the plants uses the light it absorbs along with the Co2 to produce “food” to grow.
In the process, it uses the carbon and releases the oxygen in the Co2 molecule it absorbed. After all we are all carbon based life forms and plants are not the exception. The plant uses the carbon to build itself and releases oxygen for us to breath as a by-product of that process.
The process in which plants use the “food” made by photosynthesis which produces energy which releases water (through transpiration) and carbon dioxide is called respiration. Both cellular respiration and photosynthesis are parts of a mutually beneficial relationship. Photosynthesis cannot occur without cellular respiration and cellular respiration certainly cannot occur without the photosynthesis.
The other important process is transpiration. It’s basically the movement of water through the plant. Water is absorbed through the root hairs, is transported through the plant due to osmosis, and exits through the stomata (remember that 2-way door that also takes in Co2) and evaporates. Transpiration is important because water is needed for photosynthesis, it carries nutrients from the roots to the cells and because water cools the plant off. Transpiration is a necessary process and uses about 90 percent of the water that enters a plant's roots. The other 10 percent is used in chemical reactions and in plant tissues. The amount and rate of water loss depends on factors such as temperature, humidity, and wind or air movement. Transpiration often is greatest in hot, dry (low relative humidity), windy weather.
Now that we have a basic understanding of how plants work we can better understand the conditions that are needed for optimal growth and health.
In order for a plant to grow and develop properly, it must balance photosynthesis, respiration, and transpiration. Left to their own devices, plants do a good job of managing this intricate balance. For example:
VPD Calculator
Taking all this to account I have formulated what to me would be the best conditions for an enclosed grow space that can control its temperature, humidity, air pressure, Co2 levels, and ventilation.
Seed and seedling stage:
high humidity (80%-85%)
temperature from 80f - 85f
low air pressure
no added CO2
low inside ventilation
Vegetative stage:
normal humidity (60%-70%)
temperature from 70f - 85f
normal air pressure
low added CO2 pressure
normal inside ventilation
Flower stage:
low-normal humidity (40%-60%) (the lower the humidity the higher rates of photosynthesis at these levels of air and Co2 pressure)
temperature from 70f to 80f
high air pressure
high added CO2 pressure
high inside ventilation
If anyone has any experiences, input, ideas, comments or whatever you would like to share please do so. I hope this helps in some way anyone looking to understand more how plants work and how we can better provide them with the conditions they need to thrive.
How I plane to achieve all this in a custom 36''w x 20''d x 50''h will be for another thread which is in the making. Stay tuned for that one.
These are the studies referenced in this thread:
Plant Responses to Reduced Air Pressure: Advanced Techniques and Results
Gas Exchange and Growth of Plants Under Reduced Air Pressure
Effects of Elevated Pressure on Rate of Photosynthesis During Plant Growth
High pressure effect on photosynthetic properties of green plant leaves
First a quick breakdown on how plants work.
Using Co2, light, water, and nutrients from the medium, plants produce energy to grow; this process is called photosynthesis. Here’s how that works in a nut shell.
-Plants absorb Co2 through their stomata (consider the stomata a 2 way door in the surface of plants)
-Roots absorbs water, nutrients and minerals. These raw materials flow to the plant cells containing chlorophyll
-The chlorophyll in the plants uses the light it absorbs along with the Co2 to produce “food” to grow.
In the process, it uses the carbon and releases the oxygen in the Co2 molecule it absorbed. After all we are all carbon based life forms and plants are not the exception. The plant uses the carbon to build itself and releases oxygen for us to breath as a by-product of that process.
The process in which plants use the “food” made by photosynthesis which produces energy which releases water (through transpiration) and carbon dioxide is called respiration. Both cellular respiration and photosynthesis are parts of a mutually beneficial relationship. Photosynthesis cannot occur without cellular respiration and cellular respiration certainly cannot occur without the photosynthesis.
The other important process is transpiration. It’s basically the movement of water through the plant. Water is absorbed through the root hairs, is transported through the plant due to osmosis, and exits through the stomata (remember that 2-way door that also takes in Co2) and evaporates. Transpiration is important because water is needed for photosynthesis, it carries nutrients from the roots to the cells and because water cools the plant off. Transpiration is a necessary process and uses about 90 percent of the water that enters a plant's roots. The other 10 percent is used in chemical reactions and in plant tissues. The amount and rate of water loss depends on factors such as temperature, humidity, and wind or air movement. Transpiration often is greatest in hot, dry (low relative humidity), windy weather.
Now that we have a basic understanding of how plants work we can better understand the conditions that are needed for optimal growth and health.
In order for a plant to grow and develop properly, it must balance photosynthesis, respiration, and transpiration. Left to their own devices, plants do a good job of managing this intricate balance. For example:
- If a plant photosynthesizes at a high rate, but its respiration rate is not high enough to break down the photosynthates produced, photosynthesis will either slow down or stop.
- If respiration is much more rapid than photosynthesis, the plant won't have adequate photosynthates to produce energy for growth. Hence, growth either will slow down or stop altogether.
- When stomata are open, transpiration occurs, sometimes at a very high rate. Plants have problems if they loose too much water, so stomata close during hot, dry periods when transpiration is highest. However, CO2, which is needed for photosynthesis, also enters the plant through open stomata. Thus, if stomata stay closed a long time to stop water loss, not enough CO2 will enter for photosynthesis. As a result, photosynthesis and respiration will slow down, in turn reducing plant growth.
- According to studies, rates of respiration decrease with increased pressure and high humidity but increase with higher pressure and low humidity.
- Other studies also say that the rate of net photosynthesis would increase 1.6-fold with increased total pressure and partial pressure of Co2 at relatively low humidity.
- Studies also show that at very low pressures, transpiration is enhanced significantly but growth is slowed due to factors such as the plant going into dehydration mode because it has transpired more water than it holds and the lack of enough oxygen molecules in the air.
- Air pressure can also even affect the spectrum to which the chlorophyll in the plants reacts to. In one study high pressure systems shifted the spectrum at a rate of 0.083 nm/bar. Meaning that for every bar of pressure raised the spectrum shifted 0.083 nanometers. (This is much more complicated though and I haven’t quite gotten my head around it entirely as research on this is still thin.)
VPD Calculator
Taking all this to account I have formulated what to me would be the best conditions for an enclosed grow space that can control its temperature, humidity, air pressure, Co2 levels, and ventilation.
Seed and seedling stage:
high humidity (80%-85%)
temperature from 80f - 85f
low air pressure
no added CO2
low inside ventilation
Vegetative stage:
normal humidity (60%-70%)
temperature from 70f - 85f
normal air pressure
low added CO2 pressure
normal inside ventilation
Flower stage:
low-normal humidity (40%-60%) (the lower the humidity the higher rates of photosynthesis at these levels of air and Co2 pressure)
temperature from 70f to 80f
high air pressure
high added CO2 pressure
high inside ventilation
If anyone has any experiences, input, ideas, comments or whatever you would like to share please do so. I hope this helps in some way anyone looking to understand more how plants work and how we can better provide them with the conditions they need to thrive.
How I plane to achieve all this in a custom 36''w x 20''d x 50''h will be for another thread which is in the making. Stay tuned for that one.
These are the studies referenced in this thread:
Plant Responses to Reduced Air Pressure: Advanced Techniques and Results
Gas Exchange and Growth of Plants Under Reduced Air Pressure
Effects of Elevated Pressure on Rate of Photosynthesis During Plant Growth
High pressure effect on photosynthetic properties of green plant leaves
