legallyflying
Well-Known Member
Hey there, it stands to reason that if your growing to grow weed then you have to know a little about plants. The following info is pretty basic stuff but its IMPORTANT. An understanding of how a plant functions will allow you to understand why you are observing certain problematic situations in the grow room and how you can fix them. A large part is cut and past from an Oregon State U website (my Alma mater) so some credit to them but its not all cut and paste.
Ok, so there are three main processes in plants and they are equally important. They are photosynthesis (duh), respiration, and transpiration. Here is the down low on these three processes:
[FONT=arial, helvetica, sanserif]Photosynthesis[/FONT]
One of the major differences between plants and animals is plants' ability to manufacture their own food. To produce food, a plant requires energy from the sun, carbon dioxide from the air, and water from the soil. During photosynthesis, it splits carbon dioxide into carbon and oxygen, adds water, and forms carbohydrates (starches and sugars). Oxygen is a by-product. The formula for photosynthesis can be written as follows:
Carbon dioxide + Water + Sunlight = Sugar + Oxygen
Photosynthesis doesn't cause your plant to grow, it creates energy stores that can be latter used for growth.. After producing carbohydrates, a plant either uses them as energy, stores them, or builds them into complex energy compounds such as oils and proteins. All of these food products are called photosynthates. The plant uses them when light is limited, or transports them to its roots or developing fruits. This is important as they also use them during times of stress.
Photosynthesis occurs only in the mesophyll layers of plant leaves and, in some instances, in mesophyll cells in the stem. Mesophyll cells are sandwiched between the leaf's upper and lower epidermis and contain numerous chloroplasts ( Figure 12), where photosynthesis takes place. Chloroplasts are incredibly small. One square millimeter, about the size of a period on a page, would contain 400,000 chloroplasts.
Chlorophyll, the pigment that makes leaves green, is found in the chloroplasts. It is responsible for trapping light energy from the sun. Often chloroplasts are arranged perpendicular to incoming sun rays so they can absorb maximum sunlight. If any of the ingredients for photosynthesis--light, water, and carbon dioxide--is lacking, photosynthesis stops.
The next process is respiration, which arguably is more important than photosynthesis as this is where the plant actually uses energy stores for growth... growth of buds my friend...buds!
Respiration
Carbohydrates made during photosynthesis are of value to a plant when they are converted to energy. This energy is used for cell growth and building new tissues. The chemical process by which sugars and starches are converted to energy is called oxidation and is similar to the burning of wood or coal to produce heat. Controlled oxidation in a living cell is called respiration and is shown by this equation:
C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy
This equation is essentially the opposite of photosynthesis. Photosynthesis is a building process, while respiration is a breaking-down process
Photosynthesis
Unlike photosynthesis, respiration does not depend on light, so it occurs at night as well as during the day. Respiration occurs in all life forms and in all cells. The process of respiration is a big reason why I don't personally believe in a 24hr light cycle. when the lights are on they are photosynthesizing and respiring, By giving the plants some "rest time" they can respire "uninhibited".
Lastly, there is Transpiration. You can think of transpiration more like "breathing and drinking" more than making and using food.
[FONT=arial, helvetica, sanserif]Transpiration[/FONT]
When a leaf's guard cells shrink, its stomata open, and water is lost. This process is called transpiration. In turn, more water is pulled through the plant from the roots. The rate of transpiration is directly related to whether stomata are open or closed. Stomata account for only 1 percent of a leaf's surface but 90 percent of the water transpired.
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. Transpiration is responsible for several things:
You have to remember that these process are just responses to the environment and simple physics. Transpiration is HUGE in your grow room and is (one of) the biggest reasons we control temperature and humidity.
Ok so those are the three major process but you might be thinking..soo how do my actions effect my plants. Its all about gradients and physics. A plant just responds to its environment. There are two main gradients to think about:
Moisture is attracted to drier environments
Water molecules move from a less saline to more saline environment.
If the air in your room is dry, water vapor will pass through the leaf and into the air. This is good, but if it is too dry, then the plants will be transpiring more water than they can move through the plant tissue and the plants will close their stomata and energy production ceases. If it is too humid, then water vapor does not pass out of the leaf and transpiration ceases. If transpiration ceases, then water and nutrients are not drawn up into the plant and obviously this is not a good thing as the plant can't deliver nutrients nor can it cool itself.
Salinity is probably the biggest thing. Your roots have a certain salinity or concentration of salts. Your growing medium and nutrients also have a salinity (ppm is a measure of salinity). If your roots are saltier than the surroundings, then water and nutrients are absorbed. The bigger the differential, the more the movement. If the medium becomes too saline from over fertilizing or not flushing the excess salts from your medium, then water does not pass into the roots. This is the mechanism behind over fertilization and is actually kind of funny. People try and give the maximum amount of nutrients to a plant but the more you give them, the less able they are to absorb them. This is the less is more mantra that you may hear from time to time on the forum. In people terms; eating a plate of spaghetti will give you energy. Eating 6 plates of spaghetti is not going to mean your going to be able to run a marathon.
Obviously this is an oversimplification of plant processes and is only meant to provide beginners with a baseline of information to start understanding the hows and whys of plant growth. Some amount of stress can be beneficial in the grow room. Plants typically grow more roots when exposed to drying conditions, the send out new shoots when injured, increase flowering hormones with decreasing light durations, and pack on resin glands to help ameliorate low humidity. I am still learning and evaluating all these different grow techniques just like most of us are. Hopefully this post will provide useful to some.
Learn > Grow > Prosper
Ok, so there are three main processes in plants and they are equally important. They are photosynthesis (duh), respiration, and transpiration. Here is the down low on these three processes:
[FONT=arial, helvetica, sanserif]Photosynthesis[/FONT]
One of the major differences between plants and animals is plants' ability to manufacture their own food. To produce food, a plant requires energy from the sun, carbon dioxide from the air, and water from the soil. During photosynthesis, it splits carbon dioxide into carbon and oxygen, adds water, and forms carbohydrates (starches and sugars). Oxygen is a by-product. The formula for photosynthesis can be written as follows:
Carbon dioxide + Water + Sunlight = Sugar + Oxygen
Photosynthesis doesn't cause your plant to grow, it creates energy stores that can be latter used for growth.. After producing carbohydrates, a plant either uses them as energy, stores them, or builds them into complex energy compounds such as oils and proteins. All of these food products are called photosynthates. The plant uses them when light is limited, or transports them to its roots or developing fruits. This is important as they also use them during times of stress.
Photosynthesis occurs only in the mesophyll layers of plant leaves and, in some instances, in mesophyll cells in the stem. Mesophyll cells are sandwiched between the leaf's upper and lower epidermis and contain numerous chloroplasts ( Figure 12), where photosynthesis takes place. Chloroplasts are incredibly small. One square millimeter, about the size of a period on a page, would contain 400,000 chloroplasts.
Chlorophyll, the pigment that makes leaves green, is found in the chloroplasts. It is responsible for trapping light energy from the sun. Often chloroplasts are arranged perpendicular to incoming sun rays so they can absorb maximum sunlight. If any of the ingredients for photosynthesis--light, water, and carbon dioxide--is lacking, photosynthesis stops.
The next process is respiration, which arguably is more important than photosynthesis as this is where the plant actually uses energy stores for growth... growth of buds my friend...buds!
Respiration
Carbohydrates made during photosynthesis are of value to a plant when they are converted to energy. This energy is used for cell growth and building new tissues. The chemical process by which sugars and starches are converted to energy is called oxidation and is similar to the burning of wood or coal to produce heat. Controlled oxidation in a living cell is called respiration and is shown by this equation:
C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy
This equation is essentially the opposite of photosynthesis. Photosynthesis is a building process, while respiration is a breaking-down process
Photosynthesis
- produces food
- stores energy
- uses water
- uses carbon dioxide
- releases oxygen
- occurs in sunlight
- uses food
- releases energy
- produces water
- produces carbon dioxide
- uses oxygen
- occurs in the dark as well as light
Unlike photosynthesis, respiration does not depend on light, so it occurs at night as well as during the day. Respiration occurs in all life forms and in all cells. The process of respiration is a big reason why I don't personally believe in a 24hr light cycle. when the lights are on they are photosynthesizing and respiring, By giving the plants some "rest time" they can respire "uninhibited".
Lastly, there is Transpiration. You can think of transpiration more like "breathing and drinking" more than making and using food.
[FONT=arial, helvetica, sanserif]Transpiration[/FONT]
When a leaf's guard cells shrink, its stomata open, and water is lost. This process is called transpiration. In turn, more water is pulled through the plant from the roots. The rate of transpiration is directly related to whether stomata are open or closed. Stomata account for only 1 percent of a leaf's surface but 90 percent of the water transpired.
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. Transpiration is responsible for several things:
- Transporting minerals from the soil throughout the plant.
- Cooling the plant through evaporation.
- Moving sugars and plant chemicals.
- Maintaining turgor pressure.
You have to remember that these process are just responses to the environment and simple physics. Transpiration is HUGE in your grow room and is (one of) the biggest reasons we control temperature and humidity.
Ok so those are the three major process but you might be thinking..soo how do my actions effect my plants. Its all about gradients and physics. A plant just responds to its environment. There are two main gradients to think about:
Moisture is attracted to drier environments
Water molecules move from a less saline to more saline environment.
If the air in your room is dry, water vapor will pass through the leaf and into the air. This is good, but if it is too dry, then the plants will be transpiring more water than they can move through the plant tissue and the plants will close their stomata and energy production ceases. If it is too humid, then water vapor does not pass out of the leaf and transpiration ceases. If transpiration ceases, then water and nutrients are not drawn up into the plant and obviously this is not a good thing as the plant can't deliver nutrients nor can it cool itself.
Salinity is probably the biggest thing. Your roots have a certain salinity or concentration of salts. Your growing medium and nutrients also have a salinity (ppm is a measure of salinity). If your roots are saltier than the surroundings, then water and nutrients are absorbed. The bigger the differential, the more the movement. If the medium becomes too saline from over fertilizing or not flushing the excess salts from your medium, then water does not pass into the roots. This is the mechanism behind over fertilization and is actually kind of funny. People try and give the maximum amount of nutrients to a plant but the more you give them, the less able they are to absorb them. This is the less is more mantra that you may hear from time to time on the forum. In people terms; eating a plate of spaghetti will give you energy. Eating 6 plates of spaghetti is not going to mean your going to be able to run a marathon.
Obviously this is an oversimplification of plant processes and is only meant to provide beginners with a baseline of information to start understanding the hows and whys of plant growth. Some amount of stress can be beneficial in the grow room. Plants typically grow more roots when exposed to drying conditions, the send out new shoots when injured, increase flowering hormones with decreasing light durations, and pack on resin glands to help ameliorate low humidity. I am still learning and evaluating all these different grow techniques just like most of us are. Hopefully this post will provide useful to some.
Learn > Grow > Prosper
