Basic Plant Physiology |
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| If you know how your plants are structured and how they react and grow, you can tailor your growing methods to maximize your growth and yield. Make the most of your plant's natural potential by learning all about the nuts and bolts of plant growth. |
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Basic Plant Physiology.
How a plant functions. Below are the three main plant functions: photosynthesis, transpiration and nutrient uptake and transport. These three components combine to produce food and energy and make your plant grow. They are common to every variety of plant you could ever wish to grow hydroponically and are the key factors that you need to consider whilst cultivating indoor plants. Bear in mind that plants are about 80% water. There is water in and around all plant cells which can travel throughout your plant by osmosis or diffusion. This water movement is crucial to your plants development as it can provide water to every part plant which is essential for photosynthesis as well as carrying dissolved nutrients and minerals around the plant.
Photosynthesis.
The leaves are the engines of the plant. They are adapted to bring together the raw materials, water, carbon dioxide and light to produce energy for the plant in the form of sugars (glucose) through photosynthesis. These sugars will then be transported from the leaves to use elsewhere in the plant.
The leaf does this in three basic stages:
1. Collecting light - The leaf uses pigments in the form of chlorophyll cells to capture the light energy.
2. Light dependent phase - The effect of light on the chlorophyll cell causes a flow of electrons which splits the water into hydrogen ions and oxygen.
3. Production of sugars - The hydrogen ions are used in the reduction of carbon dioxide to produce sugars (glucose)
Transpiration.
This is evaporation of water from the plant. This evaporation happens through tiny pores on the leaf surface called stomata and helps create a pressure gradient to draw new water up from the roots into the xylem, where nutrients (minerals) can be carried up the plant in the transpiration stream until they get to where they are needed. Here, they can diffuse or be transported into the cells where they are required. Evaporation (transpiration) helps keep the movement of water going up the plant, creating our main transport system, the transpiration stream.
Nutrient uptake and transport.
All plants need certain minerals which we call nutrients . We put them in a bottle and when mixed with water we have a nutrient solution which can be used to feed our plants. The nutrient solution can be absorbed through the leaves as a foliar spray but is more commonly applied to the roots and absorbed through the root hair cells through diffusion, osmosis and through proteins that span the root membrane.
Once into the plant via the root hairs, the water and nutrient molecules will move through and around root cells until the nutrients enter the xylem where the transpiration stream will transport them to where they are needed.
The nutrients and water are used at their destination to make more complex molecules and help perform normal metabolic functions. Water again reaches the leaves where it transpires from the plant and also goes to play it's part in photosynthesis, and the whole process starts all over again.
Practical Applications.
Balancing conditions means having no weak links in the growing equation. This is the process of ensuring that everything is at good or optimum levels as far as light, CO2, temperature, humidity, oxygen and nutrient levels are concerned. Otherwise the plant will struggle to perform its various functions in an efficient manner and both growth and yield may suffer.
Air quality.
When growing light loving plants under lots of light, optimum respiration and transpiration occur with air temperatures about 25 degrees centigrade.
Water and nutrients.
The optimum water and nutrient solution temperature is 21 degrees centigrade. This will provide optimum oxygen content in the solution. Any warmer will reduce oxygen content in the solution and therefore in the plant. Nutrient Heaters, air pumps, and airstones, are a good idea.
Good air exchange.
In order to keep good CO2 levels and control air temperature you will need some natural ventilation or forced air exchange. Ideally, you should be completely replacing the air in your growroom 20 times per hour.
Oscillating fans.
These are very useful, but be careful not to blow too hard on the leaves where there is a lot of light or you will make the leaf transpire (evaporate water) too quickly. This will upset the natural transpiration and respiration rates of the plant and may cause leaf damage.
Good quality complete nutrient package.
When growing in hydroponics it's important to use a complete nutrient package, in other words a good hydroponic feed.
Nipping out.
This is only normally done on seed plants which tend to go straight up and are less bushy than cuttings. The effect of nipping the top shoot out would be to divert hormones and energy into the surrounding side branches and tips, which become stronger and bigger than they would otherwise have been, helping to have a bushier plant with more top shoots. In practical applications, this action can be performed to create multiple flowering sites.
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