Science of the Cannabis Plant Guide Summary: Successful cultivation requires plenty of knowledge, patience and practice. Here at Greenmans Page, we offer support and advice for growers of all experience levels. This article talks about the science of the cannabis plant.
Everybody knows that a marijuana plant needs water in order to survive. Without it, it goes weak, dries out and dies. It is also well known that the plant sucks up water through the roots, along with the nutrients. It all seems simple and logical, but in fact this is a complex process. If we take a closer look, we will find that all climate-related factors, such as light, light-duration, humidity and temperature are closely related to the watering process.
A marijuana plant consists of three parts: Marijuana Root, Marijuana Stem and Marijuana Leaf
Summarised, the transport inside the plant works as follows: The roots absorb the water from the soil. Then, the water and it’s nutrients are converted into new parts of plant. These are mostly large, organic molecules, which are used all around the plant (for example, as a growth substance in the roots). The engine boosting the production inside the leaves, is photosynthesis.
Water and solved nutrients continually have to go up, and the newly produced molecules have to go down. So we are not just dealing with the transport of water and nutrients, but also with that of ‘large’ organic matter. How this functions and why there are no traffic-jams, we will discuss that later. Let’s start with the roots. Water transport inside the roots A root has different functions. Aside from taking in the water, they provide stability of the plant. In balance with it’s top-soil counterpart, a root has to grow (ad synthesise new root-parts), and carry partial responsibility for the storage of reserve-nutrients. They are also the production facility for very specific molecules (like nicotine for the tobacco-plant)
Roots give the plant stability The roots hold a plant down in the ground, or other substance. They have the specific structure needed for this job. Both the guiding and the supportive plants of root form the axial strain. This helps the plant achieve great flexibility, as well as a good cable-structure. It also enlarges the available root surface.
The principle structure of a root is very visible with a seedling The central branch of a root-structure is the primary-root, which drills itself into the ground right after germinating. When the primary root has taken a strong hold and water supplies have been secured, the first leaves may be directed towards the light to achieve photosynthesis.
Then side-roots sprout from the primary marijuana root, increasing it’s surface and stability. All roots grow in one direction, enabling the out-growing hair-roots to anchor into the soil.
Marijuana Root-growth, and the short-life span of the hair vessels A root mostly grows at it’s tip. Close up to the newly formed cells is the root-unit, which controls the new-cell build up: a regular little root-factory. This production unit (meristern), moves forward along with it’s growth. Behind these tips, the newly formed cells are stretched out (cell-stretching). This part is followed by the hair-region, which is only a small part of the whole root. Still, the latter is the only part where water and nutrients are taken in. Because roots continuously grow at the tip, the root-hair region shifts along with it. In effect, this means the hairs have to be built up and broken down every few days.
Water transport inside the marijuana roots The hair-vessels are of a delicate structure, and are surrounded by thin shells, through which water and unsolved nutrients may easily pass. The resistance to water here is minimal. The outer surface is increased enormously by branching out. In the middle of the root we find the central cylinder: the highway up. Water flows here from the hair-vessels. This section has the largest resistance to water, for many membranes have to be passed through here. In the hair-root region, the plant has an enormous force outer surface, which has intensive contract with it’s environment. Clearly visible here, is the narrow contact between hair-vessels and soil-particles. Absorbing water does not come from active transport, but could well be compared to the cotton of an oil-lamp continuously sucking up oil towards the place of combustion (towards the flame). The intake of water by the roots is controlled through it’s suction. This has to be lower than that of the soil (otherwise water would flow from the roots into the soil). With extremely dry soil this may actually happen!). this water-suction is dependant on the amount of resistance water encounters in penetrating the root. The resistance is among other factors, influenced by the soil-temperature. This on account of the fact that water’s viscosity (it’s toughness) rises when the temperature drops (the water becomes thick). If the bottom is warm, this means low water resistance, but if it is cold, resistance becomes high. The second, and largest driving force behind water absorption is perspiration (the evaporation of water from the leaves). When much is evaporated, the suction in the roots grows larger (like with a fungus). Evaporating water from the leaves is in tune with the air-humidity (low R.H. = much evaporation, and vice versa) inside the room.
The following drawing depicts an experiment which proves that perspiration of the leaves causes suction (negative water-pressure) even greater than the force of regular air-pressure.
Demonstration of the suction which can only be achieved through leaf-perspiration. The plant may pull the mercury up higher as would air-pressure inside a barometer. This experiment proves that perspiration is the driving engine behind water absorption into the roots. Plants can experience water stress If ground temperature and air-humidity are both low, much water leaves the leaves through perspiration, but the roots can’t keep up, due to high water resistance. Symptoms: weak or dead leaves on wet soil, and decaying roots, of fungi will soon follow. Before we continue with more facts, let’s put this in practice. The plant-medium can’t be constantly dry or wet. Plants cannot actively absorb water, and never more than the amount which is perspired by the leaves. Don’t water ‘for storage’. This activity should be taken care of by your soil (perhaps by adding perlite). This achieves a water-buffer capacity. Hydro-systems should drop little but often, this imitating the water-buffer (not too wet and not too dry). The plant-medium should posses sufficient solidity in order to anchor the supportive roots, but it should also be soft enough to let the root-tubes through.
The microbiologic balance in the root-zone The microbiologic balance is a simple way of describing this very complex society of micro-organisms. These micro organisms have a big influence to the growing and blooming of the plant. It is very important for the serious grower to understand the balance in the plant and, if possible, to control it. A healthy microbiologic life always leads to an optimal macro-biologic life (grow and bloom). This is also known in the regular and professional gardening. This year many researches about the biologic balance started. Many research-institutes in Holland are investing millions of guilders in these researches. The Highlife grow-school gathered the most important facts and definitions for again an informative grow-school for the serious grower. The root-medium is a very complex thing, which is influenced constantly by the grower and factors of the outside. The grower influences by giving water, manuring of the plant, the choice of the substrate, the influence of temperature and light, the height of the pH etc. The most important outside factor is the separation out of the roots, also called root-exudates. Micro-organisms can be good or bad (they then cause diseases). When there are more good than bad micro-organisms in a plant and this situations is stable, then we are talking about a positive balance.
There are a few facts, which can influence a balance: Tap-water Tap water also contents micro-organisms. Every time you make water for the plants there are also micro-organisms in it. This influences the biological balance. Substrate The most occurred substrates are inert (it means that these don’t react with nutrition and roots), examples of these are rock-wool, PU-foam, oasis and Mapito (a mix of rock-wool and PU-foam). There are also organic substrates like coco and earth-mixes. The inert substrates do not influence micro-life very much. These are often that sterile that these hardly contain microbiologic life. This can be changed with biological means. Organic substrates on the contrary do have a lot of microbiologic life. Most of the times it is a positive balance, the quality-mixes for sure.
Root-temperature The presence of a micro-organism and the quantity of it, depends on the temperature in the root-zone. Every micro-organism has its own optimum. EC (solved salt-concentration) The complete salt-concentration is important for the fact that the micro-organisms can survive. The separate nutrition-elements can influence the growth of certain micro-organisms. Light Roots don’t like light at all. Micro-organisms that live in the root-zone also don’t like light. Organic substrates have a natural dark colour, so the root-zone is also dark. Inert substrates are often packed in plastic material, which does not let through the light. pH Fluctuations of pH influence the composition of micro-organisms. The more stable the value of the pH (5.5 – 5,8), the more stabled the microbiologic balance will be. Bio-means Biologic, bio mineral, organic means and means on the base of plant-extracts all influence micro-organisms. The newest means in gardening are bio-stimulators. The bio-stimulator influence directly the micro-flora. So can the bio-stimulators directly restrain influences of the disease-producing micro-organisms, so the good organisms can develop better. Chemical insecticides These synthetic means kill more than only mite or white fly. If the residue of the insecticides drips from the leaves into the root-zone, they also kill the positive micro-life. Also these means are not recommended because of the damage they can do to your health. Oxygen The type of substrate, how thick the layer of the system is and how often the plants get nutrition influence the amount of oxygen in the root-zone. If there is a lot of oxygen, other micro-organisms will develop then when there is a lack of oxygen. Root-exudates Besides the enumerated factors which can influence the grower, there are processes in the root-zone, which are influenced by the plant itself. These are the so-called root-exudates. These separation-products can consist sugars, amino acids, phenols, phenol-acids or other organic combinations. Sugars and amino acids can serve as nutrition for the plant, so they can play a grow-stimulating role. Phenol-combinations and certain organic acids can restrain the growth of the plant if the strength is too high. Also bio-stimulators can be a part of it. Bio-stimulators can break down all kind of organic combination so the plant can absorb it. That is why I advise the serious grower to check the micro-climate of his plants… it can make a lot of difference…
Summertime vermintime The summertime not only gives us pleasant warmth, but also for the ones with six or eight feet that love the green growth. Especially the greenhouse red spider mite loves a warm and dry climate and if you see the little ones walking, the harm already has been done. The red spider mite not only tap the fluids from the plant with every bite, there also stays a mark on the leafs. That’s why the plant cannot perform photosynthesis. Also the tissue of the spider-bite close the plant more and more from the air. The plant is weakened by many sides and is getting weaker by the hour. This is the moment that the grower has to go to the grow-shop (or to another place where you can buy vermin fighters) and get some help. If the whole harvest is threatens to die, a very strong matter is often used. But when this matter is harmless, irritating be very dangerous for your health and the precautions necessarily taken, is often left out of consideration. Most pesticides are made for use in free nature or in greenhouses, which, comparing with most of the growing-places, are much bigger. If pesticides have to be used in a greenhouse, it is obliged by law to protect the co-worker for 100% against all kind of influences of the chemicals. This can mean: gloves, special suits and a mask for breathing After the treatment the greenhouses are ventilated and a certain time has to pass before any work can be done. In home growing it often is a different story. The space is often low-pitched and is full of plants, what diminishes the moving-space of the grower. Natural ventilation lacks most of the times, because the light and smell would come outside, unfiltered. Working with gloves in this heath is a torment and a mask for breathing or protection-glasses let run down the sweat in big floods. Working with pesticides in small oppressive rooms is causing a lot more danger than in big greenhouses or at the outside. Measures at mixing ready-to-use solutions A pesticide is often offered in highly concentrated packages and has to be mixed with water before use. Contact with skin and eyes have to be absolutely avoided, because these concentrates can be very irritating or biting and can go through the skin also in concentrated form. Working with gloves and/or glasses is highly recommendable. You have to work on an easy height (table) and not on the ground. Do not work under hot lamps, because the concentrate can go directly to your lungs. It can also be dangerous if parts of the pesticides are mingled with fertilizers or a base. So do not measure your nutrition in the same tray. If you buy a matter that’s already has useful dosage, you have no trouble with this. Measures while squirting During the squirting there is a big chance to inhale the pesticides. It can also go through your skin. If you use irritating or poisoned matters it is necessary to work with masks for breathing. The evaporations of the pesticide are getting stronger by the heath of the lamps (especially in small, low-pitched rooms). Very important for the use of every squirting-matter (if it is dangerous or not), is that every part of the plant that is infected (also the underside of the leafs) are hit. That means you have to do this quiet and careful. So take care that you not have to cough or that your eyes are burning, when you are only halfway. That is very bad for your harvest, because you don’t fight the vermin well. Clothes and hairs are after the squirting of the vermin also soaked with the used matter and you can at best put the clothes immediately in the washing machine or use them next time. This is of course particularly important if the growing room is in the living room. A safe use of poisoned or irritating squirt-matters is difficult to realize. It asks for an air-tight shut-off part of the house (some means can easily damp through walls – look at the bottom at groups of matters). The ventilation has to be put on maximum, after the necessary initial period, to remove the remainder. Growing-lamps have a part of the UV-light in the spectrum. UV-light breaks off biological and chemical substances and according to the representative of the Minister of Agriculture the lamps can produce very dangerous substances by beaming. It is hardly investigated how the waiting period of for instance matters for the growing of vegetables and fruit changes, if it handles about growing weed (the sticky outside can absorb and hold lot more substances than a cucumber). And if the waiting period for the vegetables are sufficient, it you don’t eat it but smoke it. Never ever mingle concentrated pesticides because all kind of reactions can take place and you can not predict it (so do not make a mix). A categorization A pesticide which is permitted in Holland, has always, in the original package, information about the contents, way of use, warnings and waiting periods. The relevant pesticides mainly work in two ways. The pesticides can be divided in: Organic fatty acids do their work in contact and weaken the parasites. They are quite harmless for people. Natural and synthetic pyrethroid like permethrin work as a nerve-poison against insects like plant louse. Phosphorus-acid ester dichlorvos, parathion (E605) malation work as a breath-poison* Tinorgan connections (acaricide = anti red spider mite, many of those are very poisonous) Others are: carbamate, acylharn-substances, amidine, dinitrofenol, thiocyanate. * Phosphorus-acid ester (and also the carbamate) block an enzyme that controls the nerve-impulse. When admitted a permanent stimulation of the nerves is caused. This will kill the insects and the red spider mites, but can, used careless, provide the human being sickness, diarrhea, spasms, lower the blood pressure and paralyze the breath (the nerve-gasses tabun and sarin also belong to the Phosphorus-acid esters). Some of these are very volatile chemicals and are potentially dangerous for the plants themselves, because they can burn. To prevent this, you have to wet the ground very well, before treatment, because otherwise the roots, and therefor the plant, is getting damaged. Also the squirting in the evening is good, because it causes during the night (when the light is out) less evaporation and demolition. When applied wrong or when used regularly, most matters will not work any more, because the insects and mites get used to it (get resistant). Use of pesticides is very difficult and can give many problems. The most harmless method of fighting insects for the grower and the consumer is the use of natural enemies like mite and gallflies etc. Simple tricks, like disinfecting the nursery after every harvest, keep the cuttings before the planting in quarantine for a few days or plunge or disinfect them, can prevent an epidemic in the blooming-phase. By improve the climate in the nursery, most infections with insects can be prevented. Nurseries that get infected over and over again by red spider mite, have a too dry climate. By squirting the plants with water regularly, (once a day) the mites are less mobile for 50% and it is very satisfying to watch the little creatures having trouble on their highways (the spin ropes) to climb over the droplets over and over again. By keeping the conditions of growing (temperature, air-humidity, suction and adding of air) optimal, the natural resistance of the plants are getting higher. Spoil the plants with root and bloom supplements, which by adding of many vital maters (enzymes, vitamins, sugars and amino acids) bring extra energy for the plants.