From Dutch Master Nutrients 1/24/2018
Silicon is perhaps more misunderstood and under appreciated than any other element. Widely viewed originally as an element not essential for plant life, now silicon is scientifically known to provide countless benefits to plants, benefits that cannot and should not be denied.
The primary issue with attempting to classify silicon’s essentiality to plant life stems from silicon’s abundance on our planet. It seems that silicon can be found just about anywhere (and rightfully so, given that roughly 28% of Earth is comprised of silicon). What we do know, as a result of numerous silicon-additive studies, is that plants fare much better throughout all growth cycles with the addition of silicon through increased yields, growth and protection against toxic heavy metals, cold and heat stress, pests and pathogens (fungi and mold)
By mass, silicon is the eighth most common element in the universe and is also the second most abundant element on Earth. It is interesting to note that nearly 90% of the Earth’s crust is composed of silicate minerals (containing oxygen, silicon, and various reactive metals - Mica and Feldspar are great examples). These complex silicate minerals are the most commonly encountered form of silicon. Very rarely are pure, elemental silicon crystals ever found in nature.
It was initially believed that silicon was transported along with water, but recent research has indicated otherwise. What we now know is that silicon is actively absorbed through various transport proteins, as shown by the recent discovery of silicon transport genes in rice species (Ma et al. (2006)). The specific transporters are Lsi1 and Lsi2 (Lsi = Low-silicon) and are located on the distal and proximal sides of the endo and exo dermises of root cells, respectively. From here, movement continues upwards as an inorganic solute into the xylem, much like other elements (e.g. potassium).
Silicon provides many benefits for plants including increased shoot and root density and increased yields (of which up to 65ppm of Si has been shown to be the most advantageous in hydroponic systems)
, it more importantly provides a much needed defense for plants against both biotic and abiotic stressors. Silicon is unique in that it provides both physical and biochemical protection. It is widely known that silicon is deposited in the cell wall of many plants, however, research has shown that silicon deposits are also found in trichomes. These deposits act quite literally as a physical barrier, preventing attacks from pathogens and herbivores. Given that trichomes are the primary site of secondary metabolite production, bolstering trichomes results in a more efficacious use of a plant’s endogenous secondary metabolites for pathogenic protection and an overall increase in trichome quality and health.
Silica has also been shown to be an inducer of SAR (systemic acquired resistance) - stimulating natural plant defense responses. These defense responses are effective against many diseases and insect attacks, including powdery mildew prevention, fungal disease protection, and biting insect suppression (mites, whiteflies, etc.) for which it is registered with the EPA for use.
Perhaps the most intriguing facet of silicon as of late is research indicating that silicon plays a significant role in promoting the biosynthesis of various defense compounds.
While the exact mechanism is still unclear, it is speculated that silicon forms a ligand of an organic metabolite that results in the promotion of defense genes within the plant. What we do know is that in conditions where plants are facing various stressors, the up-regulation of defense mechanism genes is heavily influenced by the presence of silicon.
From Maximum Yield 3/1/2017
Silicon strengthens cell walls and stems, creating a plant that can bear the weight of large fruit.
A larger stem also means that a plant can uptake more nutrients and water at once, allowing the plant to grow larger faster. When fed to cuttings and seedlings, silica supplementation has been known to lessen the shock of transplanting and strengthen the stems at a faster rate.
Silica also aids a plant’s ability to withstand stress from temperature and drought.The strong cell walls are better able to expand and contract during extreme temperature changes so that the stress has less of an impact. This is especially helpful outdoors in the cooler seasons, when temperatures can drop drastically at night. It also helps a plant hold onto more water during transpiration, which is good during the hot, dry days of summer.
Pests and disease will have a harder time attacking your plants when silicon levels are up, too.Silicon builds up in plant tissues and bind together to make it harder for pests to eat through the tissue.All this hard work takes more of the pests’ energy and slows down their reproductive rates.
Silicon has also been shown to ward off fungal diseases such as powdery mildew, rust, and pythium. Some studies have also shown that silicon specifically builds up in areas of infection on plant tissue to protect the plant from further disease. Foliar feeding with silicon is an effective preventative practice, especially if your environment is the hot and humid conditions in which fungal diseases would thrive.
Many studies have been conducted on the effects of silicon in plants. A 1986 study on how the micronutrient affects cucumbers found many positive benefits. Most notable were the resistance to powdery mildew, more chlorophyll content in the leaves, increased root weight, and delayed senescence.In other words: the plants had more roots and greener, lusher foliage,leading to more fruits.
A 2014 study found that silicon protects plants against metal toxicity by decreasing metal availability in the plant and affecting metal distribution inside the plant. The same study also found that silicon mitigates the symptoms of iron deficiency in plants.
Research at the University of California, Davis, has studied the effect of silicon in dwarf citrus, chrysanthemums, and roses. Their results showed smaller pest populations on the citrus and chrysanthemums. Similar research discovered that there was a decrease in leaf miner populations on citrus and chrysanthemums when potassium silicate was added to their water.
Some plants benefit from this element more than others. For example, rice and sugar cane accumulate large amounts of silicon, whereas cucumbers accumulate a moderate amount and tomatoes accumulate very little. For silicon accumulators, it is absolutely beneficial to add silicon to your nutrient solution, especially if you’re growing hydroponically.
Considering Cannabis is a Hyper Accumulator (A hyperaccumulator is a plant capable of growing in soils with very high concentrations of metals, absorbing these metals through their roots, and concentrating extremely high levels of metals in their tissues), and that Silicon "protects plants against metal toxicity by decreasing metal availability in the plant and affecting metal distribution inside the plant."
I wouldn't recommend growing without it, Id compare Silicon to coffee/caffeine, its not necessary but it sure seems to help.