Plant philosophy
Silicon for plants – what is it and how to use it?
<span class="bsf-rt-reading-time"><span class="bsf-rt-display-label" prefix="Reading Time:"></span> <span class="bsf-rt-display-time" reading_time="6"></span> <span class="bsf-rt-display-postfix" postfix="min"></span></span><!-- .bsf-rt-reading-time -->

Silicon for plants – what is it and how to use it?

I find silicon a hot topic not only in the realm of aesthetic medicine ;). I see more and more interest in micronutrient supplementation for plants. As I am a huge supporter of the highest prevention of possible plant problems, I’ve decided to start with the the silicon function and its demand in plant tissues.

In nature, silicon appears mostly as silicon dioxide, commonly known as…sand. This form is, as you can imagine, not a friendly one for plants to assimilate. After reading this article you will know wether your plants need this kind of support and why. Then we will move to practice. How to choose suitable silicon suplement for you plants, where to find it and how to use it.

What is silicon

function in plant tissues

Silicon is an element commonly found in the earth’s crust. Depending on the type of soil, it constitutes from 5 to 40% of its composition. However, the pool of silicon that plants can actually use is very small. Everything depends on the form in which silicon is bound.

The chemical compound carrying silicon must be able to ultimately give away the cation (Si4+) into solution, and the plant must be able to take this cation through the appropriate channels in the roots (or the epidermis of other parts if we are using foliar spray) and build them into its tissues.

It sounds like a simple road. But first, the silicon molecule is relatively “heavy” when we compare it to other elements. There are elements that can cross the cell wall barrier more easily. This is for eg. sodium or potassium. Nonetheless they still require the presence of specialized transporters on the epidermal surface of the root). An additional problem is that silicon does not form water-soluble salts, so it has to be bound to the acid radical in nutritional formulas. Enough of the chemistry, I promise.

Note that the walls of higher plants have highly specialized structures that do not let just anyone inside ;). The introduction of silicon may therefore turn out to be quite a break-a-neck undertaking. But there are ways! And the crucial way in this case goes trough the appropriate pH.

So, we know that we are looking for the compounds that will give the silicon away easily. But what is its function and why even bother to give it to the plants anyway? What to expect?

How is silicon used in the plant metabolism is a first question. The second, is giving it separately making any difference to the plant? I mean…normally it is not like plants have a vast silicon deficiencies as it is really a micronutrient.

Who needs silicon?

and why…

I look at this this way: it is a bit like taking supplements for hair growth and overall “health and shine” actually almost exactly like this ;)). Some of them make the condition of your hair better and your skin to glow and well, for the plants this also translates into many benefits.

Who needs silicon? Well everybody I guess..

Silicon plays an important role in plant life, mainly consisting in creating defense mechanisms against unfavorable environmental factors. It creates a mechanical barrier not only in cell walls but also in intercellular spaces and inside of cells (think of it as sealing!).

It benefits the metabolism of the plant by increasing the concentration of chlorophyll. Not only it enhances chlorophyll and other assimilation pigments synthesis but also intensifies the process of sugar synthesis which leads straight to the green mass increase.

Plants, that consume larger amounts of silicon are characterised by a more economical water management and a lower transpiration coefficient. As water evaporation losses are reduced, they also have a lower water requirement.

The use of silicon minimizes the effects of soil salinity and as to the hydroponic cultivation – also helps to flush saline from the hydro substrate.

Lets take a closer look as to the Aroid and Hoya cultivation. Are these the families that would use some silicon in a good way ;)?

Both Hoyas and Aroids, despite the fact that they grow in lands with a different composition, they are climbers (mostly). That means, that they search for the necessary nutrients somewhere else than the soil. In the rain forest it is mostly what drips from the canopy and therefore, what is soluble in the water (and other plant and animal debris). If they assimilate silicon, I think it will be mostly throughout the the foliar route (which is the most efficient way according to the research).

So, if they can use this compound for their benefit, then it would be preferable to make sure that it is soluble in water and preferably administered via foliage or in hydroponic cultivation.

What to expect?

outcome of silicon supplementation

So, the silicon suplementation is a form of growth stimulation and we should expect…results!

As silicon will be mostly build into the cell walls (strengthening them), what we expect from this is a bigger mass of the green parts, roots and a bigger fruit mass. Why?

Alert – this is my personal brainstorm: if the epidermis is thicker and more compact, then it is less prone to micro-damage, less pollution gets inside, fewer pests are able to “chew” inside and the plant is able to bear its (higher) weight. Sounds about right.

Now let’s have a closer look for those, who are interested in a bit more specific mechanisms. Ok, we have indirect and direct effects of silicon supplementation, and they are as follows:

Silicon influences the plant indirectly by creating better conditions for its development. It improves the availability of nutrients in the soil and collaborates in their mobility in plants. It concerns for example potassium and phosphorus.

In a direct participation, silicon saturates the conductive beams in the plant, thus preventing their sagging, and thus facilitating the transport of water in the plant. In other areas, it influences the polymerisation of the cytoplasm (meaning influences its consistency as silica is able to bind water). How does it work? Due to the capability of amino acids to form compounds with silicon (which “likes” water), it hydrates the compounds and causes gelation.

Silicon has also antioxidant properties that reduce the amount of reactive oxygen particles produced. So it decreases so called “abiotic stress” (means physical), which occurs primarily as the appearance of harmful reactive oxygen particles. Less stress means of course healthier plant.

Additionally, silicon reduces the level of lipid oxidation in the cell membrane and reduces uncontrolled permeability. After entering tissue structures, silicon replaces lignin in cell walls. This facilitates cell expansion and plant growth (as everything is more “tight” ;)).

Silicon leads to a greater uptake of potassium and calcium, and – as you know – potassium is responsible for the proper water management.

And the last thing, but very important indeed: we can prevent pests to attack our plants by using silicon boosters. How?

In some research (yes, I’ not specific, but I forgot the source) scientist noted an increased uptake of silicon in plants that were subjected to cyclic damage. This was done both after stimulation in the form of leaf trimming and after being “chewed” by pests or small animals. Then the absorbed silicon accumulated directly under the epidermis. The silicon-rich leaves lead to increased, irreversible damage of the insect mouthparts during the feeding (yay!).

Where can we find silicon and how to use it?

My analysis

As we cannot provide the perfect conditions for Aroids and Hoyas in our home environment (even with the tents and cabinets), in my opinion it is worth to use silicon from time to time as a growth an immunity booster.

The re is one problem though. Orthosilicic acid, when released into the soil solution, becomes unstable. Its molecules show a high polymerization tendency and easily transforms into insoluble and inaccessible forms for plants. Therefore, the absorbable amount of silicon for plants in soils is relatively low. Paradoxically, plants growing in soil containing very large amounts of silica may experience its deficiency.

The best way to meet the needs of plants for this element is foliar feeding. It is also efficient when feeding the plant in a hydroponic cultivation.

I know at least two supplements with silicon:

RHINO SKIN form Advanced Nutrients contains of Potassium silicate (K2SiO3), which is widely used in horticulture.

USAGE: 2ml/L

TOP MASS from Top crop – contains hydrated silicon in a form of non-colloidal Orthosilic acid.

USAGE: 0.1-0.2ml/L

The bioavability of this compounds according to both producents is of course unbelievable. The best way to really find out, in my humble opinion, is to try and compare the results. From the theoretical point of view both compounds are bioavailable, but silicon is still a hard partner to work with. Also: potassium is always a good addition when it comes to the composition of plant supplements.

ALERT! The most important thing with using silicon in both hydroponic and non hydroponic cultivation is that we do not add ANYTHING else when providing plant with silicon. Why? The pH of this solution should not change if you want it to stay bioavailable.

If we adjust the pH as normally to 5.6, then the silicon might turn into…a gel :D. Then it will not be you know…”digestible” for plants. In the hydro cultivation, after the plants will absorb the silicon, we can proceed with rinsing and adding a normal fertiliser.

As usual, let me know if this was useful and not too geeky!

Leave a Reply

Your email address will not be published.