A lot of time and money has been devoted over the last decade into researching the cold plasma treatment process. Here’s how it works.
Imagine a viable seed-treatment process that would allow seeds to germinate faster than their non-treated counterparts, and help plants grow quicker and produce more fruit, all while remaining compatible with organic gardening guidelines. Such a treatment, which requires no chemical inputs or genetic manipulation, does exist, and researchers and private enterprises are currently experimenting with this method around the globe. It is not a new method—published research on it goes back as far as the 1970s—but researchers and scientists have devoted enormous resources over the last decade to determining the benefits of treating seeds with this method.
The cold plasma treatment process adds air to the coating on seeds by creating tiny holes so the seeds are able to absorb more water during germination. If it has been a while since your last physics class, let me provide a layman’s definition of plasma. Plasma, the fourth state of matter, is one energy step above gas. The other two energy states are solid and liquid. Any matter in its gaseous stage can become plasma if it is ionized, or given enough energy to cross the barrier between the gas stage and the plasma one.
Plasma is all around us. The sun is composed of plasma, and so is lightning. Fire is a plasma, as are the flickers of the fluorescent lights so many of us see on a daily basis. Any gas that is hot enough to be seen can be considered a plasma. But plasma is not always hot bundles of energy. Plasma-treating seeds involves the use of cold plasma at an extremely low atmospheric pressure, as hot plasma would cook the seeds (popcorn, anyone?) Temperature and pressure are directly proportional, so to lower the temperature to perform the cold plasma treatment, the pressure must be reduced.
How Cold Plasma Treating Seeds Works
The air we breathe is primarily comprised of nitrogen and oxygen (about 78% and 21%, respectively). Another plus or minus 1% percent is argon, 1% water vapor and .04% carbon dioxide (this adds up to just over 100% because these percentages are approximate). Nitrogen and oxygen both have two atoms per molecule, so they exist diatomically.
Plasma treatment of seeds occurs in a vacuum chamber, where super-charged air is introduced to plasma. For this process to occur, the air inside the chamber is exposed to a radio frequency at 13.56 MHz to break the nitrogen and oxygen molecules in half, creating free radicals. These free radicals are highly reactive and very unstable. They seek out any available surface with which they can bond to. Enter the seed. Seeds, which are primarily composed of carbon, are an easy surface for the nitrogen and oxygen free radicals to adhere to.
The increased amount of oxygen on the seed coat increases its electric charge and makes it more polar. Water is a polar molecule, and since like dissolves like, the seed is able to soak up more moisture during the germination period. This increase in water absorption boosts the metabolism rate of the endosperm, which translates to a faster breakdown and use of the nutrients contained within the seed, allowing the plant to develop and grow more quickly. Plasma-treated seeds produce seedlings with more mass, length and vitality. Treated seedlings also tend to possess greater axil leaf bud development.
The Potential of Plasma Treated Seeds
How does faster germination help? Ecologically speaking, treated seeds would be able to out-compete weeds. As anyone who has a home garden can attest to, one of the biggest annoyances is the constant pulling of weeds. Weeds rob our crops of solar energy, water and nutrients from the soil. If our crops germinated faster in the soil and got a jump start over the weeds, they would be the clear victors. Faster germination times could translate into many benefits for farmers and home growers alike from a harvesting standpoint. Crops could be ready sooner and on our tables earlier. This could allow for more successional plantings and more harvests per year.
A 2005 study on plasma-treated tomato seeds found the treated tomatoes had a 28% higher germination rate, an 8% higher total survivability rate and an 11% higher number of plants surviving to the transplant stage than the non-treated control seeds. The treated plants continued to outperform the control plants as development continued—yields were 22-26% higher for the treated seeds and the weights per tomato were 9-16% higher in the treated versus non-treated plants (Meiqiang et al., 2005).
Research has repeatedly shown a correlation between plants receiving a cold plasma treatment during their seed phase and increased yields per plant, including increased mass of total yield per plant, mass per fruit, size of fruit and quality of fruit.
Besides the obvious potential benefits of better germination, growth and yield, the increased water absorption of plasma-treated seeds could mean less irrigation water is needed. This has obvious benefits to all, but especially to farmers and growers living in arid parts of the world, or even those living in the suburbs facing water restrictions during the summer. This increased hydrophilicity can also increase the storage time of seeds, allowing for a greater amount of time between the treatment and the sowing of the seeds. Farmers and gardeners need only plant as much as they need, confident that the germination rates for the following season would still be acceptable.
Another huge benefit of the cold plasma treatment is the seeds’ ability to resist disease. Seeds treated with plasma have anti-microbial and anti-fungal properties. The cold plasma treatment essentially inactivates any bacteria and fungi present on the seeds. This means fewer seeds are lost to common diseases such as damping off, and conventional seed treatments, from hot water to chlorine and fungicides, can be reduced or eliminated altogether.
The potential for this technology is amazing, as it could help preserve rare and disappearing plant species. A 2009 study looking at the effects of cold plasma treatment on the dormancy of seeds revealed that along with the increased germination of seeds, dormancy levels were reduced. Species with naturally long and extended periods of dormancy, which are disappearing due to plant competition by invasive species, could get a reprieve. Treated seeds could be re-introduced to allow these endangered plant species a better chance to survive (Será et al., 2009).
Plasma treatment is also a promising step forward in the fight against genetically modified seeds, as it could potentially provide the same benefits that GMO seeds do. Research is ongoing—not all types of seeds have been treated, with results well-documented. As a consumer, you can ask for seeds from your local nurseries and garden centers that have been treated using the cold plasma method.
You may have to educate the people you ask, but it will help raise awareness and get these seeds into our collective hands sooner. There are still many years of research and millions of dollars to be spent on getting these seeds into the marketplace on a grand scale, but our salvation from GMO seeds may be right around the corner.